Not only are tomatoes the most widely consumed vegetable in the world, they are the “quintessential” crop for backyard gardeners.
However, many pests find tomato fruits and plants as delectable as we do. Many different pests attack tomato plants from the time they first emerge from the soil to the time that your tomatoes are ready for harvest.
As if that were not bad enough, many pests can also introduce damaging diseases to your tomato plants.
Some pests practically trumpet their arrival, such as tomato hornworms, which produce enormous caterpillars. Other pests, such as spider mites, have more subtle symptoms and can be harder to diagnose.
Knowledge is power, and keeping a close eye on your plants will let you know sooner than later when they are under siege. Be sure to look under the leaves when you inspect your tomato plants!
You may also want to keep a magnifying glass handy to check for mites and thrips.
Don’t worry. Not all these pests are found all over the country, and your plants are likely to be faced with a subset of them.
Our goal is to provide the information for you to readily identify pests on your tomato plants and vanquish them before they do much damage. Let’s dive in!
Most gardeners are well aware of these small pests. They are tiny insects with soft bodies that form colonies and suck and feed on leaves and fruit.
You can usually find them on the bottom of leaves.
Aphids can grow up to 0.14 inches (3.5 mm) long. Several different types of aphids can infect tomatoes.
These two species that are frequent pests of tomato plants include the potato aphid (Macrosiphum euphorbiae), which can be pink or green, and the green peach aphid (Myzus persicae).
The green peach aphid is found in all parts of North America.
These insects cause a great deal of damage despite their small size. And they breed like rabbits (or worse). In Florida, the aphids are born pregnant! Some species reproduce as soon as 7-10 days after they were born.
This can rapidly create high populations of aphids, which can cause the leaves and stems of tomato plants to become distorted and the plants stunted. The infested leaves can be spotted with dead sections.
Another problem is due to the sweet substance the aphids excrete called honeydew. It accumulates on the leaves and can cause a fungal disease called sooty mold.
This disease hampers the ability of the leaves to photosynthesize and produce sugars, which can sap the host’s vitality.
Which aphid is worse?
The potato aphid is much larger than the green peach aphid and attacks the plants later in the season. These factors cause the potato aphid to be a more severe pest. The green peach aphid is primarily an early season pest.
Be sure to check your plants 6-8 weeks before you expect to harvest your tomatoes. A common way to dislodge aphids to spray them with a stream of water.
Prune the foliage
If you have excess foliage that is infested, be ruthless and prune it!
You can protect your young tomato plants by mulching your garden with aluminum- or silver-colored mulches. These repel the winged aphids and can delay damaging numbers of aphids building up by 4 to 6 weeks.
If there is a history of viral infections, you should place the mulches on the beds before planting seeds or transplanting young plants.
These mulches will only be effective early in the season. Once more than 60% of them are covered with foliage, they lose their effectiveness.
Aphids are vulnerable to an array of natural predators, including lacewing and ladybug larvae. Nature might be taking care of the infestation for you.
Look and see if there are dead, mummified aphids on the leaves. Compare their proportion to that of the active aphids.
If there is a high proportion of mummies, you should not spray the aphids to dislodge them because doing so would also dislodge the natural predators.
Keep your local source of ladybugs and lacewings on speed dial, and release large numbers of them to control the aphids.
Spray horticultural oil or soap
If the population of aphids seems out of control, it might be time to bring in chemicals to control these pests.
An oil, such as neem, is usually a very effective insecticide. Thyme oil is another option. Both are considered organic treatments.
However, these sprays will also kill the natural predators, so be sure that the aphid population is really out of control before you spray.
These are the caterpillars of two types of moths – Spodoptera praefica (western yellow-striped armyworm) – and S. praefica (beet armyworm).
Beet armyworm larvae can be the most important caterpillar to afflict tomato plants. As few as one caterpillar per 20 plants can cause economic damage in fields.
The beet armyworm originated in southeast Asia and was discovered in North America in 1876. It is sensitive to frost and is rarely a pest except for the southern states. (However, it can be a problem in greenhouses.)
Beet armyworms have an exceptionally large host range, which ranges from an array of vegetables to weeds.
Western yellow-striped armyworm
You can recognize the western yellow-striped armyworm caterpillars by their black color and the yellow stripes along their side – two prominent stripes and many fine lines.
These caterpillars are distinguished by a characteristic black spot above the second pair of legs behind the head.
The young larvae range from yellow to pale green, while the older larvae are usually darker green with a light line that runs along the side of their body. Their undersides are pink or yellow.
Western yellow-striped armyworms are not frequent pests of tomato plants and usually occur when they migrate from nearby alfalfa fields or beans or other crops after they have been harvested or dry out.
Therefore, they are less of a problem in home gardens.
However, beet armyworms are a widespread pest in tomato fields in the southeast and southwest. They are found in California tomato fields each year.
This pest has several generations per year.
Most of these nocturnal moths only live for a week, but each can lay up to 600 eggs during this week.
The females start to lay eggs two days after mating. They prefer to lay their eggs on young rather than old tomato plants.
The eggs are in masses of 15 to 150 and are mostly on the undersides of leaves. You can find them within four inches above the soil.
The caterpillars are cannibals and will eat each other. Interestingly, the moths that develop from cannibalistic larvae lay more eggs than those that have only fed on tomato plants.
The larvae pupate in the soil for about a week. However, they can overwinter as pupae in the soil.
Infestation during the early growing period of the tomato plants causes more damage.
These caterpillars chew circular or irregularly shaped holes in leaves. They can eat all the tissue between the veins, which makes the leaves look skeletonized.
They also feed on the fruit, although their feeding is often shallow. Such tomatoes can frequently be used to make paste, but they are too damaged to be offered for sale.
Sometimes, the caterpillars feed inside the fruit, which causes damage like that of tomato fruitworm.
An enormous number of natural predators help to keep these pests under control. They are vulnerable to several parasitoids, fungal diseases, and a devastating virus.
Red imported fire ants are important predators of the pupae in the soil.
