While every gardener has to deal with garden pests sometimes, no one wants to watch an infestation tear apart their plants. One problem is that many commercial pesticides contain harmful toxins that can actually make the problem worse. They kill off all bugs, including beneficial insects that help your plants.
Rather than reaching for these chemicals to snuff out unwelcome visitors, try an organic method to eliminate common garden pests. These cures may not always work as quickly, but they will help you learn to manage menaces without harmful chemical poisons.
Use the following list as a guide to figure out which destructive critter is the culprit of your garden woes. We offer up natural ways to eliminate each of them, and protect your garden from further damage.
Caterpillars are ravenous beasts that enjoy fruits, veggies, ornamentals, and shade trees. Most species are harmless to people, but can completely destroy a garden or houseplant overnight. They devour leaves, destroy stalks and stems alike, and some even tunnel into certain fruits.
The easiest way to deter caterpillars is to encourage predators like birds to join your yard. Do this by adding in a birdbath, bird house, or feeders. Chickens are also fond of caterpillars, and there are plants like aster, yarrow, cilantro, or dill that will attract predatory insects.
Instead of spraying chemicals, pick the pests from your plants. Relocate them somewhere else (a wooded area nearby), or drown them in a bucket of water.
For bad infestations, try spraying your plants with pyrethrins (a natural pesticide that’s safe for pets and humans). You can also make your own spray using a quart of water and two tablespoons of insecticidal soap, and spritz it directly onto the critters.
These tiny, pear-shaped bugs are sometimes known as plant lice. There are many aphid species, and this common menace feeds on the sap of a variety of flowers, plants, fruits and vegetables including:
- Shade trees
You may have aphids if you notice the foliage of your plant appears distorted. New growth might come in deformed, foliage appears to be covered in sooty mold, and leaves drop. Aphids will feed on the underside of a leaf, where you may look for them in large groups. They can demolish a plant in just a couple of days.
To prevent aphids from attacking your plants, entice insects that feed on aphids by adding flowering plants like marigolds, daisies, and sunflowers to your garden. Ladybugs (ladybirds) are perfect for the job, but aphid midges and lacewings work as well. You can also try covering the plants with protective floating row covers, or repel pests using a hot pepper or garlic spray.
For removal, try spraying the critters with a strong blast of water from the garden hose. You can also easily squish the bugs by hand, or use organic insecticidal soap, horticultural oil, or need oil to quash an infestation.
These small, fluffy bugs look similar to white cotton. They tend to target indoor plants and can multiply very quickly, sucking all the sap from your plants in a matter of days. Because this severely weakens the plant, they can become yellow, feel sticky, drop leaves, and keel over.
Protecting your plants with a cover is the easiest way to prevent infestations, but infestations must be dealt with quickly. These insects tend to hang out on a plant’s stem joints or under the leaves, and you can blast the bugs away with a strong shot of water.
To kill mealy bugs, spray them with a mixture of water and liquid insecticidal soap. Additionally, conduct spot treatments by using a cotton ball soaked in rubbing alcohol to dab and rub the pests away. You can also buy a mealy bug predator called the mealybug destroyer (Cryptolaemus montrouzieri) from your local garden shop.
Prevent future infestations by making your yard more attractive to insects that feast on these garden pests, like lacewings, wasps, and hoverflies.
Perhaps one of the most destructive garden pests, cutworms are fat, inch-long worms that can fly as moths by night. You’ll find them in the topsoil of early flower and vegetable seedlings, and they chew through the stems at ground level, devouring plants in May or June. They especially like tomatoes, kale, broccoli, and cabbage.
Control cutworms by delaying planting until mid summer, and make sure you practice smart crop rotation to protect your plants. Bait these pests using cornmeal or wheat bran and remove them by hand, or try adding nematodes to the soil.
5. Cabbage Maggots/Worms
If you’re cultivating any brassicas in your vegetable garden, you’ve probably run into these highly destructive maggots. This is especially true if you live in North America. These light green jerks kill plants quickly, tunnelling in roots and creating pathways for diseases to enter. They attack all brassicas, obliterating broccoli, kale, cauliflower, turnips, and Brussels sprouts in their path.
You can prevent these maggots by covering your cabbages with floating row covers until harvest time, and burning any roots from plants you’ve already harvested. Try also hanging birdhouses around your garden to attract birds that enjoy these worms as dinner.
