Sweetpotato Flea Beetle
Chaetocnema confinis Crotch, Chrysomelidae, COLEOPTERA


DESCRIPTION

Adult - The tiny oval beetle is black with a bronze tinge and about 1.6 mm long. It has reddish-yellow legs and deeply ridged wing covers.

Egg - Each white, oblong-oval egg is about 0.2 mm long.

Larva - The slender, white, cylindrical larva has three pairs of legs near its head. It is about 4.8 mm long when fully grown. This larva has no dark spot or fleshy tubercle on its tail-end like cucumber beetle or palestriped flea beetle larvae.

Pupae - The pupa is white at first but gradually darkens and is approximately the same size and shape as the adult.


BIOLOGY

Distribution - The sweetpotato flea beetle occurs in practically all areas of this country where sweet potatoes are grown.

Host Plants - Sweet potato, corn, small grains, bindweed, raspberry, and sugar beet are the main food plants of this pest.

Damage - Adult flea beetles feed on foliage leaving narrow channels or grooves in the upper surfaces of leaves. These injured areas turn brown and die. Larvae live underground and feed on roots. Shallow winding tunnels etched into root surfaces indicate an infestation of flea beetle larvae. These tunnels eventually darken and split open leaving shallow scars. This type of damage usually is restricted to fibrous roots, but, during heavy infestations, larvae may injure the fleshy marketable portion of roots in the same manner as fibrous roots.

Life History - Sweetpotato flea beetles overwinter as adults under logs and leaves, along fence rows, and at the edges of wooded areas. They resume activity in spring and begin to deposit eggs in soil near host plants. A few days later eggs hatch. Newly emerged grubs feed for about 3 weeks before pupating in the soil. During summer, the entire life cycle is often completed in 30 days. Several generations per year are possible. From June onward, however, most eggs are deposited near bindweed, and flea beetle populations on sweet potato decline.


CONTROL

Cultural practices are instrumental in preventing flea beetle infestations. Controlling weeds along fence rows and plowing under crop debris destroy overwintering and egg-laying sites. However, the use of resistant varieties such as Jewel or Centennial is the most effective means of preventing sweetpotato flea beetle injury.

In fields with a history of flea beetle infestation, chemical control may be justified. Preplant, soil-applied insecticides are available for this purpose. For recommended chemicals and rates, consult the current North Carolina Agricultural Chemicals Manual.

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