You do have options if the natural predators are not controlling these caterpillars. You can treat the egg masses with petroleum oil.
Also, you can treat infested plants with the biological control bacteria Bacillus thuringiensis (BT) ssp. kurstaki (BTk). That is probably your best bet since many populations have developed resistance to insecticides.
If you still want to control these caterpillars with insecticides, you have several organically certified options. These include neem or the organic insecticide spinosad that is available as Bonide® Captain Jack’s Deadbug BrewTM.
The pupae in the soil are vulnerable to nematodes that are specific for insects.
3. Beet Leafhopper
These little insects are pale green, tan, or gray and are 0.12 inch (3 mm) long.
Transmission of a virus
These leafhoppers are not much of a threat to tomatoes in and of themselves, but they transmit a severe viral infection to tomatoes: beet curly top geminivirus.
Even if the leafhopper feeds for just minutes on a tomato plant, it can transmit the virus. To make things even worse, these leafhoppers remain infected for the rest of their lives.
This virus causes infected plants to stop growing and become yellow. The leaves turn purplish and roll upwards, and the stems and leaves become stiff.
Insecticides are not very effective at controlling these pests, which can live on a wide array of weeds. Other methods for controlling this pest include:
- Eliminating weeds – Eliminating weeds near your garden and volunteer plants from previous crops are the best ways to prevent infestation by these insects.
- Planting resistant varieties – ‘Columbian’, ‘Roza’, ‘Rowpac’, and ‘Salad Master’ have shown resistance to the beet leafhopper.
- Planting a higher density – This makes it less likely that every plant will be infected.
- Using floating row covers – These are fabric covers that you place over the areas where you will grow your plants.
4. Blister Beetles
These beetles include several species in the genus Epicauta and are an infrequent pest on tomato plants. And if they do infest, it is usually only for a week or two.
However, it is important that you be familiar with them because these beetles can cause severe skin blistering if you handle them. Avoid handling them at all costs!
The chemicals they make are also toxic if you inadvertently eat them. Interestingly, the primary chemical cantharidin is extracted from European blister beetles to make the aphrodisiac Spanish fly (which doesn’t work well).
The beetles are slender and up to ¾ inches long (19 mm). They have prominent heads that look bulbous compared with their thin necks. The bodies are usually black and sometimes have yellow stripes on the side.
Leaves consumed by them will look ragged.
Some experts recommend wearing gloves and knocking them into a bucket of soapy water. However, as Joe Boggs from the Ohio State University has commented, that can be a real challenge that “usually ends with a hasty retreat accompanied by a string of expletives.”
Your best bet to manage these beetles is to control weeds near your tomato plants. These beetles thrive on weeds that are closely related to tomato plants, which include horse nettle and black nightshade.
They can build up really high populations on these weeds and then migrate to their favorite hosts like tomato plants. Limiting weeds and keeping a close eye out for blister beetles should help you to minimize damage from them.
5. Cabbage Looper
You can recognize these caterpillars by the way they move. They crawl by arching their backs, which looks like they are forming loops.
The caterpillars are green with white stripes and grow to about one inch (30 mm) long.
Cabbage loopers infest a wide variety of plants. They eat large holes in the leaves, but they are generally not a severe problem.
Surprisingly, infestation on tomato plants can even be a good thing! They are an alternate host of the parasitic wasps that control the much more damaging tomato fruitworm and other types of caterpillars.
You only need to worry about treating an infestation if they are destroying so much of the leaves that the fruit might get sunburned.
The biocontrol bacteria Bacillus thuringiensis or spinosad will keep them under control.
6. Colorado Potato Beetles
Tomato plants are very closely related to potato plants, and the pests of one will frequently attack the other. That is the case for Colorado potato beetles.
Left unchecked, these beetles cause severe damage and can completely remove all the leaves on their hosts.
Fortunately, the beetles are very distinctive with their black and yellow stripes. They are about half an inch long (14 mm).
The beetles overwinter in the soil as adults and emerge in the spring. The females lay eggs on the bottom of leaves in batches of about 24. A single female can lay 500 or more eggs over the course of about a month.
When the larvae first hatch, they have bright red bodies and black heads. They turn pink as they grow older.
These insects have developed a high level of resistance to most insecticides, and the most effective way to control them in a backyard garden is to pick the adults and larvae off by hand and put them in a bucket of soapy water.
Bacillus thuringiensis can be effective at controlling the larvae, but you will need to apply it frequently. The insecticide spinosad is still effective against the adults.
This might sound a bit scary, but if you have many tomato plants with beetles on the top of your plants in the spring, you can quickly move the flame from a propane torch over them. The beetles tend to feed on the top of their hosts, and if you do this carefully, you will not damage your tomato plants.
- Black cutworm (Agrotis ipsilon)
- Variegated cutworm (Peridroma saucia)
- Granulate cutworm (Feltia subterranean)
Cutworms are one of the most important pests that afflict tomato plants and fruit. While there are many different types of cutworms, they all do the same type of damage: cut your plants down! Their damage is so severe that they have been said to “annihilate” a new crop.
Even just a few cutworms can severely damage a garden. To make things worse, these pests are common throughout the US and Canada.
They can feed on a wide range of plants, which increases the likelihood that you will encounter them in your garden. Their numbers vary. They can be a severe problem one year and then not the next.
These voracious 1-2”-inch long larvae are active in the late afternoon and night and cut through the stems of plants right above the soil surface, causing rapid and large-scale damage. They do the most damage on young plants since they have thinner stems.
Some cutworms can crawl up the plants to feed on the leaves, buds and shoots. Some species will eat the fruit, causing irregular holes on their surface. Tomatoes that touch the ground are usually injured the most seriously.
Cutworms overwinter as larvae or pupae in the soil. The surviving larvae emerge in the spring and then begin feeding on plants. This continues until they mature and form pupae in the soil.
The moths emerge 2-4 weeks later. They soon lay eggs on the bottom of the leaves at night, and a single female will lay hundreds of eggs. Under warm conditions, the eggs will hatch in 3-5 days.
