Flea beetles and flea beetle rootworms (extended information)

Chaetocnema pulicaria and Chaetocnema spp.

Description and life cycle

The small (1mm - 2mm) shiny, black beetles deposit their eggs in soil, where the tiny rootworms develop into white, delicate pupae. The adults can fly and typically have swollen hind legs that are well adapted for jumping.

Mechanism of damage

On recently emerged seedlings, the main symptom of attack is white, thin, elongated lesions (injured areas) along the upper leaf surface, which is the result of scratching between the leaf veins by the beetles. They may continue to cause this type of damage as long as there is green tissue in maturing plants and will occasionally perforate the leaf as well. The worms feed on the roots, sometimes causing maize plants to lodge.

Geographic distribution

These pests can be found worldwide. In temperature climates the beetles are important vectors of Stewart's wilt bacteria. This disease is of no economic importance in the tropics, however.