Worst Garden Pests (And How to Get Rid of Them)

green aphids eating a leaf

The list of common garden pests is a long one, and their popularity depends on the region you live in and the plants you grow.

This list by no means tackles every single plant destroyer out there, but we've scaled it down to the very worst garden pests that seem to do the most damage in American gardens.

Here's a look at the top five common garden pests, how to identify them, and, more importantly, how to get rid of them.

1. Aphids

Aphids are one of the most dreaded garden pests all around because they target anything in the garden, including indoor and outdoor plants. They seem to show up overnight, out of the blue, and then quickly take over entire plants or crops.

These tiny sap-sucking bugs feed on plant juices which in turn stunts the plant and causes aesthetic damage, and potential death if they aren't dealt with. Aphid damage can cause plant galls, curling of leaves, unformed buds, and deformed flowers, while also transmitting various diseases among plants.

A by-product of their feeding creates a sticky-sweet substance called "honeydew" which in turn causes sooty mold. This attracts ants, which is often why you'll see the two pests working in harmony together, indicating that the plant is already in distress.

How to Identify Aphids

The best way to identify aphids is to watch out for large clumps or groupings of small bugs, especially on the undersides of leaves and emerging flower buds. They're small (about 1/16-inch) but not so small that you can't see them.

There are over 4000 different varieties of aphids, and about 250 that wreak havoc on gardens and plants, so they don't all look exactly the same. They are mostly oval-shaped or circular, soft-bodied insects that vary in color from green, red, brown, black, and white.

Aphid mothers give birth to live baby aphids without the need of a mate all throughout the summer. By the end of the season, males and females mate and create eggs that will overwinter. This amazing ability to reproduce in different ways is one of the reasons they arrive in such large numbers.

Aphids are not without their enemies, and natural predators like ladybugs, aphidlions, and lacewings will all dine on them happily. If you see even one aphid, however, don't wait for nature to take care of the problem, as predators aren't always able to keep up with the reproduction rates of aphids.

How to Deal With Aphids

Take action as soon as you see aphids gathering on your plants, as they can do a tremendous amount of damage if not eradicated quickly.

Thankfully, there are some easy ways to knock them out quickly. A blast of the hose will send them flying off the plant, and even if the fall doesn't kill them, they often won't jump back onto the same plant afterward.

Continue to do this until you don't see any at all, making sure to saturate the soil.

The process may take a few days or even a week, but keep at it, and they'll eventually die off. Since aphids tend to clump on one set of plants, check that they haven't moved onto other plants in the garden.

While insecticidal soap kills them, as well, this tactic is best used for indoor plants since the soap will also kill beneficial insects like bees, butterflies, and moths, including any aphid predators you want to keep around.

2. Japanese Beetles

Japanese beetles were accidentally introduced to North America in the 1900s and originally were only found on islands around Japan, where they were naturally quarantined and kept in check by natural predators.

These invasive species are now considered one of the worst threats to your garden plants and crops, and like aphids, they don't discriminate over what plants to feed on.

The damage is a little different than aphids. Instead, you'll see large, chewed-off areas on foliage that leaves behind a lacy, skeletal look as the veins of the plant are left behind. Plants that have thicker leaves will fare better, but thin foliage can be decimated quickly, and leaves will soon turn brown and fall off the plant.

Other beetles like the Mexican bean beetle will leave behind similar damage, so you still want to identify them properly to know how to deal with them. Japanese beetle grubs will affect lawn roots, causing brown patches and loose grass systems.

How to Identify Japanese Beetles

Japanese beetles have the typical beetle body with six legs and a plump, 1/2-inch big, oval-shaped body. They're winged beetles, and sport two antennae, but their flying habits are slow and clumsy.

The easiest way to identify them is by their greenish-bronze metallic armor that's more green around the body, and bronze on their wings. If you look closely, you can spot tufts of tiny white grouped hairs that complete their interesting uniform.

