Please refer also to the following links for details on this group:
Drosophilidae = Link 1
The majority of species of Drosophilidae develop in decaying fungi, fruits and similar materials, but there is a small number which are predaceous or parasitic in habit. Larvae of genera Acletoxenus, Gitona and Gitonides are predaceous on Homoptera, and Titanochaeta ichneumon Knab was reared from spider egg sacs (Knab 1914). Gitonides perspicax Knab is a predator on mealybugs in Hawaii and Asia, and Pseudiastata brasiliensis C.L. attacks Pseudococcus in South America. Rhinoleucophenga obesa Lw. is predaceous in egg sacs of Aclerda campinensis Hemp. in Brazil, and an undetermined species is found in those of Orthesia in Brazil. Acletoxenus seems restricted in its host preferences to Aleyrodidae, and a short account of the habits of A. indica Malloch was given by Clausen & Berry 1932). In some parts of Java it is the dominant predator attacking Aleurocanthus spp. The eggs are somewhat oblong, measuring 0.4 X 0.2 mm., and are covered with a white waxy incrustation. They are laid singly on the leaf surface adjacent to mature host larvae or pupae. The larva is at first translucent white, but later becomes distinctly greenish. It is very sluggish and never moves from the leaf on which the egg was laid. A single host cluster provides ample food for its development. The larva in its later stages secretes an adhesive substance of the body which attaches various extraneous matter, including host exuviae, to it. Pupation occurs in situ on the leaf surface, and the developing fly can be readily seen through the semitransparent puparial wall. Empty puparia are noticeable among host colonies by their white color. The life cycle takes ca. 2 weeks (Clausen 1940/62).
The dominant genus Drosophila contains several species of questionable parasitic or predaceous habit. Bonnamour (1921) reared D. rubrostriata Beck. from caterpillars of Pieris brassicae L. confined with gravid females. Host larvae probably die by oviposition of the fly. Liquefaction of the body contents is rapid, and the larvae then feed mostly as scavengers. Drosophila paradoxa Lamb and D. inversa Wlk. have been found to attack nymphs of the cercopid genus Clastoptera in tropical America. Clausen (1940) noted that there is some question as to the role of the larvae attacking this host, as some researchers consider that they are inquilines, feeding mostly if not entirely on the spittle surrounding them. However, Lamb (1918) noted that half the masses contained D. paradoxa larvae, with their heads embedded in the bodies of the host nymphs. In D. inversa Baerg (1920) found that the larvae usually lie diagonally across the host's dorsum, with mandibles embedded in the 4th or 5th abdominal segment. He did not consider this species to be a true parasitoid but rather that it fed only on spittle. The fact that the larvae have a fixed position and embed the mandibles or even the entire head in the host body suggests a closer relationship than would be necessary for a scavenger (Clausen 1940/62). The larval habits and host relationships recall those of epipyropid larvae that are associated with Fulgoridae and related families (Clausen 1940/62).