The larvae feed for 3-5 weeks, progressively growing larger, until they pupate in the soil.
There are multiple generations in a year. These numbers vary depending on the climate. In North Carolina, most cutworms have 3-4 generations a year.
You can recognize these pests by their hairless bodies that curl up into a ‘C’ shape when disturbed. They are usually light colored, which makes them easily visible against the dark brown soil.
Till the ground
Since the cutworms live in the soil, tilling it can help to destroy the caterpillars. This is particularly important to do at least 2 weeks before you plant, so that you will eliminate cutworms that survived the winter in your garden soil.
Remove weeds and plant residue
Given their wide host range, you should eliminate any weeds near your tomato plants and remove any remaining crop residue.
Put collars around the stems of transplants
Experts recommend placing collars of cardboard or aluminum foil around the stems of newly planted tomato plants. Place the end of the collar a few inches into the soil, and place the other end several inches above the ground.
This is not failsafe, but it will deter most species of cutworms.
Use compost instead of green manure
The use of green manure could encourage the moths to lay their eggs in it. Compost is a much safer option when cutworms are a threat.
Monitor your garden closely
Since these pests can quickly cause extensive damage, you should frequently monitor for them. Go through your garden with a flashlight at night since this is when the cutworms are active.
Also, search the ground for brown droppings around your plants.
As with most other tomato pests, you can treat them with BTk or spinosad.
8. False Chinch Bug
This gray to light brown small bug is 0.12-0.15 inches or 3-4 mm long. Its nymphs are gray and have a reddish-brown abdomen. It occurs widely throughout North America and Mexico. Many other related species occur throughout the US.
This is obscure, but what caught my eye about the scientific name for the false chinch bug is “raphanus,” which is the scientific name for radish. That is fitting since this pest is often found on important weeds like wild radish and wild mustard.
Weeds adjacent to your tomato plants can serve as a source of false chinch bugs. If you grow mustard crops, they can also be a source of these pests.
Their populations will be much higher in years that received a lot of rain in the winter because weeds grow more vigorously after such weather, especially if the spring was cool and wet.
They overwinter on these weeds and then spread to gardens when the leaves dry out in the spring or are destroyed. Hot dry summers that follow cool wet springs provide the most favorable conditions for false chinch bugs to multiply.
You can frequently observe these bugs when they move around in the cool early morning or evening.
The false chinch bug has up to three generations per year. All stages of this pest can survive the winters under litter and on weeds in uncultivated fields. The bugs lay their eggs in or near soil around the base of host plants.
The larvae go through five stages until they reach adulthood.
False chinch bugs use piercing-sucking mouthparts to suck the sap from plants, including fruits, leaves, and stems. A large infestation can cause the leaves to turn brown and drop off. Seedlings or newly transplanted tomatoes are at particular risk.
These bugs sometimes feed on the green tomato fruits. You might not realize that your tomatoes have been damaged until you go to eat the ripe fruit and see the many small black spots.
If there are large populations of false cinch bugs that suddenly lose their food source, i.e., weeds, they can even migrate to and enter your house.
The severity of outbreaks can vary from year to year. If you keep the weeds around your garden under control, you are not likely to have major infestations from false chinch bugs. However, if you let the weeds grow and then suddenly remove them all, that can trigger a massive infestation into your garden.
If you just have a few tomato plants, you can stop an infestation by spraying your plants with water to knock the bugs off and drown them.
Grasslands or pastures that are adjacent to your garden can frequently serve as a source of false cinch bugs. Cultivating these areas may stop the bugs from migrating to your garden.
If you have a severe infestation on a lot of plants, you might need to consider an insecticide like spinosad.
9. Flea Beetles
- Pale-striped flea beetle (Systena blanda)
- Tobacco flea beetle (Epitrix hirtipennis)
These are just two of the many species of flea beetles that can afflict gardens, and they are perennial pests of tomato seedlings in most areas (in addition to a wide array of other plants).
Flea beetles are tiny black or brown beetles that range from 0.06-0.12 inch (1.5-3 mm) long. They get their name because they jump like fleas.
Their damage is unique, and all types of flea beetles cause similar damage.
Adult beetles feed on the leaves and generate many small holes (usually less than 1/8 inch), which makes the leaves look like sieves.
If the plants under siege have fewer than 4 or 5 leaves, flea beetle infestations can cause the plants to be injured during hot windy conditions. The plants dry out very easily because of all the holes in their leaves. Mature plants are much less likely to be severely injured by flea beetles.
Under rare conditions, the ripe fruit can be damaged by feeding. This can occur in very late-season plantings when the leaves are dying from maturity, lack of water, or infection by the fungus powdery mildew.
The adults survive the winter in leaf litter, hedges, and wood areas. They become active in early spring and lay eggs in soil, roots, small holes, or leaves.
The tiny white larvae feed on the roots of young seedlings, but they normally do not cause much damage. They pupate in the ground.
Adjust the planting time
Experts differ on their advice for when to plant tomato plants or seeds to make them less vulnerable to flea beetles.
Penn State University recommends planting seeds early, so the plants will mature more quickly and be less tempting to the beetles. In contrast, the University of Minnesota recommends planting them as late as possible.
Cover the plants with a row cover
Be sure to remove the row covers when the tomatoes are flowering or else the plants will not get pollinated, and you will not get any tomatoes!
Grow trap crops before your tomatoes
Growing a trap crop like radish before your tomatoes will lure the flea beetles in your garden, and then you can dispose of them before you plant your tomatoes.
Apply a thick layer of mulch
If at all possible, plant your tomatoes in an area where they were not planted before. This is also strongly urged as a way to protect against plant diseases.
Flea beetles can migrate from other hosts, but the damage will be minimal compared with that on tomato plants grown on ground with overwintering flea beetles.
You can protect your tomatoes from late-season damage by ensuring that your plants have a healthy canopy.
