Abstract
The application of a nuclear-polyhedrosis virus and Bacillus thuringiensis Berliner spores by helicopter resulted in a high rate of infection of colonies of the tent caterpillar, Malacosoma fragile incurva Henry Edwards. The incidence of diseased colonies, i.e. colonies containing at least 1 virus-killed larva, increased with increases in spray deposit and time (days) after spraying. Populations were 95% lower in the sprayed area than in the unsprayed area the year following treatment.