14 of the Worst Garden Pests and How to Control Them
Gardening brings you endless joy, wonderful meals, and beautiful flowers. But it can also be a challenge. Every garden, no matter how well maintained, comes with garden pests that want to eat your vegetables and destroy your blossoms.
There are more pests out there than we could cover in one article, so we’re covering the most common and most destructive ones. If you’ve got ragged leaves or your plant is looking miserable, read on to find out if one of these creatures is the culprit, and how to deal with it.
Aphids are perhaps the most widespread garden pest and affect everything from vegetables and fruit trees to your favorite flowers. There are few plants that aren’t susceptible to these tiny insects.
Aphids are tiny (1/8 inch long) sap-suckers that can cause leaves to wilt and discolor. While they may be small, they live in colonies, which makes them easier to spot. A heavy infestation can cause the plant to be stunted. In addition, they can spread viruses.
They come in a wide range of colors but are typically green. There are many different aphid species and some will feed on a certain plant. For instance, is an aphid that eats melon plants and is common in the southeastern United States.
They’re worse in spring and early summer but live all year on houseplants and in greenhouses.
Fortunately, aphids are easy to kill. They have soft bodies and not much protection. There are many homemade recipes using soap or oil to smother them. You can also use products like Safer Soap and neem oil.
Ladybeetles and green lacewings are natural predators of the aphid. Encourage these beneficial insects in your garden. You can also purchase them from garden supply companies to release on your property.
Whiteflies are another common pest. They particularly like warm, humid environments like greenhouses. They’re especially drawn to tomatoes, as well as squash and cucumbers.
As their name implies, they look like tiny white flies. They like to hide beneath the leaves of plants, which they suck the juices from, causing leaves to become discolored. If you shake the plant, the whiteflies will fly up into the air before settling on your plants again.
Like aphids, whiteflies are responsible for transmitting plant viruses. They live all year in your greenhouse or on houseplants, and in warm southern and coastal climates. Outside they hang around from spring to fall.
Use yellow sticky traps to catch the adults. Safer Soap and neem oil both work well to kill them.
Beneficial insects such as lady beetles and lacewings will also help keep populations under control. The whitefly parasite in particular is ravenous for the nymphs and pupae.
3. Colorado Potato Beetles
I wish the Colorado potato beetles stayed in Colorado, but they don’t! They’re found throughout the United States. They target members of the nightshade family such as potatoes, tomatoes, eggplants, and peppers.
The grubs of Colorado potato beetles chew the leaves of plants. On the bright side, since they are large, they’re easy to spot crawling around your garden.
The adults are a yellow-orange color with black stripes and are 1/3 an inch long. The young caterpillar larvae are reddish and turn more orange as they grow. They have black heads and black spots down the length of their bodies.
The adult beetles spend the winter hibernating in your soil, and in spring they come out and lay eggs on your lovely garden transplants and potatoes seedlings. That’s why it’s crucial to control them in the fall and winter.
The Colorado potato beetle is one of the hardest garden pests to kill. The adults have a hard exoskeleton that protects them from insecticides. In addition, they can develop insecticide resistance within a generation. So it’s essential to employ multiple methods when trying to lower the population.
Start by planting resistant varieties. Mulch susceptible plants with straw a least three inches thick. You can bribe your children to hand pick the adults and drown them in soapy water. Monterey Garden insect spray and BotaniGard are effective pesticides.
4. Cabbage Looper and Cabbage Worm
The lopper is a native species, and the cabbage worm is an invasive species. Both can be quite destructive because they’re voracious eaters of plants in the brassica family, which includes cabbage, broccoli, and kale.
Both the cabbage looper and the cabbage worm are widespread throughout the U.S. They start as eggs that the parent lays on the underside of leaves. The larvae hatch and begin to feed on the plant. They will also burrow into cabbage heads leaving a trail of excrement behind them.
Sometimes referred to as inchworms, loopers are pale green caterpillars about 1/2 inch long. They’re the larvae of grey nocturnal moths.
The cabbage worm, on the other hand, is a green fuzzy worm that crawls over the leaves of your plants, eating as they go. The adults are white or pale yellow butterflies.
