Cucumber Beetles
Pest · Commonly affects: Cucumbers, Zucchini and summer squash, Winter squash and pumpkins, Cantaloupe and other melons, Watermelon, Gourds
Cucumber beetles are small yellow-and-black beetles that attack cucumbers, squash, and other cucurbits across the United States, appearing in two common forms: the striped cucumber beetle and the spotted cucumber beetle. Gardeners watch for them closely because, beyond chewing on leaves and flowers, they spread bacterial wilt and mosaic viruses that can kill a plant outright.
How to identify it
Adults are about a quarter inch long with a yellow to greenish body; the striped kind has three black stripes running the length of its wing covers, while the spotted kind carries eleven or twelve black spots and resembles a miscolored ladybug. The slender, pale larvae feed underground on roots and are rarely seen. Look for the adults on the undersides of leaves and tucked inside blossoms, where they quickly scatter and drop to the ground when you disturb them.
Damage
Adults chew ragged holes in leaves, scar stems, and feed on flowers and young fruit, while the larvae gnaw on roots and can girdle seedlings at the soil line. The bigger danger is disease: as they feed they transmit the bacterium responsible for bacterial wilt and can carry cucumber mosaic virus, so even a few beetles can lead to plants that suddenly yellow, wilt, and collapse.
Prevention
Rotate cucurbits to a new part of the garden each year and clear away old vines and plant debris in fall, since the beetles overwinter in sheltered spots near previous crops. Choose varieties described as wilt-tolerant or resistant when available, and give plants generous spacing with steady watering and healthy soil so they grow vigorously enough to outpace early feeding. Delaying planting slightly, or setting out sturdy transplants, helps seedlings move quickly through their most vulnerable stage.
How to manage it
Cover young plants with floating row covers from planting until flowering to keep beetles off, then lift the covers so bees can reach the blossoms or hand-pollinate the flowers yourself. Handpick adults in the cool of early morning when they are sluggish, dropping them into soapy water, and hang yellow sticky traps to catch more. Encourage natural enemies such as tachinid flies, braconid wasps, soldier beetles, and ground beetles, and promptly pull and remove any plant that begins to wilt so the disease does not spread to healthy neighbors.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.