Japanese beetles feed in smaller groups than aphids, but the damage is just as extensive, even though they only live for about 40 days. They start out as whitish-colored grubs with brown heads that you may find in the soil of your lawn or garden beds.

How to Deal With Japanese Beetles

These bugs are slow and clumsy, so you can easily shake them off of plants into soapy water. They're less active early in the morning and will fall off the plant when disturbed, so check the soil directly underneath, as well.

Insecticidal soap can be used directly on bad infestations, but again, keep in mind that this deterrent also kills beneficial bugs you want to keep around. If using a trap crop to lure them away from other plants, this can help to reduce the need for chemical application.

Treating the grub stage is a great way to reduce the adult population of Japanese beetles. Beneficial nematodes can be purchased and added to lawn and garden soils. It may take a year or two to see results, but it's a good practice to start.

A healthy garden will be able to fare better against any Japanese beetle damage. Work on plant and soil health by adding compost and organic materials, proper watering techniques, and general maintenance around the garden.

3. Squash Bugs

Squash bugs are notorious for causing damage to squash plants like zucchini, pumpkins, gourds, and winter squash, but they will also dine on watermelon, cucumbers, and cantaloupe (the common theme being any plants that grow on vines along the ground).

They prefer young plants and seedlings, and sucking on the plant's juices, causing leaves to yellow and wilt, or turn black. Often the damage is mistaken for bacterial wilt.

Any damage is usually caused early on in the season rather than later, and young plants that haven't fully established yet are the most susceptible to disease and potential death.

How to Identify Squash Bugs

Squash bugs have an interesting shape to them and are easy to identify, although they look and are often mistaken for stink bugs or soldier bugs. They're both flat, with a brownish-gray body, but squash bugs are longer with a semi-hexagonal shaped head and torso.

You may also spot their eggs which will be grouped together on the underside of the plant's leaves. Young nymphs will emerge in early summer, and you'll see groups of them congregating on leaves and young fruit.

Adult squash bugs will feed in groups and like to hide underneath flat objects at night or when it's cold. Place a small piece of flat wood in the garden and lift it up in the early morning as a way to monitor their existence.

How to Deal With Squash Bugs

Although time-consuming, the best way to get rid of them is to handpick them off your plants and drop them into soapy water. If you find eggs clustered under leaves, either scrape them off or spray them with neem oil or insecticidal soap, as the best way to keep infestations down is to destroy them early on.

Unfortunately, once you have squash bugs, it's more of a control game than eradication. Practice good garden hygiene, plant pest-deterring species like nasturtium, and immediately remove any heavily infected foliage and fruit.

Always destroy any infected or damaged material (don't add to compost or leave around the garden), and clean up spent vines at the end of the season to get rid of possible overwintering sites.

Crop rotation can help, as can choosing more squash-bug resistant varieties of squashes. Till the soil before planting again.

Consider covering squash plants and vines until the plant blossoms and is ready for pollination. Once plants are mature, they can usually handle a small amount of squash bug damage.

4. Squash Vine Borers

Another squash pest that you're not likely to see is the squash vine borer. These non-beneficial caterpillars hide out inside plant stems, causing plants to wilt in as if they were thirsty.

If the squash vine borers aren't detected and rid of, the plant eventually dies. Adult moths lay their eggs at the base of the squash plant where the larvae then crawl or bore their way into the stems or vines where they suck on the plant juices from the inside.

This action can also cause swollen looking stems and a material called "frass" which is a sawdusty excrement left behind by the insects burrowing.

How to Identify Vine Borers

You'll find the squash vine borer on any plants in the squash family, like winter and summer squashes, zucchini, gourds, and pumpkins. Unlike the squash bug, they're rarely found inside cucumbers or melons.

Check for small, oval, brown eggs at the base of squash plants in the beginning of the season, since adults lay their eggs very close to the plant, so it's easy for the larvae to find their way into the stem.

