Three insecticide tests against Heliothis populations from 1984 to 1986 in cotton demonstrate that a change in the manageability of these populations using insecticides has occurred. Heliothis populations, probably composed mainly of bollworms, Heliothis zea, were controlled with low rates of pyrethroids and other insecticides in 1984. However, a 1985 population composed largely of tobacco budworms (H. virescens) proved difficult to control. Similarly, a 1986 bollworm population containing a large number of larvae in excess of 1/2 inch in length was somewhat difficult to control.

The 1986 test showed that mixtures of insecticides from several classes were as effective or slightly more effective in controlling bollworm populations than were insecticides used alone. The mixtures compared favorably to products used alone even when rates of application in the combinations were reduced substantially.

A 1985 survey indicated that control problems were geographically wide spread. Additionally, they had occurred both in association with populations composed mainly of tobacco budworm and with populations composed predominantly of bollworms.