A small plot yield enhancement study was conducted over a 2-year period (1985-1986) at the Red River Research Station in northwest Louisiana. Insecticides included in the yield enhancement study were chlordimeform, methylparathion (microencapsulated), cypermethrin, and a cypermethrin-chlordimeform combination. Four applications were made at a 5-9 day interval beginning at the pinhead square stage. The cypermethrin treatments (cypermethrin alone and in combination with chlordimeform) significantly reduced the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), - cotton fleahopper. Pseudatomoscelis seriatus (Reuter), complex (TPB-CFH) compared with the other treatments and the untreated check. Insecticide treatments had no significant effect on plant weight, height, or number of mainstem nodes. The cypermethrin treatments in 1985 and the chlordimeform treatment in 1986 significantly increased boll retention compared with the untreated check. Only the chlordimeform plot in 1985 produced significantly more seed cotton/acre than the untreated check. Insecticide treatments had no significant effect on number of open bolls/plant, rams of seed cotton/plant, and grams of seed cotton/boll. In 1985, treatments significantly affected the location of bolls along the mainstem. No adverse effects on plant vegetative or reproduction growth were noted with the use of 'microencapsulated' methyl parathion.