In the summer of 1989, a large scale experiment was conducted to study cotton enriched under "natural" field conditions using free air carbon dioxide enrichment (FACE). Computer-controlled releases of CO₂ were adjusted for wind direction and velocity in four 22-meter diameter rings in a underground drip irrigated field of Deltapine 77 cotton. Four control plots of equal area were also monitored. Thrips (Franklinielia occidentalis) were abundant enough to cause economic damage to the cotton early in the season and control measures were applied. CO₂ enriched cotton plants shed thrip-damaged leaves rapidly whereas ambient plants retained the damaged leaves. Other pesticide applications were made as deemed necessary as the field was managed as a commercial "money making" enterprise. Foliage feeders (beet armyworm, Spodoiotera exigua and cabbage loopers and bollworms, Heliothis spp.) did not do significantly different damage to foliage but damage to fruiting structures was higher in CO₂ enriched cotton and approached significance (P<0.04). By the end of July, the CO₂ enriched cotton had a heavier boll load than control cotton. It also was measured to be slightly hotter and drier. Additionally by day 199, it also had serious problems with spider mites (Tetranychus urticae) not present to the same degree in the control cotton. All plants were sampled for mite colonies and for damage using a ranking system. A mean ranking value of 668.3 for CO₂ enriched cotton compared to 122.0 for ambient cotton was significant by Chi Sq. at P<0.01. This increase in damage from spider mites (two-spotted) followed the same sequence reported previously in the literature when early season control against thrips was initiated and also when methyparathion was used. The difference in the damage appeared to be the fact that the CO₂ enriched cotton was hotter and drier. Despite vigilant control measures, spider mites colonies built up again in Sept. (day 258) and were significantly higher in CO₂ enriched cotton (P<0.005). A similar build-up occurred with the sweet potato whitefly (SPW), Bemisia tabaci, in the CO₂ enriched cotton by mid Sept. (day 258). A survey for adult SPW with yellow sticky boards produced a mean SPW count of 10,495 in CO₂ enriched cotton compared to 4,890 for SPW in ambient cotton (P<0.01, Chi Sq.). It is apparent that CO₂ enriched cotton is very different from present ambient cotton and arthropods respond differently to it. Although the changing greenhouse gases may alter population of arthropods important to crop production, a cautious approach must be taken in drawing conclusions from the work to date. Each episode must be viewed in the circumstances in which it occurred until patterns that can be supported emerge.