Flea Beetles

(Epitrix spp., Phyllotreta spp.)

These are tiny-about one-sixteenth of an inch–shiny black beetles with enlarged hind legs that enable them to jump like fleas. Flea beetles commonly attack the foliage of newly planted vegetable seedlings, especially tomatoes, potatoes, peppers, eggplants, cabbage and broccoli, turnips, radishes, and com. Serious damage is usually limited to plants with fewer than six leaves, although eggplants can be attacked up to the fruiting stage.

BIOLOGY: There are numerous flea beetle species (illustrated: Epitrix cucumeris), but as a group they overwinter in soil or in crap debris. Adults emerge in the spring and seek out host plants, which include weeds as well as crops. Feeding females lay eggs in soil cracks near the base of the plants. The eggs hatch in about a week, and the tiny white wormlike larvae feed on small roots and root hairs, causing little injury. After feeding for two to four weeks, the larvae pupate in the soil. Seven to ten days later they emerge as adults. One to four generations per year may occur.

SYMPTOMS: Flea beetles create a series of small holes or pits gouged into the surface of leaves. The edges of the holes eventually turn brawn.

CONTROLS: Removing or burying crop residues will destroy overwintering sites. Because seedlings and young plants are most at risk, holding seedlings indoors until they are more mature will reduce damage. Alternatively, newly set-out transplants can be covered with floating row covers to screen them. Delayed planting will also encourage emerging flea beetles to congregate on alternative host weeds. A trap crap can also be sown. Such a planting might be Chinese cabbage, red Russian kale, glossy leaf collards, mustard, turnip, or a number of other attractive plants. Seedlings already under attack can be treated with permethrin, bifenthrin, spinosad, rotenone, or carbaryl. Diatomaceous earth, capsaicin, and horticultural oil offer some repellent benefit. Reapplication will be necessary to protect the new growth from subsequent attack by these highly mobile pests. Finally, entomophagic nematodes (HetemrhaMitis, Steinernema) will control flea beetle larvae.

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