Flea Beetles

Flea beetle adults are 0.12 inch (3 mm), shiny beetles with enlarged hind legs that allow them to jump like fleas. The palestriped flea beetle has a broad white stripe down each brown wing. The potato flea beetle is a uniform black color.

The larvae live in the soil, are slender, whitish, and about 0.25 inch (6 mm) long when mature.

Adult flea beetles do most of their damage by feeding on the undersides of leaves, leaving small pits or irregularly shaped holes on the leaves. Large populations can kill or stunt seedlings. Older plants rarely suffer economic damage although their older leaves may be damaged.

In the Imperial and San Joaquin Valleys, larvae are known to cause serious damage by feeding on the roots. Wounds on the surface of the taproot often follow a straight or curved line down on side of the root. This damage is easily confused with cavity spot symptoms. Cavity spot lesions are elliptical and more sunken, are more randomly scattered on the root surface, and tend to be more concentrated on the upper third of the root.

Remove weeds along field margins and deeply disk plant residue in infested fields after harvest.

Use cultural controls in a certified organic crop.

Check newly emerged seedlings twice weekly for flea beetle damage until plants are well established. Relatively low populations can cause economic damage when plants are in the cotyledon or first-leaf stages. Apply insecticides if you find several damaged rows; spot treatment of outside rows or borders may be sufficient. Baits are not effective.

Once plants have several true leaves, they can tolerate several beetles per plant without damage. Older plants are even more tolerant. Insecticide treatment should rarely be required, but if it is, one application should suffice. However, chemical treatment may disrupt biological control of aphids and whiteflies. Encourage buildup of beneficial insects by avoiding the use of nonselective pesticides and by protecting their habitat.