You may notice butterflies and moths flitting around your garden from spring to fall. If so, check your plants for loopers and worms.
Fortunately, these caterpillars are a favorite snack for birds. Your chickens and ducks will love them, as will the local songbirds. You can place birdhouses near your garden to attract hungry songbirds such as bluebirds and warblers.
When you transplant your brassica crops, use floating row covers to protect your plants and keep the butterflies and moths from laying eggs.
Diatomaceous earth is another option for controlling caterpillars. You can also pick them off by hand and either feed to the birds or drown them in soapy water.
5. Tomato Hornworm
The tomato hornworm loves tomatoes of course but also potatoes, peppers, eggplant, and tobacco.
Hornworms are scary looking! They’re a large caterpillar that grows to four inches long. They are green and have diagonal white strips along the body, and a black or red horn projecting from their butt.
The hornworm’s parents are the beautiful sphinx or hawk moth. They come out in full force in mid-summer and hang around until frost.
These large caterpillars are easy to pick off and dispose of. My father used to pay us a penny a worm to peel them off his tobacco plants and drown them in a bottle.
I would then proudly save my money until the next chance to go to the country market and buy candy!
The hornworm has a deadly enemy in the Trichogramma wasp. These beneficial insects lay their eggs inside the hornworm.
When the eggs hatch the larvae feed on their host and then make cocoons that are attached to the body of the hornworm. If you see this in your garden leave the hornworm alone. It’s already dying as the young wasps are metamorphosizing.
6. Corn Borer
The corn borer’s favorite midnight snack is corn, but it will also eat apples, beans, tomatoes, and gladiolas.
In corn, they begin by eating leaves and tassels. As they get older, they will burrow into the corn, eating both stalks and ears. In addition to making the ears a gooey mess, the borer makes the plant weak, and it may fall over.
The larvae are about an inch long and translucent cream color with a dark head and spots along the side. Parents are a small nocturnal yellowish-brown colored moth. You’ll spot them during the summer months.
Don’t leave corn stalks on the ground over winter. Clean them up or let the cows eat them.
Encourage or purchase predatory Trichogramma wasps. Spinosad products such as Monterey Garden insect spray will kill larvae.
7. Slugs and Snails
Slugs and snails are horribly destructive. There are a variety of different snail and slug species out there, from the French native brown garden snail to the greenhouse slug.
They’re voracious eaters that can devour a garden full of seedlings in one night. These pests primarily eat herbaceous and young plants.
Slugs and snails are most active in the evening or on cloudy, foggy days. You’ll often first know you have them when you see the jagged leaves of your plants. If you see a silvery slime trail, you can be confident snails are lurking nearby. Check under leaves, low edges on fences, and other hiding spots to confirm.
You’ll want to take a multi-pronged approach to control these common garden pests. Hand picking is the first line of control. Go outside in the evening every night and dispose of as many as you can find. Once the population is reduced, you can do a weekly check.
You can also use traps and erect barriers. Of course, there are also plenty of poisons you can use, as well as beneficial predators like birds and the Staphylinid beetle.
8. Spider Mites
Spider mites are incredibly common and most destructive in greenhouses or indoors. Mites are technically arachnids. They live in large groups and feed by piercing the plant and sucking out its juices.
You’ll most often find mites in hot, dry areas, particularly those where natural predators have been killed off by the overuse of insecticides. They can travel on the wind, so they spread quickly.
You usually won’t notice spider mites right away. Instead, you may see their fine webbing and your plant leaves will show spots and stippling.
The pests themselves are about the size of the tip of a pin and are reddish brown.
Mites are resistant to pesticides, and pesticide use tends to kill off the good bugs that snack on mites. The best way to get rid of them is to prune away infested areas and then blast plants with a strong spray of water. Encourage ladybugs and lacewings, which are natural predators.
If you really need to get serious about an infestation, spray plants with neem oil or insecticidal soap for a few weeks.
Cutworms are no fun. They’re the larvae of several moth species that overwinter in the soil and then emerge in the spring to eat your plants. These garden pests cut off a plant at the base near the soil by nibbling through it.
Look for cutworms in the early morning and evening. You can’t really identify them from other caterpillars by their coloring, because they can be pink, green, or black, and solid, striped or spotted. They’re about 2-inches long.
