1 June 2006
Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580 fax: 434.872.4578
If you grow vegetables you may find small dark colored beetles chewing on your foliage this time of year. There is group of small black or brown vegetable munching beetles commonly called flea beetles for their tendency to hop away when disturbed. There are many species of flea beetles in the Order Coleoptera and Family Chrysomelidae and they are usually given common names that correspond to the plants they feed on such as the following.
- Eggplant flea beetle, Epitrix fuscula (Crotch)
- Potato flea beetle, Epitrix cucumeris (Harris)
- Tobacco flea beetle, Epitrix hirtipennis (Melsheimer)
- Striped flea beetle, Phyllotreta striolata (Fab.)
- Sweet potato flea beetle, Chaetocnema confinis (Crotch)
- Corn flea beetle, Chaetocnema pulicaria (Melsheimer)
Many species of flea beetles attack vegetables and other plants in Virginia. These plants include watermelon, pumpkins, peas, beans, tomato, pepper, cabbage and related crops, eggplant, beet, spinach, turnip, mustard, and radish. Potato, tobacco and corn flea beetles are most common and have wide host ranges. The striped flea beetle is limited to plants of the cabbage family, the eggplant flea beetle to eggplant, and the sweet potato flea beetle to sweet potatoes, corn, and plants of the morning glory family. Adults attack the foliage and chew small, round holes giving a 'shot-hole' appearance. Larvae feed on the roots of host plants.
Adults generally overwinter in debris around fields of host plants, and move to weeds and plant beds in early spring and later to transplanted vegetables and garden plants. They are most destructive to young plants. They lay eggs scattered on the soil beneath host plants. Eggs hatch in about 10 days, and the slender, white larvae feed on and tunnel in underground stems, roots and/or tubers for 3 to 4 weeks. There are usually 3 instars or larval stages. Pupae usually remain in the soil for 7 to 10 days until adults emerge and the cycle is completed. There are 3 or more generations per year.
Adult - The potato and eggplant flea beetles are about 1/10 inch long and nearly uniform black. The equally small tobacco flea beetle is yellowish-brown with a dark band across the wings. The sweet potato and corn flea beetles, about the same size, have a bronzy reflection. The striped flea beetle is about 1/2 inch long with a crooked, yellowish strip on each wing cover. All have thickened hind legs which enable them to jump.
Larva - Larvae are mostly whitish, slender, delicate, cylindrical worms from 1/8 to 1/3 inch long when fully grown with minute legs and brownish heads. Larvae are seldom seen by gardeners.
Some flea beetles are general feeders, but most attack only closely related plants. For example, the potato and tobacco flea beetles attack potato, tobacco, tomato, pepper, horse nettle and related weeds. The eggplant flea beetle, striped flea beetle (cabbage family only), and the sweet potato flea beetle are fairly specific in the host plants. The corn flea beetle is a general feeder.
Adult flea beetles chew very small, rounded holes in leaves, causing a short-hole appearance. These holes provide an entrance for plant diseases. The potato flea beetle spreads early blight. The corn flea beetle vectors bacterial wilt of corn. Larvae feed on roots, and with the sweet potato and potato flea beetles, heavy losses to edible roots or tubers may result.
Keeping fields free of weeds is important. Late planting also favors growth of host plants over establishment of flea beetles. Destroy plant residues and remove from the area to prevent beetle buildup. Debris around plant beds where beetles hibernate should be destroyed and beds covered.
A number of insecticides are available to control adult flea beetles. Be careful not to treat plants when bees are pollinating and always read the label before applying to protect yourself and those around you. For organic control, dust with diatomaceous earth or use rotenone for serious infestations.
Identification and Diagnosis
As always, if you have an insect you want identified or a plant problem you want solved you can bring a sample to your local Extension office and we will be glad to help you. If you are not sure which part of a plant to bring or how to package your insects for travel, please give us a call before you come. It is best to receive whole, uncrushed insect specimens for identification.
For more information about these and other landscape gardening topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.
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