Corn Flea Beetle
Chaetocnema pulicaria Melsheimer, Chrysomelidae, COLEOPTERA


DESCRIPTION

Adult - This oval, black beetle is tinged with bronze or bluish-green, has yellow markings on its legs, and is 1.3 to 2.5 mm long. The basal segment of each antenna is orange.

Egg - Each white egg is about 0.35 mm long and pointed at one end. It gradually darkens before hatching.

Larva - The white, slender, cylindrical grub has a brown head and tiny legs. It may be 3.2 to 8.5 mm long when full grown.

Pupa - The white, soft-bodied pupa resembles the adult in size and somewhat in shape and gradually darkens as it matures.


BIOLOGY

Distribution - The corn flea beetle occurs in most areas east of the Rocky Mountains. It infests corn all across North Carolina but appears to create more concern in the Piedmont counties.

Host Plants - Although the corn flea beetle is a general feeder, most hosts are grasses. However, sugar beets are periodically infested in other states.

Damage - Corn flea beetles attack foliage, leaving small round holes and bleached out spots or stripes; the larvae feed on the roots of grasses. However, the direct loss caused by these injuries is relatively insignificant. The overwintering beetles which carry bacterial wilt of corn (Stewart's disease) are primarily responsible for any economic damage. These beetles are usually most troublesome after a mild winter followed by a cold spring. Under such conditions, high numbers of beetles survive the winter and attack the slowly growing corn over a prolonged period. Growth is retarded and leaves may wilt. Early maturing varieties in the middle and southern states are most seriously affected. Color plate.

Life History - Adults generally overwinter in litter and trash around fields. Mortality tends to be high during harsh winters. In early spring, the beetles move to weeds and then to corn seedlings. Eggs are scattered on the soil beneath host plants. In about 10 days, the larvae emerge and begin feeding on and tunneling in underground stems, roots, or tubers. They feed for 3 to 4 weeks and develop through three instars before pupating in the soil. In 7 to 10 days, a new generation of adults emerges. Three or more generations are completed each year.


CONTROL

Damaging corn flea beetle infestations can be prevented by plowing under crop residue and maintaining good weed control to eliminate overwintering sites. The use of wilt resistant hybrids also lessens the chances of excessive loss due to bacterial wilt. For specific control information, consult the current North Carolina Agricultural Chemicals Manual.