How to Manage Pests
UC Pest Management Guidelines
Scientific Names: Blapstinus spp., Coelus spp., and others
(Reviewed 4/17, updated 4/17)
In this Guideline:
DESCRIPTION OF THE PESTS
Darkling beetles (tenebrionids) are dull bluish black or brown, and about 0.25 inch long. The tips of their antennae are often enlarged, distinguishing them from predaceous ground beetles (carabids), which are beneficial.
These beetles chew off seedlings or feed on foliage. Damage often begins on field edges because this pest typically invades from weeds or adjacent crops. Darkling ground beetles are most active at night.
A shallow ditch filled with water can prevent movement of beetles from adjacent fields.
Organically Acceptable Methods
Use cultural controls in an organically certified crop.
Monitoring and Treatment Decisions
If chewed-off seedlings are found, and darkling ground beetles are present, apply an insecticide. A bait (Permethrin cutworm bait) placed around the edge of the field is usually sufficient.
UC IPM Pest Management Guidelines: Lettuce
Insects and Other Arthropods
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgment for contributions to Insects and Mites:N. C. Toscano, Entomology, UC Riverside