The steelblue flea beetle or a close relative is attacking evening primrose in several areas of Illinois. We have had reports of damage in the Morris, Springfield, and Pontiac areas. Although these cities are all in the northern half of the state, this insect may occur at any location. Steelblue flea beetle appears to be a relatively new insect pest in Illinois; it is new to the growers in these areas, and it has not been noticed before in samples submitted to U of I Extension.
The adult insect is about 1/8 inch long and is metallic blue to bronze in color. It is a roundish beetle that jumps when it is disturbed; its hind legs are thickened. These adult beetles eat small holes in foliage, but most of the damage comes from the larvae, which do extensive window feeding. They eat one leaf surface and interior mesophyll, leaving one leaf surface or epidermis intact. This surface is whitish at first but soon dries and turns brown. The larvae grow to about 3/8 inch long and are slender and blackish with short spines all over their bodies.
Information in the literature suggests that the steel-blue flea beetle, Altica torquata, occurs in southern California, Arizona, and New Mexico, where it feeds on desert and evening primrose, as well as grape. Specimens from Illinois that have been sent to me ignore grape but feed heavily on evening primrose, both as larvae and adults. Another species, Altica fuscoaenea, occurs naturally in eastern North America and also feeds on primrose. Finally, there are two other species of Altica in Eurasia that feed on primrose. We will continue trying to determine which species is present here.
Carbaryl (Sevin) provides control of this insect. There is one report of acephate (Orthene) not providing control. We would be interested in hearing if this beetle is found in other locations and the outcomes of control efforts.