Grow It Eat It: Maryland's Food Gardening Network

Top Vegetable Pests - Cucumber Beetles: Spotted or Striped

Spotted cucumber beetle (Southern corn root worm) Diabrotica undecimpunctata howardi & Striped cucumber beetle Acalymma vittata


Adult	Damage symptoms	Control: Floating row cover

Appearance	Host Plants	Monitoring
Life Cycle/Habits	Signs/Symptoms	Prevention/Control

Appearance Eggs: clusters of yellow to orange ovals on or just under coarse, cracked soil. Larvae: both species are white (Striped more yellowish) 1/2" long with dark heads.
Adults: up to 1/4" long with black head. Spotted beetle is yellow-green with 12 black spots. Striped beetle is yellow with three black longitudinal stripes.

Life Cycle/Habits Overwinter as adults in plant debris and nearby wooded areas (striped also in soil.) In spring, spotted cucumber beetle prefers wet, coarse soil to deposit eggs. Striped cucumber beetle deposits eggs around plant base, on vine, or just below soil surface. Spotted cucumber beetle larvae feed on roots, stem base, or fruit surface (thus the name "rindworm"). Striped cucumber beetle larvae feed mostly on roots and stems. After pupating in soil, adults feed on seedlings, petals, leaves, and fruit-- especially fruit undersides where it is shady and cooler. (Plants are generally less prone to damage after fruit set.) 4-6 weeks for each lifecycle. One to three generations per growing season.

Host Plants Spotted: Cucurbits (i.e. cucumber, squash, pumpkin, muskmelon) legumes, tomato, ornamentals, and fruits plus many other weeds and cultivated plants.
Striped: primarily cucumbers & other cucurbits, but in shoulder seasons many other crops such as apple, pear, green beans, okra, eggplant, potato, plus tree and shrub blossoms. These pests are attracted to plants pigweed and various other amaranth species.

Signs/Symptoms Larvae eat roots and burrow in young plant stems, causing wilt or death. Adults eat seedlings; chew holes in leaves, flowers and fruit. Gouge and rasp fruit, especially smooth melons and fruit undersides contacting soil. Transmit devastating cucurbit bacterial wilt, which causes sudden wilt and death, mainly of cucumber and muskmelon- but also summer squash. Spotted cucumber beetle (Southern corn rootworm) eats roots of bean, corn as well as curcubits. Spreads mosaic virus and muskmelon necrotic spot virus. Striped cucumber beetle also spreads Fusarium wilt and squash mosaic virus.

Monitoring Inspect dying seedlings for larvae. Inspect chewed leaves, petals, and fruits for adults, especially leaf and fruit undersides touching soil, in flowers and at stem bases. If cucumber plant wilts suddenly, check for bacterial wilt by cutting wilted stems. Touch the cut ends together and pull apart slowly. Sap will string out in fine strands.

Prevention/Control

Prevention and early control are essential. In fall, remove garden debris (overwintering sites). In fall or spring it can be helpful to lightly till soil to kill eggs and larvae.

Use floating row covers over susceptible plants until they bloom. Remove the row cover to allow insects in to pollinate the flowers.

Spray with pyrethrum, neem, or spinosad products.

Plant "County Fair", a pickling cucumber cultivar that has natural resistance to bacterial wilt.

Avoid this pest by planting susceptible crops around June 15, after overwintering adults have emerged.

Handpicking is difficult because these pests are fast and drop when disturbed.

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For more information, contact Jon Traunfeld

Last updated: 08/10/2010

Appearance	Eggs: clusters of yellow to orange ovals on or just under coarse, cracked soil. Larvae: both species are white (Striped more yellowish) 1/2" long with dark heads. Adults: up to 1/4" long with black head. Spotted beetle is yellow-green with 12 black spots. Striped beetle is yellow with three black longitudinal stripes.
Life Cycle/Habits	Overwinter as adults in plant debris and nearby wooded areas (striped also in soil.) In spring, spotted cucumber beetle prefers wet, coarse soil to deposit eggs. Striped cucumber beetle deposits eggs around plant base, on vine, or just below soil surface. Spotted cucumber beetle larvae feed on roots, stem base, or fruit surface (thus the name "rindworm"). Striped cucumber beetle larvae feed mostly on roots and stems. After pupating in soil, adults feed on seedlings, petals, leaves, and fruit-- especially fruit undersides where it is shady and cooler. (Plants are generally less prone to damage after fruit set.) 4-6 weeks for each lifecycle. One to three generations per growing season.
Host Plants	Spotted: Cucurbits (i.e. cucumber, squash, pumpkin, muskmelon) legumes, tomato, ornamentals, and fruits plus many other weeds and cultivated plants. Striped: primarily cucumbers & other cucurbits, but in shoulder seasons many other crops such as apple, pear, green beans, okra, eggplant, potato, plus tree and shrub blossoms. These pests are attracted to plants pigweed and various other amaranth species.
Signs/Symptoms	Larvae eat roots and burrow in young plant stems, causing wilt or death. Adults eat seedlings; chew holes in leaves, flowers and fruit. Gouge and rasp fruit, especially smooth melons and fruit undersides contacting soil. Transmit devastating cucurbit bacterial wilt, which causes sudden wilt and death, mainly of cucumber and muskmelon- but also summer squash. Spotted cucumber beetle (Southern corn rootworm) eats roots of bean, corn as well as curcubits. Spreads mosaic virus and muskmelon necrotic spot virus. Striped cucumber beetle also spreads Fusarium wilt and squash mosaic virus.
Monitoring	Inspect dying seedlings for larvae. Inspect chewed leaves, petals, and fruits for adults, especially leaf and fruit undersides touching soil, in flowers and at stem bases. If cucumber plant wilts suddenly, check for bacterial wilt by cutting wilted stems. Touch the cut ends together and pull apart slowly. Sap will string out in fine strands.
Prevention/Control	Prevention and early control are essential. In fall, remove garden debris (overwintering sites). In fall or spring it can be helpful to lightly till soil to kill eggs and larvae. Use floating row covers over susceptible plants until they bloom. Remove the row cover to allow insects in to pollinate the flowers. Spray with pyrethrum, neem, or spinosad products. Plant "County Fair", a pickling cucumber cultivar that has natural resistance to bacterial wilt. Avoid this pest by planting susceptible crops around June 15, after overwintering adults have emerged. Handpicking is difficult because these pests are fast and drop when disturbed.