- Tomato hornworms (Manduca quinquemaculata)
- Tobacco hornworms (Manduca sexta)
Hornworms are enormous – for the size of the caterpillars (more than 3” or 7.5 cm long) and the amount of damage they can do. In fact, they are such a severe problem that they merit their own article!
Both types of hornworms are found throughout the US and cause similar types of damage. They usually eat the leaves and can entirely strip them from the plant. They generally do not feed on the fruit, but they can cause superficial scars on them when they do.
These caterpillars are green to reddish-brown with 7 or 8 stripes or V-marking on the sides and have a characteristic spike (horn) at the end of their body.
Read more about everything you need to know about hornworms in our complete guide ( Coming soon!)
- Tomato leafminer (Liriomyza bryoniae)
- Vegetable leafminers (Liriomyza sativae and L. trifolii)
Leafminers are pests that practically announce their presence. Their eggs hatch inside the leaves, and the larvae tunnel throughout them. This damage is visible as discolored swirling patterns on the tomato leaves.
The adults are tiny flies that are less than 1/10 inch (2.5 mm) long. The maggots can grow to 0.12 inch (3 mm) long and have a pointed head.
One nice change with this pest is that natural enemies normally keep their populations in check.
However, leafminer infestations can be a problem when the plants have been treated with insecticides to control other pests. In such cases, the insects can destroy all the yield.
Another problem is that bacterial or fungal plant pathogens can invade the tunnels and cause additional damage to your tomato plants.
If you will be growing tomato plants in the same spot, immediately remove the plants from your previous garden.
Keep your garden free of weeds in the nightshade family, which includes nightshade, horse nettle and Jimsonweed.
If the leafminer populations get high, you can purchase parasitic wasps to release in your garden. One highly effective parasitic wasp is Diglyphus isaea. This parasite is active in warm weather. It is most effective at temperatures from 75 to 90ºF and relative humidity of about 80%.
A single female wasp of this species can kill about 360 leafminer larvae. In addition to controlling leafminers in the genus Liriomyza, which includes the tomato leafminer, it can control 18 species from four different genera.
12. Lygus Bugs/Tarnished Plant Bugs
Lygus hesperus and L. lineolaris
Lygus bugs are a pest on at least 385 species of plants throughout the whole US. Fortunately, they are rarely a problem on tomatoes – expect for those grown in greenhouses.
The adults are about 0.3 inch (7-8 mm) long and can be yellow, brown, or green. What is noticeable about them is the triangle in the center of their back that can be tinged yellow, red, or brown.
The nymphs resemble the adults, but they are pale green and lack wings. They also have distinctive, red-tipped antennae.
These pests feed on seeds and fruits of many crops, including safflower and alfalfa. They prefer immature fruit and young developing tissue and suck out nutrients from the fruits, flowers, leaves, and stems.
The threat to tomatoes comes when these crops dry out and are cut or harvested, and the insects can then migrate to your tomato plants.
Symptoms on tomato plants include the characteristic black spots they leave in their path and damage to the fruit that can include catfacing.
If you are going to use your tomatoes to make juice or paste, you do not need to worry about lygus bugs.
These pests overwinter as adults and can be found in sheltered areas like long dry grasses, between the leaves of plants, in leaf litter, and under bark.
The nymphs have five stages, and each new generation of adults appears after 30-45 days or so. Lygus bugs have several generations a year.
Control in Your Garden
Frequently weed around your tomato plants. Weeds like pigweeds and dandelions can host enough lygus bugs to cause an infestation on tomatoes.
Control in Greenhouses
One quick step you can take is to prevent the bugs from entering your greenhouse by putting a screen on the door.
Minimizing weeds around your greenhouse is an important step for control. However, the timing of this is critical. If you mow the weeds in the springs, that can drive these bugs into your greenhouse. It is better to mow during the fall to control lygus bugs.
If you do end up with an infestation in your greenhouse, there are promising biological controls.
The predatory pirate bug Orius insidiosus has been shown to suppress lygus bugs in greenhouse pepper operations, which suggests that this it should be effective for tomato crops. You can purchase pirate bugs to release in your greenhouse.
You can also apply the insect-killing fungus Beauveria bassiana.
Mites are insidious parasites. They are tiny arachnids (closely related to spiders) that can build up huge populations on tomato plants without your knowledge.
Often, the only clue that your plants have been infected is when the leaves turn yellow and start dropping from the plant.
Tomato russet mite (Aculops lycopersici)
These types of mites are so specialized for tomatoes that the name of the species (lycopersici) derives from the scientific name for tomatoes (Solanum lycopersicum).
You need a 14X magnifying class to see these creatures. By the time you see the damage to your plants and become aware of their presence, there can be hundreds of mites on the green leaves above the damaged bronze leaves.
They can also cause the tomato fruit to have leathery skins and not taste as good.
This pest can kill tomato plants if not controlled.
If your plants get infested for more than one year in a row, be vigilant about removing weeds like morning glory and nightshade plants.
One option you have is to treat the infested plants with sulfur dust. The product Bonide Sulfur Plant Fungicide is highly effective against these mites.
If you do go this route, do not apply the sulfur while the plants are blooming. A downside about using an insecticide to control russet mites is that you will also kill any natural enemies that are fighting them.
Fittingly, there are predatory mites that will attack the russet mites and suck out their juices. The most common ones are mites in the genus Amblyseius. Several species of these mites are commercially available and vary in their preference for temperatures.
Two-spotted spider mite (Tetranychus urticae)
The two-spotted spider mite is a pest on an enormous range of plants. It is a more typical mite in that it produces fine but visible webs on the underside of leaves of infested plants.
If the leaves of your tomato plants are stippled with yellow and become bronze in color, you should look under the leaves to see if there is webbing. Also look for tiny moving dots, which would be the spider mites. A magnifying glass will help you to identify them.
Spider mites are more likely to be an issue in dusty environments, and plants that are stressed for water are more likely to be susceptible.
In home gardens, spraying tomatoes with strong jets of water can help to reduce the buildup of these mites.
If they continue infesting your plants, insecticidal soaps or horticultural oils are options. One such product is Organic JMS Stylet Oil. Traditional insecticides can actually increase infestations by destroying natural enemies that may be present.
