Nutritive and Ecological Requirements of Robber Flies (Diptera: Brachycera: Asilidae)
Ecological and ethological studies on robber flies exhibit the different importance of predatory habits for distinct developmental stages of their life cycle. Hitherto, predation has been established only for the imagines. This report should mainly point out the problems of the larval stages in immobilizing and ingesting their prey, and to indicate the role they play in insect communities. The hitherto almost unknown entomophagous behaviour of the larvae can now be elucidated in its trophic diversity, compared with the more uniform habits of the imagines. Field and laboratory investigations have shown that larvae of Asilidae do not eat vegetable food, although they can absorb water from the soil with all its dissolved organic and mineral components. In their life cycle, individuals of Machimus rusticus (Meigen 1820) pass the following trophic types: (L1) no intake of food other than yolk from the egg, (L2) micropredation on tiny animals, (L3 - L7) predation on other insect larvae.