Thanks to their prolific nature, cucumbers often get a reputation for being an easy-to-grow plant. Healthy plants can quickly sprawl across your garden and provide you with handfuls of crunchy cucumbers. But when pests attack, the plants can quickly become diseased or experience a decrease in productivity.

First, pay attention to plant health. Stressed plants are more susceptible to attack, so make sure the plants receive the water, nutrients, and light they need. Provide these thirsty plants with plenty of water, plant them in a location with full sun, and fertilize well but not too much.

Another way to keep cucumber pests in check is to encourage the presence of natural predators. Insects like ladybugs, green lacewings, hoverflies, and parasitic wasps feed on pests and help keep their populations low.

One way to encourage the presence of these good bugs is by avoiding broad-spectrum insecticides. If you choose to spray for pests, choose a targeted product and spray in the morning or evening when insects are the least active.

Planting an array of flowering plants will also help keep predators around, since many of these critters feed on pollen and nectar. Try planting small flowers like sweet alyssum and dill in with your veggies to provide food for hoverflies and green lacewings.

Common Cucumber Pests

Even if you do your best to keep your cucumbers healthy and attract natural predators, it’s still possible that unwanted insects will appear. Here are some of the most common cucumber pests to watch out for.

Cucumber Beetles

These insects can cause ragged leaves and stems, misshapen fruits, and can spread bacterial diseases.

An unwelcome sight to cucumber growers everywhere, these little yellow beetles can cause serious damage. Their chewing can lead to ragged leaves and stems, as well as misshapen fruit. They can also spread diseases like the dreaded bacterial wilt.

There are multiple types of cucumber beetles, including striped and spotted varieties, but all of these insects are around a quarter of an inch long. The striped cucumber beetle (Acalymma vittatum) has black and yellow striped wings, a yellow-orange thorax, and a black head. The spotted cucumber beetle (Diabrotica undecimpunctata) has yellow wings with black spots, a yellow thorax, and a black head.

The adults overwinter in plant debris in warm climates and become active once the weather warms. Although they may not survive the winter in more northern climates, they migrate to these areas in the summer. Once they arrive, they begin feeding on plants.

Eventually, the adults lay their eggs near the base of cucurbit plants. The eggs hatch in a few weeks, and the small worm-like larvae then feed on plant roots. They emerge as a new generation of adults about a month later.

Signs of Damage

The insects chew on leaves, stems, and fruits of the plant.

The adults chew on cucumber leaves, stems, and fruits. Since the beetles are tiny, they may only eat through the top of the leaves rather than the entire leaf.

Although a few of the pests won’t cause a noticeable impact, large infestations can lead to ragged leaves and/or damaged fruits. However, the pests also transmit bacterial wilt, a disease that can cause plants to suddenly wilt and die. This disease transmission means it’s wise to protect your plants from even a few beetles.

Prevention

Protect the plants by covering them with netting or applying beneficial predatory nematodes to the soil.

The best way to protect your plants from these pests is to physically exclude them from your plants. Covering your cucumbers with row cover or insect netting after planting will do the trick. However, you must remove these covers when the flowers appear, unless you plant a parthenocarpic variety that doesn’t require pollination to set fruit. ‘Telegraph Improved’ is one type of parthenocarpic cucumber.

You can also help limit cucumber beetle populations by applying beneficial predatory nematodes to the soil. These nematodes feed on and kill beetle larvae, but they won’t impact adults that overwinter and/or fly in from other areas.

Control

Control the population by squishing them, using pesticides, or disposing of blight-affected foliage.

If you spot a cucumber beetle, there are probably more on the way. You can attempt to squish the adult beetles by hand, but their tendency to quickly fly away makes this tricky. Another option is to spray the beetles with an organic insecticide, like spinosad. Only spray your plants when there are two or more beetles per plant.

If you notice bacterial wilt in one of your plants, pull and dispose of it ASAP. This will help prevent the disease from spreading to other plants.

Aphids

Aphids can quickly multiply and colonize the plant.

These tiny, soft-bodied insects might not look like major pests, but they can quickly multiply and colonize a cucumber plant.

Aphids come in shades of green, red, gray, black, and brown, but the green peach aphid (Myzus persicae) is the aphid that’s most commonly found on cucumbers. These tiny pests often appear on the underside of cucumber plant leaves or on young, growing tips.

Aphids are less than a quarter of an inch long, so you may need to look closely to spot them. Regularly checking the underside of plant leaves is a good way to catch them early.

Signs of Damage

Infested plants can appear spotted or distorted, and can become stunted and weak.

Aphids feed on plants by piercing their leaves and sucking out the sap. Plants with early infestations rarely show signs of damage, but the leaves may eventually appear spotted or distorted. If the aphids are left untreated, plants can become stunted and weak.

Aphids also release a sticky substance known as honeydew as they feed. This sugary liquid can coat the leaves and lead to the presence of ants and/or black sooty mold.

Prevention

A severe infestation can be prevented by planting small flowers that attract beneficial predators like hoverflies.

Aphids often occur in gardens, even if you don’t see them. Fortunately, natural predators feed on the pests and keep them from getting out of control. Therefore, encouraging these predators is one way to prevent aphids from becoming a big problem. Planting small flowers like yarrow, fennel, and sweet alyssum can help attract beneficials like hoverflies and parasitic wasps.

Properly fertilizing your cucumbers is another way to limit major aphid infestations. Avoid over applying nitrogen, since aphids reproduce more rapidly when plants have high nitrogen levels.

Control

Aphids can be controlled by spraying them with neem oil or insecticidal soap.

If you see aphids on your cucumber plants, you can try to spray them off the plants with a blast of water. If this doesn’t work, spray them with neem oil or insecticidal soap while ensuring that you make contact with the pests. Spraying in the early morning or evening is best.

Pickleworms

The insect feeds on flower buds and fruits of the plants.

Although pickleworms (Diaphania nitidalis) are often found on summer squash and zucchini, they can also become pests of cucumber plants. The worms are the larvae of a brown and yellow nocturnal moth that overwinters in warm climates. The moths eventually fly into northern areas where they lay their eggs near host plants.

When the eggs hatch, the small, light yellow larvae feed on cucumber flower buds and fruits, as well as other cucurbits like squash and melons. The larvae molt a few times before they pupate and turn into adults.

Signs of Damage

Holes in the fruit and a hollow cavity are common signs of damage caused by the worms.

The most obvious sign of pickleworm damage is small holes in cucumbers, with a jelly-like substance around the outside of the holes. If you cut open the cucumber, you’ll see the larvae and notice a hollow cavity where it’s dined on the fruit. You may also be able to spot the pickleworms eating flowers or buds.

Prevention

Prevent any infestations by covering the plants with insect netting, destroying infected plant matter, and planting trap crops.

Since pickleworms arrive in most climates later in mid to late summer, you can avoid them by planting early-maturing varieties. Covering your plants with row cover or insect netting will also protect them from the moths and prevent worm damage.

If you live in a warmer region, say zone eight and below, the pickleworms may be able to overwinter in your area. Destroying plant material and debris can help kill the larvae and prevent worms from growing the next season.

You can also attempt to prevent infection via trap cropping. Pickleworms prefer summer squash over cucumbers, so planting a squash plant a few weeks earlier than your cucumbers will attract the worms to the squash. Once they take hold of the squash, you can destroy them by removing the infected fruits.

Control

If there are larvae in the flowers, spray the plants with BT to kill the worms.

Since pickleworms often enter into cucumbers, it’s too late to treat them by the time you notice them. If you notice the larvae in the flowers, you can spray your plants with Bt to kill the worms.