As with the tomato russet mite, predatory mites can serve as excellent controls of two-spotted spider mites. Amblyseius andersoni is one such mite that is used commercially to control these types of mites.
14. Potato Tuberworm
Potato tuberworms are typically only a problem when tomato plants are planted on an area that has previously been used to grow potatoes or if there are potato plants nearby.
The adults are inconspicuous moths with pink to white larvae that area ¾ inch. The larvae prefer to enter tomatoes at the calyx end. However, they can enter at any point of the tomato.
Aside from a web they spin over the entrance to their burrows, it is difficult to know when the fruit have been infested.
The only guidelines for control on tomatoes are to avoid planting tomatoes where potatoes have been planted or near cull piles or infested potato fields.
15. Stink Bugs
- Brown marmorated stink bug (Halyomorpha halys)
- Consperse stink bug (Euschistus conspersus)
- Redshouldered stink bug (Thyanta custator accerra)
- Say stink bug complex (Chlorochroa sayi and C. uhleri)
- Southern green stink bug (Nezara viridula)
These are just a few of the 250 species of stink bugs found in the US and the 5,000 or so found throughout the world. The ones listed are all commonly found in California, and the brown marmorated stink bug infests plants and homes throughout the country.
Stink bugs are members of the family Pentaomidae, which as you might expect has something to do with “five.” It refers to the five segments on their antennae.
Most of these insects wreak havoc on plants, while others are predatory and feed on other insects.
These are about ¾ inch bugs that can find their way into your daily life. I found one staring up at me from a container of blackberries purchased in Lompoc, California, and another in a bag of grapes.
While I really like insects and considered majoring in entomology for my Bachelor’s of Science, I will admit I was slightly intimidated to find these large creatures on my food. The grocery store was mortified when I told them there was an insect on my blackberries.
Effects on tomatoes
Stink bugs are not large pests of commercial agricultural operations, but they can inflict considerable damage on a home garden. In addition to directly damaging plants, they can also carry pathogens that they can introduce to their plant hosts.
Your first inkling that you have an infestation of stink bugs on your plants could be when your immature tomatoes are deformed from a viral infection. Another could be when your fruit unexpectedly decay.
If you look closely at your fruit, you can see dark colored pinpricks surrounded by a lighter area that remains green or turns yellow.
Your best at avoiding these pests is to carefully control weeds or alternate hosts near your tomato plants. Russian thistle, cheese mallow (Malva parviflora), blackberries, legumes and mustards are common hosts.
The most direct approach is to handpick them from your plants or use a butterfly net and put them in a bucket of soapy water.
I suggest that you not crush them because they can release a foul-smelling chemical to defend themselves. Hence, the name “stink” bug. In other words, “don’t stomp or beat on them.”
You can also plant companion plants nearby to attract the stink bugs, so they avoid your tomato plants. Suggested plants include garlic, chrysanthemums, buckwheat, or lavender
Insecticides are generally not warranted and are often ineffective.
Biological controls have been effective at controlling stink bugs, and the parasitic wasp Trissolcus basalis was introduced to California to control the southern green stink bug.
The brown marmorated stink bug, in particular, is notorious for massing at houses in large numbers.
You can try and prevent them from invading your home by blocking potential entry points on the outside of your house.
- Install weather stripping around air conditioning units, attic or chimney areas, and gaps in the foundation
- Replace or add screens
- Use caulk to fill in any holes
- Buy traps
If they have invaded your house, you can vacuum them up, but be sure to change the bag to eliminate their foul smell and don’t use a bagless vacuum cleaner.
- Onion thrips (Thrips tabaci)
- Western flower trips (Franliniella occidentalis)
Thrips are tiny (about 1/16 inch or 1.5 mm) and best seen with a magnifying glass. The adult thrips are light brown to pale yellow. The nymphs are even smaller and lighter in color.
They are found throughout most of the US.
The thrips themselves can cause severe damage to tomato plants. In addition, they can transmit tomato spotted wilt virus. This virus is particularly severe on tomato seedlings.
Once the thrips have acquired this virus, they can transmit it for the rest of their lives.
While the thrips themselves are difficult to see, they often leave trails of brown spots on the leaves, which also appear silvery.
Once you have identified their presence, you should remove any infected plants.
Fortunately, ladybugs and some birds can keep them under control.
Don’t plant your tomatoes next to garlic, onions, or cereals since very large numbers of thrips can build up on these crops.
You can deter them from attacking your tomato plants by using reflective mulches early in the growing season.
Neem oil is a good treatment to knock down the populations of thrips, which will increase the likelihood of the successful use of biological controls.
There are many predators that will attack thrips.
If you caught the invasion early, you can release the predatory mite Amblyseius cucumeris. Another predator of thrips is the mite Stratiolaelaps scimitus that reproduces more quickly than A. cucumeris under optimal conditions (77-85 ºF with relative humidity of about 70%).
17. Tobacco Budworm
Tobacco budworm is native to the US and is prevalent throughout the eastern and southwestern parts of the country and in California. It only overwinters in the southern states, although it can occasionally survive in greenhouses in northern climates.
However, this pest moves northward throughout the year and can be found in New York, New England, and southern Canada during the late summer. It is not considered to be a pest in the northern climates.
Tobacco budworm is also widespread in the Caribbean and found sporadically in South and Central America.
The caterpillars look like those of the tomato fruitworm except that the mature ones are smaller and slightly slenderer.
The young larvae are yellowish or yellowish green. The full-grown caterpillars are greenish and about 1.5 inches (40 mm) long. The older larvae can be cannibals and consume younger larvae.
The larvae will bore into the buds, flowers and tomatoes and feed on the tender terminal leaves, stalks, and leaf petioles.
These caterpillars are hard to kill, so it is important to control them early in the season.
Tobacco budworms will consume a very wide array of plants, including field crops like cotton, clover, alfalfa, tobacco, soybean, and flax. They also feast on array of vegetables, including tomato.
