Some species produce a loud buzzing sound in flight not unlike some bumblebees. The curious Chilean asilid Lycomya germainii Bigot has for its model the Hymenopteron Elaphroptera scoliaeformis Haliday. The American series of mimics from the southwestern states copy the tarantula huntung wasps of the genus Pepsis Fabricius. These noteworthy insects are large, with black or blue-black bodies and wings strikingly colored a yellowish brown. Besides the robber fly Asilus midas Brauer, the series contains Mydas xanthopterus Loew, two large staphylinid beetles, and a large, conspicuous ichneumonid-type wasp.
Cryptic coloration exists in some forms.
Desert species especially tend to match the sandy background and many Laphriini and species of the Atomosini and species of Andrenosoma Rondani match the bark on which they rest. Death feigning has been observed in some captured asilids and has been remarked by Teale. I have noted that Proctacanthus milbertii Macquart may remain in catalepsy from several seconds to several minutes. How often this state is reached or occurs under natural conditions isnot known.