How to Manage Pests

Darkling beetles

Darkling beetles are dull bluish black or brown. They never have color patterns on the back. In most species, the segments at the tip of the antenna are slightly larger than segments at the base. Darkling beetles are found throughout California.

Identification

Darkling beetles can be confused with predaceous ground beetles, but the latter are usually shiny, and the tip segments of their antennae are rarely as enlarged as those of darkling beetles. Plant-feeding darkling beetles can be distinguished from predaceous ground beetles by examining where their hind legs meet their abdomen. The enlarged lobe on the first segment of the back legs (trochanter) of predaceous ground beetles is very characteristic. Also the hind leg coxae completely divide or cover at least the first abdominal segment; coxae of darkling beetles are not enlarged. Some predaceous ground beetles have prominent patterns of lighter colors; they feed mostly on caterpillars and other insects.

Damage

Darkling beetles chew off seedlings or feed on foliage of several different vegetable crops. Feeding in some fruit crops, such as figs, may also occur. Beetles are most active at night but occasionally run on the ground in the daytime. They often hide under clods or debris during the hot parts of the day.

Solutions

To help reduce population levels, remove or hasten the breakdown of organic matter to reduce the available host material for larvae. Be sure the garden and borders are weed and debris-free before you plant.

Darkling beetle adult