A tremendous number of plants can serve as hosts for the larvae. Favored hosts in Georgia include toadflax (Linaria canadensis), cranesbill (Geranium dissectum) in Mississippi, and cotton in Texas.
Tobacco budworm is much more likely to infest your tomato plants if a favored host like cotton is nearby.
Part of the reason that introduced pests pose such a threat to plants in the US is that their natural enemies are not present in this country, so they have free reign. In contrast, natives like tobacco budworms have many natural enemies.
- Polistes wasps
- Bigeye bug (Geocoris punctipes)
- Damsel bugs (species of Nabis)
- Minute pirate bugs (species of Orius)
These are insects that are highly specialized for their hosts and will lay eggs in them.
- Trichogramma pretiosum parasitizes eggs and has been shown to be effective in vegetable crops. It is commercially available.
- Cardiochiles nigriceps, which is also found in vegetable crops.
- Heliothis nuclear polyhedrosis viruses
- Such viruses have been used to suppress the populations of tobacco budworm on field crops and weed hosts early in the season.
- Fungi (i.e., Spicaria rileyi)
- A South Carolina study found that this fungus killed many more tobacco budworm caterpillars than the viruses.
Other management techniques
- Destroy weeds – Destroying weeds early in the season by mowing or using herbicides can limit the number of tobacco budworm larvae that can attack your tomato plants.
- Treat weeds with insecticides – This is another technique that can help control tobacco budworm.
- Remove tomato plants at the end of the season – Doing this will remove places where this pest can overwinter and should help to reduce the levels of infestation the next year.
18. Tomato Bug
Tomato bugs are not common pests of tomatoes, but they can cause severe damage if they infest your garden in large numbers.
These bugs are about 0.25 inch (6 mm) long. They have a light green body with long legs. The nymphs resemble aphids and look like the adult tomato bugs except that they are smaller and lack wings.
Both adults and nymphs move quickly and can significantly damage a tomato crop. They feed by inserting their piercing sucking mouthparts into leaves and stems. This causes the leaves to shrivel and die.
You can spot their damage by the development of yellow to reddish rings around the feeding sites. This may sound minor, but this feeding causes the stems to become weak and brittle.
This damaged tissue can break easily when touched, which can cause the blossoms and young fruit to drop – and the stems to break.
Tomato bugs are such infrequent pests that there has been little research on their control.
However, entomologist Dr. Jim Walgenbach of North Carolina State University suggests that organic pesticides that will control stink bugs would be likely to also control tomato bugs.
Neem, spinosad and pyrethrum can control the nymphs but have little effect on the adults.
19. Tomato Fruitworm
(formerly Heliothis zea)
In contrast to tomato bugs, tomato fruitworms are highly serious pests of tomatoes and many other plants. These pests feed on at least 16 cultivated plants and are also known as the corn earworm and cotton bollworm.
Unfortunately, tomato fruitworms are found from Canada to Argentina and all throughout the US. According to Penn State University’s Plant Village, tomato fruitworms “can be one of the most damaging pests of tomatoes.”
Part of what makes these pests so damaging is that once the larvae (caterpillars) enter your tomato plants, they are very difficult to control. They can render the fruit inedible.
You might not even know they are there until your fruit have become terminally damaged. There is no way you can sell tomatoes with this damage, and you definitely wouldn’t want to eat them.
The adults are light yellowish-olive or pale tan to medium brown moths. Their wingspan is about 1-1.3 inches (25-35 mm). The front wings usually have a dark spot in their center and a dark band around their tip that has a lighter band inside of it.
The larvae are caterpillars that are creamy white with a black head when they hatch. They grow darker as they age and vary from nearly black to yellowish green. These caterpillars are moderately hairy.
These insects overwinter as pupae in the top 1.5” (4 cm) of the soil and emerge in the spring ready to go on the offensive.
The pupae start out shiny and reddish-brown, but they become dark brown before the adults emerge. The females usually emerge first.
Unfortunately, there can be multiple generations of fruitworm each year. There are four generations a year in North Carolina.
The larvae crawl into the stem ends of fruits that are between 0.75 to 2 inches (2.5-5 cm) in diameter. Sometimes, the caterpillars will emerge from one fruit to enter another.
If your plants are infested late in the season, small larvae will also tunnel into ripe fruit.
Infested tomatoes have a watery, messy internal cavity that contains skins that have been cast off and frass (excrement).
Fruit with this damage will ripen prematurely.
Tomato fruitworm caterpillars can also bore into the midribs or stalks and feed on the leaves in the buds as they develop.
This can cause visible damage in the form of distorted leaves.
Monitor Infestations to Stop Them in the Early Stage
It is critical to scout for tomato fruitworm eggs and small larvae to intercept the infestation before large numbers of larvae enter the tomatoes. Once inside, they are protected from sprays.
There is less of a problem if you harvest your tomatoes early in the season. Late-season crops can be seriously affected.
You should consider purchasing traps that have a pheromone (mating hormone) specific for tomato fruitworm. When you see moths, you should start looking for eggs.
Please note that this company sells this trap as one for corn earworms. Don’t worry – that is another name for tomato fruitworm.
Another factor to consider when you should start looking for eggs is when your plants have many green fruit that are 1” (2.5 cm) in diameter.
Identifying the eggs will let you know whether your plants are developing a tomato fruitworm infestation, so knowing what they look like is critical.
The eggs are almost like spheres, but they have a flattened base. Look for them on the upper parts of your tomato plants on both the upper and lower surfaces of leaves.
They are creamy white when they are first laid. However, they develop a reddish brown band after 24 hours and become darker right before they hatch.
Tomato fruitworm eggs are easily confused with cabbage looper eggs. However, the looper eggs have finer grooves on them.
In one sense, nature may be on your side with tomato fruitworm infestations. Since this pest is native to the US, many beneficial insects will attack the eggs or larvae.
If there are many natural predators, you might not need to worry about your tomatoes being attacked by tomato fruitworms.
The eggs will show classic symptoms if they have been parasitized. They will turn black!
