Thrips are important pests on seedling cotton in South Carolina. Small grains--primarily wheat--and many species of wild plants serve as hosts for thrips prior to the availability of cotton. We conducted thrips surveys in two wheat fields in each of the following counties: Darlington, Dillon, Lee, Marlboro, and Sumter in 1991 and 1992, beginning April 3 and continuing through plant maturity. Thrips surveys were conducted in adjacent cotton fields beginning at plant emergence and continuing for 3 to 4 weeks. Thrips populations were also sampled on the following wild plants: wild mustard, Sinapis arvensis L.; old-field toadflax, Linaria canadensis (L) Dumort; and red sorrel, Runex aceosella L.

The species composition of thrips collected most abundantly in wheat in 1991 was as follows: grain thrips, Limothrips cerealium (Haliday), 52%; eastern flower thrips, Frankliniella tritici (Fitch), 28%; tobacco thrips, F. fusca (Hinds), 10%; and western flower thrips F. occidentalis (Pergande), 8%. In cotton, the principal species were F. occidentalis (Pergande) and F. fusca (Hinds), comprising 73% and 20% of collections respectively. F. tritici and L. cerealium each comprised 2% of collections. F. occidentalis was collected in abundance from S. arvensis in 1991 (April 15 to May 29) at the rate of about 6 per bloom. On L. canadensis and R. acetosella, the collection rates of F. occidentalis were 0.96 and 0.1 per plant. Each of these wild hosts is widely distributed in South Carolina.

In 1992, the thrips collected in wheat were 40% L. cerealium and 50% F. occidentalis and F. tritici. Thrips collections from cotton in 1992 were 95% F. occidentalis and F. tritici. Frankliniella species are yet to be determined, but the data collected in 1991 and other recent years suggest that the majority will be F. occidentalis.