How to Manage Pests
Pests in Gardens and Landscapes
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.
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.
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.
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.