174 UOM.BYLIIDJB. 



Wings of moderate size or elongate. Venation conspicuous by 

 the absence of the posterior cross-vein, the upper branch of the 

 5th vein forming for a longer or shorter distance (rarely puncti- 

 form) the lower side of the discal cell. Subcostal cell usually 

 narrow, the auxiliary and 1st longitudinal veins sometimes almost 

 touching. Submarginal cells normally two or- three, rarely one 

 only (Cyrtosia), sometimes four (Hypcralonia) ; * 3rd vein simple 

 or forked, when the latter, the fork encloses the wing-tip. Discal 

 cell normally present, rarely absent.f Three or four posterior 

 cells ; anal cell open or closed. Wings bare, but the costa bears 

 small spines at the base, where there is often a patch of them of 

 considerable size, often intermixed with scales. Alulae small : 

 alar squamae rather large, with a thickly-set, rather long, broad, 

 flattened scale-like fringe (Anthrax), or with a woolly, long mar- 

 ginal fringe, or moderately developed, with a short delicate fringe. 

 JFrenum sometimes distinctly widened before the angle, and 

 bearing long hairs similar to those surrounding it, but otherwise 

 the thoracic squamae absent. Halteres small, often not easily 

 seen. 



Life-history. That of many species is more or less known. 

 They are mostly parasitic on Lepidoptera, especially on the genus 

 Acjrotts and other Noctuids : also on the larvae of bees, wasps, 

 ichneumons and Tachinids that are themselves parasitic on Lepi- 

 dopterous larvae. Callistoma is parasitic in the egg-capsules of 

 a locust. The Bombyliid larva is amphipneustic, cylindrical, 

 rather flattened, 13-segmented ; an obvious, though small, re- 

 tractile head with well developed mouth-parts, papillate antennae, 

 and no eyes. The young larva is elongate, each thoracic seg- 

 ment with a pair of long setae, the penultimate segment with two 

 spiracles: the adult larva is obese and without setae. Pupa free, 

 mummy-like, with strong spines on head and anterior part ; 

 abdominal segments with chitinous booklets. The pupa has pro- 

 thoracic and seven pairs of abdominal spiracles, some species 

 bearing transverse rows of spines on most of the segments. The 

 BOMBYLIIDJE contain many of the most brilliantly coloured Diptera 

 and attain considerable size, the wings being frequently verv 

 prettily marked, whilst the body is often adorned with bright 

 tufts of gorgeous pubescence or patches of coloured scales. The 

 family is a very large one and is of world-wide range, occurring 

 mostly in dry sunny or sandy localities, many of the species being 

 exquisite hoverers. The members of the family may be recognised 

 by absence of the posterior cross-vein (although this is not alwavs 

 obvious to the inexperienced), the few posterior cells, and the 

 furry pubescence of most of the species. They are most nearly 

 related to the CYRTID.E and the THEREVIDJE. 



* Additional cross-veins occasionally cause five submarginal cells in indi- 

 viduals, or, more rarely, in species, 

 t Cyrtosia, and Apolysis, for example, amongst Paltearctic genera. 



