Impact
Lygus bugs, Lygus elisus and Lygus hesperus, are general feeders found on most plants and trees. False chinch bugs, Nysus spp., may mass in large numbers feeding on a wide range of plant hosts.

Seldom do these insects threaten San Luis Valley potatoes. However, isolated problems may prompt consideration of pesticide application.

Description and Symptoms

Lygus bugs

Immature lygus bugs are smooth, shiny-green insects, similar in size to aphids, which move rapidly when disturbed.

Adult lygus bugs are small, brown to green with piercing-sucking mouthparts and a white "V" on the back.

Lygus bugs inject a toxin during feeding. The toxin kills the area fed upon or causes distorted growth. Damage is most severe on field margins.

Highest lygus bug populations develop in alfalfa. Migration into potatoes occurs when alfalfa fields are cut.

False Chinch Bug

The false chinch bug is less than 1/16 inch long, black with white wings and has a triangular black patch in the middle of the outer margins with red legs

Adults become active in early spring, feeding on various weeds.

Populations mass at the top of the plant and wilt or kill the leaves.

A wide variety of weed hosts, such as kochias and mustards, are preferred but migration to potatoes may occur when hosts mature.

Integrated Management

Control populations only when these insects are so abundant as to potentially affect yield. Infestations of false chinch bug, in particular, tend to be patchy in occurrence within a field so spot treatments are most appropriate.

Common insecticides for potatoes can kill natural enemies as well as insect pests. Protect natural enemies that generally keep these pests under control.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.