antra-specific as well as inter-specific competition between three cereal aphids Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (L.) and Schizaphis graminum (Rand.) were studied under laboratory conditions. antra-specific competition of the nymphal stages of the three aphids un­der study induced the appearance of winged forms. When nymphs were reared separately, no or few alatae were produced, but rearing them in groups caused remarkable increase in formation of winged adults. The percentage survival of these nymphs also noticeably decreased as the level of crowding increased. Crowding of mothers resulted in significant decrease in the mean total progeny per female as the level of crowding was increased from one to five to ten females per cage. Clear reduction in the mean total progeny of a single female was also achieved when the progeny were left to feed with their mother than when nymphs were re­moved daily. Inter-specific competition between adults of any of the studied aphids did not show any appreciable reduction in the mean total progeny when reared together than when reared separately. These results indi­cate that intra-specific competition (without starvation was more effec­tive on the mean total progeny than inter-specific competition.