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Spotted Cucumber Beetle (Diabrotica undecimpunctata)

The spotted cucumber beetle, a member of the leaf beetle family, is a major agricultural pest in North America. The distinct 12 spots on its forewings that is their prominent distinguishable feature, have also resulted in their name. Finnish entomologist Count Carl Gustaf Mannerheim first described it in 1843.

Spotted Cucumber Beetle

Scientific Classification

  • Family: Chrysomelidae
  • Genus: Diabrotica
  • Scientific name: Diabrotica undecimpunctata

Physical Description and Identification

Adult

Size: 6.4mm

Color: Its body is yellowish-green, with twelve characteristic black spots on each of their elytra. The antennae, head, and legs are black.

Other Characteristic Features: Their antenna appears long and slender, measuring 1.6 mm long.

Diabrotica undecimpunctata

Larva

They look like worms because of their slender white bodies and are almost 12mm long. They have a brown capsule for a head that grows in length as the larvae pass through each instar – 0.3 mm for the first instar, 0.4 mm for the second, and 0.6 mm for the final stage.  It has three pairs of long brown legs, alongcol3 a dark plate on the dorsal part of its last segment.

A total of 2 ½ – 3 weeks are required for complete larval development, split as seven days for the first instar, five days for the second, and four days for the third stage.

Spotted Cucumber Beetle Larvae

Pupa

The pupae are white in the beginning, turning yellow as they mature. They are 7.5 mm long and 4.5 mm wide. The cocoon has spines on it as a form of protection, with a pair of stout spines on the tip and smaller ones on the dorsal col3 of their abdomen. This stage lasts for 6-10 days.

Egg

The eggs are yellow and oval-shaped, laid in clusters of 25-40 near the host plant. They are  0.7 mm long and 0.5 mm wide. Generally, it takes  6-9 days to hatch, that may prolong up to 30 days during cold weather condition.

Quick Facts

Other namesSouthern corn rootworm
Lifespan60 days in summer; 200 days in winter
DistributionNorth America, ranging from southern Canada, the continental USA, and parts of the central highlands of Mexico
HabitatAgricultural fields
PredatorsBraconid wasps, soldier beetles, and some nematodes
Seasons activeMarch to July
Host plantsCucurbit plant
Diet of adultsThe leaves of  beans, corn, cotton, cucumbers, soybeans, and squash.
Spotted Cucumber Beetle Damage

Identifying the Damage Caused by Them

Damage caused by these beetles can be identified from holes in the leaves they chewed through and the scars caused by feeding on the host plant, primarily  the stems, crowns, and fruits.

Larvae can cause more significant damage to young plants by attacking their roots, preventing their development.

Did You Know

  • It has three subspecies – D. u. howardi (spotted cucumber beetle), D. u. tenella (western cucumber beetle), and D. u. undecimpunctata (western spotted cucumber beetle).
  • This species can also spread diseases like the mosaic virus and bacterial wilt.
Spotted Cucumber Beetle Picture
Southern Corn Rootworm

Image Source: i.imgur.com, extensionentomology.tamu.edu, pnwhandbooks.org, entnemdept.ufl.edu, 3.bp.blogspot.com, researchgate.net

The spotted cucumber beetle, a member of the leaf beetle family, is a major agricultural pest in North America. The distinct 12 spots on its forewings that is their prominent distinguishable feature, have also resulted in their name. Finnish entomologist Count Carl Gustaf Mannerheim first described it in 1843.

Spotted Cucumber Beetle

Physical Description and Identification

Adult

Size: 6.4mm

Color: Its body is yellowish-green, with twelve characteristic black spots on each of their elytra. The antennae, head, and legs are black.

Other Characteristic Features: Their antenna appears long and slender, measuring 1.6 mm long.

Diabrotica undecimpunctata

Larva

They look like worms because of their slender white bodies and are almost 12mm long. They have a brown capsule for a head that grows in length as the larvae pass through each instar – 0.3 mm for the first instar, 0.4 mm for the second, and 0.6 mm for the final stage.  It has three pairs of long brown legs, alongcol3 a dark plate on the dorsal part of its last segment.

A total of 2 ½ – 3 weeks are required for complete larval development, split as seven days for the first instar, five days for the second, and four days for the third stage.

Spotted Cucumber Beetle Larvae

Pupa

The pupae are white in the beginning, turning yellow as they mature. They are 7.5 mm long and 4.5 mm wide. The cocoon has spines on it as a form of protection, with a pair of stout spines on the tip and smaller ones on the dorsal col3 of their abdomen. This stage lasts for 6-10 days.

Egg

The eggs are yellow and oval-shaped, laid in clusters of 25-40 near the host plant. They are  0.7 mm long and 0.5 mm wide. Generally, it takes  6-9 days to hatch, that may prolong up to 30 days during cold weather condition.

Quick Facts

Other namesSouthern corn rootworm
Lifespan60 days in summer; 200 days in winter
DistributionNorth America, ranging from southern Canada, the continental USA, and parts of the central highlands of Mexico
HabitatAgricultural fields
PredatorsBraconid wasps, soldier beetles, and some nematodes
Seasons activeMarch to July
Host plantsCucurbit plant
Diet of adultsThe leaves of  beans, corn, cotton, cucumbers, soybeans, and squash.
Spotted Cucumber Beetle Damage

Identifying the Damage Caused by Them

Damage caused by these beetles can be identified from holes in the leaves they chewed through and the scars caused by feeding on the host plant, primarily  the stems, crowns, and fruits.

Larvae can cause more significant damage to young plants by attacking their roots, preventing their development.

Did You Know

  • It has three subspecies – D. u. howardi (spotted cucumber beetle), D. u. tenella (western cucumber beetle), and D. u. undecimpunctata (western spotted cucumber beetle).
  • This species can also spread diseases like the mosaic virus and bacterial wilt.
Spotted Cucumber Beetle Picture
Southern Corn Rootworm

Image Source: i.imgur.com, extensionentomology.tamu.edu, pnwhandbooks.org, entnemdept.ufl.edu, 3.bp.blogspot.com, researchgate.net

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