Cotton was planted in a factorial combination of 3 irrigation schedules and 4 plant populations in a randomized complete block design. Each treatment combination was sampled on 3 dates with a vacuum insect sampler.Lygus hesperusKnight, a complex of leafhoppers (Empoasca),Geocoris pallensStal, andOrius tristicolorWhite were present in large numbers. Significant differences in insect numbers between plant populations and/or between irrigation regimens were determined for each species or species group on one or more of the 3 sampling dates. Generally, insect populations were greatest at higher plant densities and with more frequent irrigation, factors which increased the density of plant canopies.