The easiest way to know you have them is when you notice the distinct damage they cause.
The best way to stop cutworms is to put cardboard plant collars around your plants. You can also go out in the evening or on a cloudy day and hand pick these garden pests.
For an added layer of protection, sprinkle diatomaceous earth around your plants. Encourage birds and fireflies to hang around your garden, because they’re natural predators.
10. Leaf Miner
Leaf miners don’t just cause unsightly damage to your plants. They can destroy them to the point where they can fail to thrive. These garden pests eats its way through the mid-tissue of the leaves, and they can skeletonize your plants rapidly.
There are many different types of leaf miners, but the damage they do is the same.
You probably won’t notice leaf miners in your garden. They look like tiny black flies, but the larvae are what cause the damage. They chew long trails that look like squiggly lines through the leaves of your plants.
Leaf miners are fairly easy to control. You can pinch plant leaves along the tunnel to squish them. You can also spray plants with neem oil on a regular schedule. Encourage natural predators to hang out in your garden, as well.
Scale is particularly troublesome for houseplants. These garden pests suck the life out of your plants, causing them to fail. They’re damaging at every life stage, and they leave behind a honeydew secretion that can attract disease.
Scale are most common in warm, dry environments. Look for a small, tan, oval lumps on the undersides of leaves or at leaf joints. The males are tiny flying bugs.
If you have a scale infestation, prune out the infected parts of the plant and scrub any remaining bugs away with a soft brush and soapy water. Then, spray plants with neem oil regularly. Finally, encourage natural predators.
12. Tarnished Plant Bug
Tarnished plant bugs suck the life out of veggie and fruit plants, leaving black spots on stems, leaves, shoots, and flowers. They also carry diseases. Even worse, you can have five generations of the pest each year, so they can quickly overwhelm a garden. They attack about half of the crop plants grown in the U.S.
The adults are a quarter of an inch long and are brown with yellow, bronze and red markings. The nymphs are yellow-green and wingless. If you see black spots or catfacing on your tomatoes, examine your plants thoroughly to spot these garden pests.
Floating row covers are the most sure-fire way to stop tarnished plant bugs from wrecking your harvest. You can also use white sticky traps to capture them. Encourage natural predators and keep your garden weeded for an added layer of organic control.
13. Japanese Beetles
Japanese beetles are indiscriminate garden pests that do a shocking amount of damage to crops every year. They skeletonize leaves and can destroy a crop.
Japanese beetles are kind of beautiful if you can overlook their destructive nature. They have iridescent blue-green heads, copper backs, and tan wings. They’re about a half inch long, and you’ll see them emerge from the soil as adults in June.
Use floating row covers during the spring and get serious about hand picking the beetles off of plants, since this is the best way to control them. Drown them in soapy water with a bit of neem oil added. You can also put a drop cloth under plants and then shake the plant. Roll up the cloth and dump the beetles in soapy water.
Japanese beetle traps are also a good option.
14. Flea Beetles
I saved the worst for last, in my opinion anyway. Flea beetles are my biggest enemy! They can make an eggplant leaf look like a lace doily overnight.
Flea beetles are notorious feeders of young seedlings and transplants including beans, cabbage, corn, eggplant, potatoes, peppers, and tomatoes.
Another reason to hate this garden pest – they transmit both bacterial and viral diseases among your plants and can bring in things from nearby gardens.
Flea beetles are tiny jumping insects that can move quickly throughout your garden. Adults have a hard black exoskeleton that makes them difficult to kill. The larvae are small thin yellowish and worm-like. They live underground and feed on the roots of your plants. They love the hot sunny summer weather.
Be vigilant! Winter garden clean up is essential as they will winter over in your soil. Floating row covers are excellent barriers for flea beetles but make sure you securely tuck in the edges. Yellow sticky traps are good for catching adults and monitoring populations.
Neem oil and BotaniGard are two good organic insecticides for controlling flea beetles.
Gardening is a pleasure. I love nothing better than being out in my garden and puttering around. But protecting your plants from garden pests is key to having a successful harvest. Try a variety of natural options to keep your garden pest free.
Was this article helpful? Yes No