This strategy is not perfect. There can be a delay before the eggs turn black, so you could overestimate the number of viable eggs.
Control of the eggs
There are predatory wasps (Trichogramma pretiosum) that are highly effective at parasitizing tomato fruitworm eggs.
Since you have a backyard garden, it is highly unlikely that you will have acres of tomato plants. However, just to give an idea of how successful these wasps are in commercial fields, 100,000 of them are released per acre of tomato plants.
Control of the larvae
The bacteria BT are highly effective at killing the caterpillars, although you need to treat the larvae before they burrow into your tomato plants.
Another option is to use the organic insecticide spinosad. However, that can do more harm than good if you have many natural predators or parasitoids on your plants.
Keep an eye out for bigeyed bugs and minute pirate bugs (Orius insidiosus) that are also effective at controlling tomato fruitworm.
20. Tomato Pinworm
A severe infestation of tomato pinworms can seriously damage the leaves of tomato plants and infest almost 100% of the fruit.
Luckily for northern backyard growers, tomato pinworms are primarily problems in greenhouses from Mississippi northward. These pests can only overwinter in Texas, Hawaii, Florida, and southern California.
This insect is specialized for members of the nightshade (Solanaceae) family. That includes tomato, eggplant, and potato plants. Solanaceous weeds like horse nettle, Jimsonweed and nightshade can also serve as hosts.
Tomato pinworms get their name from the damage they leave after the larvae bore into the buds, fruit, and stems. They leave tiny holes on the surface that look like pinholes.
Unfortunately, these insects can have many generations a year – as many as seven to eight in Florida. A generation can be as short as 26-34 days in the summer, but they take longer in cooler weather.
The adult stage of this insect is a small gray moth with a reddish-brown and mottled thorax and head. Its body is about ¼ inch (6 mm) long, and its wingspan is 1/3 to ½ inches (9-12 mm).
These insects lay miniscule oval eggs on the bottom of the leaves that are about 0.016 inches long (0.4 mm). The eggs are light yellow when they are first laid and then turn pale orange. You can find them on the lower leaves of your tomato plants.
The caterpillars are yellowish-grey and also very small (0.3 inches or 0.8 mm). The mature larvae can be green, ash gray, or yellow and have distinctive dark purple spots. They are about ¼ inch (6.5 mm) long on average.
The larvae pupate in the soil and gradually change from green to brown. The ¼ inch (6 mm) long pupae have distinctive webs of loosely woven silk that become covered with soil particles.
Infestations with tomato pinworms become more severe as the season advances. The most intensive damage occurs when the plants are grown from early in the season to late fall.
There are several different symptoms that show that your plants are under siege by tomato pinworms.
The young larvae tunnel through the leaves and leave trails like those of leafminers. One difference is that the tunnels gradually become one large blotch.
Some of the older caterpillars emerge from the mines and then fold leaves and create a web. This protects them and provides a place to feed. Others bore into the plant and leave the characteristic pinholes described above.
Discolored blotches on your tomatoes are another sign that tomato pinworms are active in your garden. Unfortunately, when the pinworms feed in the tomatoes, they can also introduce pathogenic bacteria that make your fruit rot.
Prevention and sanitation
These are the most practical strategies for a backyard gardener.
Prevention is always a good strategy! If you buy your tomato plants, inspect them closely to make sure that they are not infested.
Practicing good sanitation will also help reduce the likelihood of infection. Remove any weeds in the nightshade family, which includes nightshade, horse nettle, and Jimsonweed. Also, destroy all the remains of your tomato plants after harvest.
Several parasites can be used to control tomato pinworms. Recommend controls include the species listed below. Unfortunately, I cannot find commercial sources for them
- Species of Apanteles
- Parahormius pallidipes
- Sympiesis stigmatipennis
Disrupt mating with pheromones
Pheromones can be used to bait traps, so you will be an alerted when a pest has entered your garden.
However, they can also be used to flood the area with the mating hormone. This swamps out the hormones produced by the moths that are trying to mate, and they cannot find each other. This strategy is often used to reduce the populations of tomato pinworms.
Unfortunately, the pheromones are very expensive, so they are only practical for commercial growers.
21. Tomato Psyllid
In some states, tomato psyllids are considered to be the greatest threat to tomato plants. They are problems west of the Mississippi.
These sap-sucking insects resemble miniature cicadas and can quickly jump from plant to plant. They affect a wide range of plants and can shelter on many of them. However, they prefer those in the nightshade family.
Among tomatoes, they prefer the yellow pear tomato.
Their feeding damage would be bad enough. However, they also produce a toxin in their saliva that can substantially damage the tomato plants:
- Transplants die.
- The leaves turn yellow and fall off. (“psyllid yellows”)
- The plants are stunted or can wilt and die.
- Either no tomatoes are produced or if the plants are larger, they produce many very small tomatoes.
These psyllids transmit a severe bacterial pathogen known as Candidatus Liberibacter solanacearum. This makes the damage even worse.
They also excrete wax-coated sap that attracts ants and can cause the fungal disease sooty mold.
As noted, the adults resemble cicadas. These tiny insects are about 0.12 inches (3 mm) long. The adults have clear wings, lines on their abdomens between segments, and yellowish or white markings on their thorax.
They typically lay tiny eggs on stalks on the bottom sides of the leaves and along the leaf margins. You will probably need a magnifying glass to see the eggs. They are white when laid and then turn yellow within a few hours.
The nymphs have what look like scales on their bodies. This phase is yellowish green to orange. The insects have three pairs of short legs and red eyes.
How to distinguish tomato psyllid nymphs from those of whiteflies?
The nymphs can be difficult to distinguish from those of whiteflies. Here is how to tell the difference:
- They are green and fringed with hairs.
- They have wing buds.
- If you disturb them, they will move. (Whitefly nymphs cannot move.)
Put yellow sticky cards near the top of your tomato plants. If you find tomato psyllids in the trap, examine the leaves of your plants very closely. If you find adults, you should consider treatment.
