Asilidae, Assassin Robber Fly

With regard to interspecific trophic relationships, there is a large number of reports on the prey captured by Asilidae. Lavigne (2003) has developed a database comprising over 13,000 reports Lavigne (2003). The prey of Asilidi are predominantly represented by other insects, mostly winged, but several cases in which they have attacked spiders have also been reported. Within the insects, orders that include the most frequent prey of asilids are the beetles, the Hymenoptera, the Diptera, the Hemiptera and Lepidoptera, with a wide range of families, but prey belonging to various other orders (Odonata, Neuroptera, Isoptera, Thysanoptera, Blattodea, etc.) are also mentioned.
With regard to the specificity of the trophic relationship Wood (1981) mentions the existence of some studies in the literature on the subject.Some genera have been found to be monophagic, but more generally the Asilidae manifest a more or less wide polyphagia with behaviors that vary from stenophagia to euriphagia. However, there are cases of stenohage asilids which if necessary focus their predatory activity against a species when this forms large populations.
Other studies conducted by Dennis, D. and Lavigne,(1975) have shown that the ratio between the size of the prey and the asilid varies from 1.8:1 to 3.7:1, with an average of 2. 6:1. The ratio tends to increase with decreasing size of the predator.
Egg-laying takes place, according to the species, with three different behaviors which relate to the structure and the morphology of the abdomen. Females with an undifferentiated ovipositor release eggs randomly and independently from the substrate. In other cases, however, the abdomen bears a differentiates, specialized ovipositor to lay eggs in the soil or sand, or lay them in cavities within plant tissues.