Flea Beetles are a frequent nuisance in gardens and responsible for damage that looks like shot holes in the leaves of a host plant. The beetles are usually small, sometimes shiny and jump like fleas when disturbed. The adult stage produces the most damage, although larva can also damage plants.

T here are dozens of species of flea beetles in Colorado, each having a taste for specific plants. Flea beetles can be found on trees, shrubs and flowers, but are most commonly found on vegetables. Adult beetles chew small holes in leaves that resemble fine buck shots. Seedlings and young plants can be seriously damaged or killed by flea beetles. On some flowers and leafy vegetables, damage can be visually unappealing.

Flea beetles over winter as adults in soil and under debris, often around plants infested the previous year. They start becoming active in mid-spring, and are attracted by chemical cues that plants produce. Flea beetles are good fliers and will seek particular plants. They feed for several weeks, and then females lay eggs in soil cracks at the base of the plant. The larvae feed on plant root hairs and small roots. In about a month, the larvae become adult beetles and leave the soil. There can be two to three lifecycles during the summer months.

Some of the flea beetles found in Colorado include the western cabbage flea beetle, which causes the most damage in the state. They prefer host plants in the cabbage family. The apple flea beetle attacks primroses, but will occasionally damage grapes and crabapples. The pale-stripped flea beetle has many favorites, including beans, corn, lettuce, squash, sunflowers, potatoes and weeds. The potato flea beetle prefers plants in the nightshade family like tomatoes and potatoes.
The tuber flea beetle inflicts the most damage in the larval stage. The larvae will damage the skin of potato tubers. They burrow into the tuber and create small tunnels in the potato skin that creates surface scabs on the potato. The sumac flea beetle and the willow flea beetle both have larvae that feed on the leaves of their host plants.

Seedlings and young plants are at the highest risk of injury from flea beetles, but there are tactics to protect them until establishment. Floating row covers can be used to keep the beetles away from the young plants. Remove the row covers when the plants mature and can withstand beetle injury. Using a thick layer of mulch around the base of plants can minimize the larva in the soil and limit subsequent beetle generations.

Sometimes another plant crop can be used to lure flea beetles away from the main crop. An example is planting radishes to draw western cabbage flea beetles away from plants such as cabbage, broccoli and Brussels sprouts. The radishes could then be harvested or disposed of once the main crop was protected.

Diatomaceous earth, applied as a powder to plant leaf surface can be a useful repellant. Some Neem insecticides and horticultural oils have also been proven to have an effect on flea beetles. Chemical controls include products containing permethrin and carbaryl (Sevin). These chemicals work for about a week and have to be applied several times to protect young plants. Make sure that the pesticide is registered for use on the crop. Read and follow all label instructions before using any chemical on food crops.

Armed with the knowledge of the life cycle and methods to control flea beetles, damage can be greatly reduced. Flea beetles no longer need to be the bane of the home gardener.

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

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This page updated:  November 1, 2006