Spotted Cucumber Beetle

Common: Southern Corn Root Worm, Spotted Cucumber Beetle,

Scientific: Diabrotica undecimpunctata

Crop Hosts: Corn is the primary economic crop but it has also been found on a very large number of plants.

Identification and Life Cycle: In contrast to the other two rootworms the Northern or Western, this insect overwinters as an adult. The head is black and it has 12 conspicuous black spots on the wing. The adults deposits between 200 to 1200 eggs around the base of the corn plant. The young larvae hatch, bore into the roots and become full grown by July when they pupate in the soil. Generally, there are two generations. The adults can live for more than 300 days.

Geographical Distribution: It is widely distributed throughout the United States, but is particularly destructive in the southern part of its range.

Damage and Treatment: In addition to injury to the roots the lower stalk will usually be bored through by the grubs. The result is a low vigor corn plant that can be blown over by winds. Rotation of crops is of little value in its control.

Treatment should be made when insect populations and/or damage levels reach economic thresholds. Refer to local University Extension Pest Management Guidelines for specific state thresholds.