Cotton, Gossypium hirsutum has been grown in the Mexico state of Tamaulipas for the last six years. Production areas have varied but the trend is to increase, particularly since NAFTA has made other crops less attractive. Insect pest control is a key variable. The boll weevil, Anthonomus grandis grandis Boheman, cotton fleahopper, Pseudatomoscellis seriatus (Reuter) and the bollworm Helicoverpa zea (Boddie) and tobacco budworm (TBW), Heliothis virescens (Fabricius) are among the insects that generally require chemical control.

Bollworm and TBW larvae were collected during the cotton season and kept in diet under controlled conditions to determine the fluctuation of species and parasitoids. Field data collected to check the presence of these two species showed that during the first weeks of fruiting, TBW comprised more than 50% of the field-collected larvae.

Information collected since 1990 in Tamaulipas shows that natural enemies of the bollworm and TBW play an important role in suppressing them. Based on predator data, hemipterans were more abundant than any other species during the 1995 cotton season. Hot days and low rainfalll exacerbated the insect pest problem, with the ocurrence of damaging populations of the silver leaf white fly and aphids.