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Past Articles Library | Organic Pest Control | Cucumber Beetle, Spotted

CUCUMBER BEETLE, SPOTTED
(Diabrotica undecimpunctata howardi)

Adult spotted cucumber beetles are one of the most serious pests on cucurbits in many areas, and can eat a wide range of plants. Their larvae, which are known as Southern corn rootworms, typically like to eat corn.

DESCRIPTION

Adults are greenish-yellow, elongated beetles 1/4 inch (6 mm) long, with 11 black spots. The larvae are slender and white, and up to 3/4 inch (2 cm) long, with brown heads and brown patches on first and last segments.

LIFE CYCLE

Adults overwinter under crop debris, and emerge in the spring to lay eggs in the soil close to plants. When eggs hatch, larvae feed in the roots and crowns of plants for 2 to 4 weeks, then pupate. They typically have one or two generations per year in cooler climates, and up to three generations in warmer climates.

PLANTS MOST AFFECTED

Corn, cucumber, peanut, potato and several other plants including many ornamentals.

DAMAGE

Larvae feed on roots, often killing young plants. Older plants are weakened and fall down easily. Adult beetles eat holes in leaves and chew on fruit skin. Larvae and adults transmit cucumber mosaic virus and bacterial wilt diseases.

MEANS OF CONTROL

Prevention:

Plant resistant cucumber, squash, and melon cultivars.

Rotate grden crops with cover crops.

Remove and destroy crop debris to get rid of overwintering sites.

Cover plants with floating row covers.

Heavy mulching can deter cucumber beetles from laying eggs in the ground near plant stems and may hinder feeding by larvae migrating to fruits

Companion plant with oregano, radish, tansy, and nasturtium

Control:

Spot treat with botanical insecticides such as Bon-neem, an insecticidal soap with neem tree oil

Use sticky traps to monitor populations and slow feeding adults

Apply insect parasitic nematodes to soil weekly to control larvae.