This is a difficult pest to control. If you have them on your plants, you should consider contacting your USDA (United States Department of Agriculture) county representative. You can find out who this is by entering your zip code at this site.
Silverleaf whitefly (Bemisia argentifolii or B. tabaci)
If you have been gardening for any length of time, you are probably well aware of whiteflies. Bumping an infested plant can result in an intense cloud of tiny white flies, hence, their name.
You can also easily spot them on your tomato plants because their white color stands out against the green leaves or red fruit.
Do not let their tiny size fool you! You wouldn’t think that an insect that is about 1/32 inch long could be such a menace.
There are more than 1,500 species of whiteflies in the world. It might seem like a good thing that only a few species cause damage on tomato plants.
Unfortunately, the primary whitefly that afflicts tomatoes, the silverleaf whitely, can cause extensive damage to your tomato plants. A severe infestation could force you to remove your tomato plants for the rest of the season.
This pest is unusually complicated, and recent research suggests that this “species” is actually a group of 40 or more different species.
Silverleaf whiteflies occur in subtropical and tropical areas throughout the world. They are also found in greenhouses in temperate areas. In the US, this species has been found in all the southeastern states and Texas, Maryland, DC, California, and Arizona.
Appearance and Lifecycle
The adults look like tiny moths. Silverleaf whiteflies are slightly smaller and more yellow compared with other types of whiteflies. They hold their wings in a manner that makes them appear to be more slender than other commonly found whiteflies.
The young stages start out as “crawlers.” After hatching, they crawl on the bottom of leaves until they settle down to feed. The crawlers molt and then produce nymphs that look like scale insects. Regrettably, they continue to suck out sap.
The nymphs will molt two more times and then become a pupa that does not feed. These pupae give rise to the adult whiteflies.
Normally, each female will produce about 80 to 100 eggs. However, a strain that was extensively sprayed with insecticides has been reported that can produce 300 eggs per female.
These insects can infest an extensive number of host plants, including legumes, cucurbits, mints, crucifers, roses, and solanaceous plants among many others. This makes them almost omnipresent!
The hosts in the southeastern US that have been reported the most frequently include tomato, gerbera daisy, and poinsettia.
The primary damage occurs from sucking the plant’s sap. The adults, crawlers, and nymphs all suck their host’s sap.
Yellow spots can appear at their feeding sites, and if there is heavy infestation, the plants can wilt.
Even worse – silverleaf whiteflies that feed extensively can infect your plants, make curling leaves with the damaging viruses Tomato yellow leaf curl and Tomato mottle virus.
A side effect of their feeding can be the growth of sooty mold.
Putting reflective mulches around your crop can help to divert the whiteflies from your plants.
Make sure you examine your plants closely for whiteflies, so you can quickly take action before the infestation spreads throughout them all.
Your first step if you find whiteflies is to quickly prune any infested leaves and remove them from your garden!
Many predatory insects feed on whiteflies, including lacewings, ladybugs, hoverflies, and parasitic wasps. They are found naturally, and you can buy them to release onto your plants.
This is a key reason to avoid using insecticides.
It is difficult to control silverleaf whiteflies with insecticides because the older immature forms and eggs are resistant to many types of them. Also, the adults are highly resistant to the residues of dry pesticides.
You also need to make sure that you treat the surfaces of the lower leaves.
Neem oil is less toxic than some of the commercial pesticides, but it has some advantages:
- It is toxic to the young nymphs.
- It is also effective against older nymphs and can inhibit their growth.
- Another factor is that it reduces the ability of the adults to lay eggs.
Wireworms look similar to cutworms, but they are the larvae of click beetles.
These insects are entirely soil pests.
They can feast on an enormous array of plants, but the stems of tomato transplants are one of the most frequently attacked.
There are many species of wireworms, but they all cause similar damage – they eat holes in the roots of their hosts. They then tunnel up through the stem.
These pests get their name because the larvae look like wires. They are known for their hard bodies that can be yellow-gray, cream, or white. Their head capsule is red-orange.
The larvae can live in the soil for up to six years depending on the species!
The adult click beetles are distinguished by the clicking sound they make when they lay on their backs and try to get upright by jumping into the air.
The eggs are small, white and oval.
All types of wireworms overwinter as adult and larval stages in the soil. The adults emerge from the soil when its temperature warms up in the late spring. They then lay eggs in damp soil.
The larvae feed on plant roots until they pupate at least one year later. The pupa becomes an adult beetle in about a month and remains in the soil until the next spring.
Because their generations overlap, there can be all ages and sizes simultaneously present in the soil.
Wireworms can injure crops in several different ways:
- Eating seeds in the soil, which prevents the seedlings from growing.
- Cutting off small stems and roots that are underground.
- Boring into the roots and larger stems of transplants.
The early feeding causes shallow holes. However, late feeding produces characteristic ragged, deep holes. Wireworms can introduce 10 or more holes to a single root.
Often, they then inch up the stems.
Do not plant in infested soil
If you know that wireworms are a problem in an area, plant your tomatoes as far away as possible or plant them in containers.
Do not plant in soil that was sod
These pests are very prolific in sod (grass), and they can quickly switch to eating the roots of your tomato if you plant them in this soil.
You can lure the wireworms by burying germinating corn, beans, or peas or stiff dough in 2-4 inch holes and then covering them with boards or tiles.
Dig them up every 3 to 5 days and destroy any wireworms you find.
Fully grown carrots are another good bait to use. Plant them every 3 feet in your garden and then pull them up after 3-5 days, kill the wireworms, and replant the carrot plants.
Improve the drainage
Several types of wireworms thrive in poorly drained soils. Improving the drainage will help to reduce the numbers of wireworms.
Don’t plant your tomatoes next to ornamentals
Dahlias, gladiolus, phlox, and asters will attract wireworms. Therefore, place your tomato plants as far away as possible from such plants.
Turn over the soil in the fall
Once you have removed the tomato plants, dig up the beds. Many types of birds eagerly feed on wireworms, so they will eat any they find.