You'll find that larvae or caterpillars inside the stem are plump and white with a brown head. They look like lawn grubs or maggots, and grow around one inch.

Adult moths are gray or black with an orangish-red marking on their abdomen, as well as the head and legs. They resemble bees or wasps more than moths or butterflies.

How to Deal With Vine Borers

The best way to get rid of squash vine borers is prevention, and knowing their life cycle. Adults emerge after overwintering in cocoons in late June or early July and then lay eggs. Eggs hatch into larvae about a week or two later.

If you see the eggs, you can pluck them out with a spoon and drop them in soapy water. This is the best preventative method, as adults only lay eggs once a season. If you don't see any eggs but suspect you have borers, look for entry points and slice open the vine in question with a clean utility knife.

Manually remove the borer larvae if you see them, and drop them in soapy water. Remove the damaged part of the vine with garden shears, and then plant it back in the soil. Squash vines will re-root, and may even come back stronger.

Crop rotation and planting times can also help as preventative methods. If squash has been planted early, mature plants may fare better against squash vine borer damage, but squash is also notoriously slow to fruit.

On the flip side, squash can be planted later in the summer after adults are done laying eggs. Try growing long-stemmed and squash vine borer-resistant varieties. Acorn and butternut squash have thicker stems which are naturally more resistant.

green worm with small red horns

5. Tomato Hornworm

The tomato hornworm loves to dine on the leaves of tomatoes, but they will also feast on other nightshade vegetables like peppers, potatoes, and eggplants if tomatoes aren't around (or they've eaten them all).

This caterpillar pest starts to feed on upper leaves first and works its way down, defoliating and decimating the plant in sections, chewing faster as it gets bigger.

Leaves are often first to go, but the hornworm will also destroy fruit, especially in the later stages of its life cycle when it does the most damage.

How to Identify Hornworm

Tomato hornworms are the larvae of the five-spotted hawk moth, which is a large-bodied black, white, and brown patterned hairy moth, with a wingspan of four inches.

Once you see the caterpillars, they're hard to miss. They're much larger than your average caterpillar or insect found in the garden, growing up to four inches long, but because they are a similar green color as tomato leaves, they blend in easily and can go undetected.

Very young caterpillars are whitish, whereas adult caterpillars develop their green color as they grow, as well as white "V" markings along their body and a non-poisonous horn at their backside.

They also leave behind dark green or black droppings as they eat, so keep your eye out for this on the tops and undersides of leaves. If you start to notice a tomato plant that's missing its foliage, you probably have a tomato hornworm problem.

How to Deal With Hornworm

They are slow and bulky, so once found, they can be picked off easily and dropped into soapy water. They have some natural predators to help keep them in check: lady beetles and green lacewings will eat tomato hornworm eggs and small caterpillars.

Wasps will also feed on eggs and young hornworms, and interestingly, a parasitic braconid wasp will lay eggs on the large, adult caterpillars, which ends up killing them.

Since tomato hornworms breed two generations, it's recommended to keep any caterpillars with the wasp eggs on their body if you see them. Once the wasps emerge, they will naturally take out any remaining hornworms populations as they continue to parasitize the infestation.

If tomato hornworms are not kept in check or completely eradicated, enough of them can fully decimate entire plants, especially once they are in the adult caterpillar stage.

Many of the other common garden pests that affect crops and plants that didn't make the list can be dealt with in similar ways as the ones already mentioned.

If you have vine weevils, non-beneficial beetles, or caterpillars like armyworms, cabbage loopers, and cutworms, the method for removal is similar to many of the tactics used for other insects like them.

Once you can identify the pest properly, get to know its life cycle and stop eggs from hatching into larvae. Crop rotation, tilling, and choosing pest-resistant varieties are also good ideas.

Prevention and good garden hygiene will be your first line of attack against the worst garden pests; otherwise, it may be a matter of walking around with a hose or bucket of soapy water and picking off any insects that have overstayed their welcome.