How to Manage Pests

Pests in Gardens and Landscapes

Viral diseases

Virus diseases can be a very effective natural control of caterpillars. Caterpillars, including cabbageworms, loopers, and armyworms are often killed by a viral disease called nuclear polyhedrosis. The dead larvae turn black and become limp, often hanging from leaves. The body eventually disintegrates, releasing virus particles that readily spread to other larvae.

An armyworm killed by a viral disease
An armyworm killed by a viral disease


Statewide IPM Program, Agriculture and Natural Resources, University of California
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