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Spotted Cucumber Beetle

Diabrotica undecimpunctata[3]

The spotted cucumber beetle, also called the southern corn rootworm, is a yellow-green beetle with 12 black spots that feeds on cucurbits and many other plants.[1][2]

Group
Insect
Order
Coleoptera
Family
Chrysomelidae
US records
43 states
Sources
3 cited
Updated
2026-10-16
Spotted cucumber beetle, yellow-green with black spots, on a flower
Spotted cucumber beetle, yellow-green with black spots, on a flower. (c) Sam Kieschnick, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • Adults are about 1/4 inch long, yellow-green with 12 black spots on the wing covers and a black head, legs and antennae.[1][2]
  • Larvae are slender, white, worm-like, about 1/2 inch long, with a brown head and a dark plate on the last segment.[1][2]

Look-alikes

Look-alikeHow to tell them apart
Striped cucumber beetleAnother cucurbit beetle; in Florida it is less common than the spotted cucumber beetle.[1]
Banded cucumber beetleA related Diabrotica beetle more common in southern Florida.[1]

Where it lives

A native beetle found across the United States from Mexico to Canada, most abundant and destructive in the South.[1]

US map: public records from 43 states since 1990 (GBIF).

Biology and life cycle

Unmated adults overwinter under leaves and debris near woods and buildings and become active above about 50 degrees F in spring.[1][2]

Females lay yellow eggs in clusters in the soil near hosts such as grasses, cucurbits and legumes; larvae feed on roots for two to four weeks.[1][2]

Damage and signs

  • Adults chew roots, seedlings, flowers and leaves; feeding on young cucurbits can cause wilting and lower yields.[1][2]
  • They spread the bacterium that causes bacterial wilt of cucurbits, a serious concern in the central and eastern United States.[1]
  • Larvae bore into roots and stem bases and can badly damage small plants.[1]

Health risk

None to people or pets.[1][2]

Control

Prevention

Use mulches and drip irrigation, avoid planting cucurbits next to beans, corn or grassy weeds, and plant attractive cucurbit trap crops two weeks before the main crop.[1][2]

Keep them out

Protect small plants with row covers, screens or cones.[1]

Pesticides

Organic options include kaolin clay, pyrethrum and spinosad; rotate modes of action and combine sprays with cultural and biological controls.[1]

Common questions

What are the yellow beetles with black spots on my squash?
Likely spotted cucumber beetles.[1][2]
Why did my cucumber vines wilt suddenly?
Cucumber beetles can spread bacterial wilt as they feed.[1]

Sources

  1. University of Florida IFAS Extension (EDIS, Featured Creatures), “Spotted Cucumber Beetle, Diabrotica undecimpunctata howardi (EENY-572).” ask.ifas.ufl.edu/publication/IN1008 (accessed 2026-10-16)
  2. Utah State University Extension (Integrated Pest Management), “Spotted Cucumber Beetle (hemp pest fact sheet).” extension.usu.edu/planthealth/ipm/notes_ag/hemp-spotted-cucumber-beetle.php (accessed 2026-10-16)
  3. iNaturalist, “Diabrotica undecimpunctata taxon page (order and family).” www.inaturalist.org/taxa/55487 (accessed 2026-10-06)

Updated 2026-10-16. Built from sourced records. Spot an error? Tell us.