vii LOXCHOPTERIDAE MYDAIDAE ASILIDAE 491 



not noticed by Lubbock, but Frauenfeld 1 has since observed it, 

 though he only mentions that it possesses differentiated limbs 

 and segments. The metamorphoses appear to be very peculiar. 

 This fly requires a thorough study. 



Fam. 23. Mydaidae. Large flies of elongate form ; the hind 

 femora long and toothed beneath ; the antennae knobbed at the tip, 

 projecting, rather long, the basal joint definite, but the divisions 

 of the subsequent joints more or less indistinct. Empodium small. 

 Wings frequently heavily piamented ; ivith a complex nervuration. 

 These fine flies are exotic ; a few species occur in the Mediter- 

 ranean region, even in the South of Europe ; the chief genus, 

 Mydas, is South American, but most of the other genera are 

 Australian or African. But little is known as to the life- 

 histories. The larvae are thought to live in wood, and to prey 

 on Coleopterous larvae. 



Fam. 24. Asilidae (Robber -flies*}. Mouth forming a short, 

 projecting horny beak, the palpi usually only small ; the feet 

 generally largely developed ; the claws large, frequently thick and 

 blunt, the pulvilli generally elongate, the empodium a bristle ; 

 halteres free; no squama. The Asilidae is one of the largest 

 families of flies, and probably includes about 3000 described 

 species : as will readily be believed, there is much variety of 

 form ; some are short and thick and extremely hairy, superficially 

 resembling hairy bees, but the majority are more or less elongate, 

 the abdomen being specially long, and having eight segments 

 conspicuously displayed. The antennae are variable, but are 

 three -jointed with a terminal appendage of diverse form and 

 structure. They belong to the super-family Energopoda of Osten 

 Sacken, but the association of Empidae and Dolichopidae with them 

 does not seem to be very natural. In their perfect state these 

 flies are most voracious, their prey being Insects, which they 

 seize alive and impale with the rostrum. They are amongst 

 the most formidable of foes and fear nothing, wasps or other 

 stinging Insects being attacked and mastered by the stronger 

 species without difficulty. They have been observed to capture 

 even dragon-flies and tiger-beetles. As is the case with so many 

 other Insects that prey on living Insects, the appetite in the 

 Asilidae seems to be insatiable ; a single individual has been 

 observed to kill eight moths in twenty minutes. They have 

 1 Ferh. Ges. Wien, xix. 1869, p. 941. 



