To determine species composition, thrips were collected from cultivar resistance tests from 1998 to 2000 and identified. In 1998, thrips species composition at Lonoke, Arkansas consisted of > 99% Frankliniella fusca. During 1999 and 2000, the composition at this location has changed to include more Frankliniella occidentalis. Also at Lonoke, population increase was evaluated by sampling thrips on a daily basis to determine the number of adult and larval thrips present on cotton. A zero baseline could not be established due to thrips being present before the cotton had fully emerged from the ground. Heavy rainfall had a detrimental effect on adult and larval thrips populations often reducing their numbers dramatically.