This is a third of a series of papers dealing with zoophagous gall midges of the world. The first, “ Gall Midges as Enemies of Aphids,” was published in 1929 (Bull. Ent. Res., xx, 1929, pp. 433–442) and the second, “ Gall Midges as Enemies of the Tingidae, Psyllidae, Aleyrodidae, and Coccidae,” appeared more recently (op. cit., xxi, 1930, pp. 319–329).

In this paper the species of gall midges whose larvae have been reported as preying on mites are dealt with, the first reference mentioned being in each case that of the original description or record. Practically all the literature available consists of specific descriptions and little is stated about the bionomics of the species with a few exceptions. It is a matter for regret that such scant attention has been paid to this aspect of biological control, especially in view of certain statements claiming that the larvae of various gall midges are of considerable importance in the natural control of red spider. It is with a view to stimulating further research in this direction that the present paper has been compiled.

It has been thought advisable to divide the paper somewhat arbitrarily into separate sections, dealing firstly with those species of gall midges preying on free-living mites and secondly with those species preying on gall-inhabiting mites. A further section deals with those Cecidomyids which may feed on mites. As an additional convenience, a list of plants on which the mites live is appended. The Cecidomyids which may be predacious on mites (see section 5) are not, however, included in this list.