If the infestation is severe, pick off the pests by hand and try a bacillus thuringiensis-based insecticide.
There are several harmful beetles that attack plant life and vegetable gardens in particular, including:
- Colorado Potato Beetle: As the name suggests, these beetles are often found on potatoes, eggplant, and tomatoes throughout North America. Spraying them with neem oil is effective.
- Mexican Bean Beetle: They look similar to ladybugs but enjoy attacking beans. Get rid of them with neem oil or insecticidal soap.
- Japanese Beetle: Commonly found east of the Mississippi River, and can be treated with insecticidal soap.
- Asparagus beetle: Found on asparagus plants, these beetles damage even next year’s crop and are controlled using neem or Spinosad-based products.
- Cucumber beetles: Affect the entire cucumber family, including melons, pumpkins, and squash, and are controlled using organic pesticides containing Spinosad.
Note that the tiny flea beetle is one of the most intrusive critters to infest crops in North America. They’re found on vegetables, and can jump from plant to plant like a flea. The adults will chew small, round holes in leaves while larvae feed on the plant’s roots.
Young plants are particularly susceptible to flea beetles, but they especially affect corn, nightshades, and brassicas.
Prevent beetles in your vegetable patch by using floating row covers until harvest time, and rotate your crops between plantings. To kill them, spray your plants using a garlic, hot-pepper, or kaolin spray. You can also try nematodes to control the larvae.
7. Vine Weevils
Vine weevil larvae and adults attack indoor and outdoor plants alike. They wreak havoc in the garden by eating leaves during summer months, and attacking the roots just like the flea beetle. The black-hued adults feed at night and hide in the soil during the day. The larvae, however, cause the most damage by tunnelling through and eating the roots.
Because these garden pests prefer moist soil, only water plants when needed, and remove hiding spots around the plant, such as excess mulch. It’s best to kill off the bugs before they can lay their eggs by hand-picking them from plants and throwing them in a bucket of soapy water.
If this doesn’t work, try using nematodes to kill off the infestation. Nemasys Vine Weevil Killer is a popular choice, and it’s available at most garden centers.
8. Garden Slugs and Snails
Slugs and snails come in various species—all of which can terrorize a garden and even invade your home at times. They enjoy low-hanging plants in shaded, moist environments, and in addition to harming your plants, they’re toxic to pets as well. You can typically spot these nocturnal fiends by the slimy trail they leave in their wake, and they enjoy just about any type of seedling of various plants and veggies.
Prevent these slimy creatures by only watering your plants in the morning, and encourage birds, snakes, frogs, or toads to eat the pests. You can also place copper strips around your plants, then remove the critters by hand and drop them into soapy water.
Organic products like slug baits use an ingredient called iron phosphate to actively tackle your pest problem, but avoid baits with metaldehyde or methiocarb. These are highly toxic to pets and wildlife. Remember the chain of life: if you use harmful poisons to kill your slugs, and then beneficial animals like hedgehogs eat them, they’ll likely die too.
…as will carrion animals that’ll eat them in turn. And so on.
These garden pests tunnels through leaves, feeding on tissues and leaving discolored trails behind. “Leafminer” is a generic term used for the larvae of various types of flies, and the damage they cause is typically cosmetic. Common plants they attack include chard, spinach, beets, and blueberries.
Prevent further infestations by removing damaged plant leaves and covering veggies with floating row covers. Flowering herbs may also be used to attract insects that feed on leafminers. Although this pest is hard to control using products, neem oil or Spinosad-based products can help.
10. Spider mites
Because these web-spinning mites can quickly devastate an indoor or outdoor garden, infestations require fast action. They suck the life from the plant’s foliage, which can leave yellow stippling on the leaves, and leaf drop.
Prevention methods that work best include washing plants thoroughly, and minimizing both water and nutrient stress whenever possible. However, existing populations need immediate treatment by spraying an organic solvent such as neem oil or horticultural oil directly on the bugs. Predators like ladybugs, assassin bugs, or green lacewings may also help.
Several other common garden pests can infest veggies and houseplants alike. While there are many offenders and cures for each, the best course of action is to know and understand which pests are attracted to your plants ahead of time, so you can prevent infestations before they get out of hand.