The larvae of certain gall midges have been known for a long time to prey on Aphids ; in fact Rondani in 1847 described a midge, now known as Phaenobremia aphidimyza, Rond., whose larvae fed on Aphids on fruit trees. Since this first record, there have been many notes of Aphids being attacked by Cecidomyid larvae, and in some cases the adult midge has been reared and described. Most of the literature consists of mere records of larvae feeding on Aphids or else descriptions of the midges ; in a few cases biological notes are added. So far as the writer knows there are only two papers that are devoted to a study of midges as a potential natural control of Aphids. Further work is badly needed to find out whether midge larvae can, or do, act as control agents. There have been vague statements that Aphids in certain outbreaks have been controlled by the midge larvae, but so far there have been no exact proofs based on counts of numbers of Aphids killed, fecundity of midge compared with Aphid, the appetite of the midge larvae, etc.