Bombyliidae. 89 



Iower hind corner of the discai cell, indicating incipient division 

 into two cells); (in sonie non-Danish genera there are only three 

 posterior cells); the first posterior cell is often narrowed at the apex 

 or closed at a shorter or longer distance from the margin. The anal 

 cell reaching to or near to the margin, narrowly open or closed. 

 Alula well developed. Alar squanmla present, generally fringed at 

 the margin, often with somewhat scaly hairs; thoracic squamula not 

 developed; the frenulum distinct, sometimes somewhat broad towards 

 the angulus, generally with long hairs, rarely bare {Phthiria). At the 

 base of the costa there is often a hook, (the præalar hook Osten 

 Sacken; this name is not good as the hook is in faet situated on 

 the costa). In rest the wings are borne half open and directed slightly 

 downwards, they are generally open to such a degree that the anterior 

 margins of the two wings are almost rectangular, sometimes they are 

 more spread. The wing-membrane of the Bombyliids is of a charac- 

 teristic stiff consistency, but somewhat fragile. 



The larvæ are cylindrical or somewhat flattened; the body con- 

 sists of thirteen segments; the head is small, retractile; the mouth 

 parts consist of a median labrum, knife-shaped, compressed, often 

 somewhat serrated mandibles and larger and broader maxillæ with a 

 palpus; the mandibles and maxillæ are movable up and down. Small 

 antennal papillæ are present. There are no eyes, The larvæ are 

 amphipneustic with spiracles on prothorax and on the penultimate 

 segment. — The pupæ are free; they have.characteristically arranged 

 spines on the head at the base and at the end of the antennal sheaths ; 

 the abdominal segments on the dorsal side are armed with charac- 

 teristic chitinous hooklets, formed as small staves or more or less 

 semicircular; moreover there are some spines at the apex of the body, 

 and the abdominal segments have girdles of shorter or longei- bristles 

 or hairs. The pupa has prothoracic and seven pairs of abdominal 

 spiracles. 



The larvæ live parasitically on larvæ of solitary bees and wasps 

 or fossorial wasps {Argyramoeba, Toxophora [Ost. Sack. Bull. U. S. Geol. 

 and Geogr. Surv. of the Terr. III, 265]), on larvæ of Ichneumonids and 

 Tachinids parasitical on Lepidopterous larvæ {Hemipenthea and some spe- 

 cies of Anthrax), on larvæ of Noctuidæ (some species of Anthrax), in the 

 egg-cases of Locustids (some species of Anthrax, CoUostoma [Saunders, 

 Transact.Ent. Soc. Lond. 1881, Tab. XIV, Proceed. XIV], Mulio [Stépanoflf, 

 Verh. Nat. Ges. Gharkow, XV, 1881] Aphoebantus [Riley, Sec. Rep. U. S. 

 Ent. Commis. for 1878—79, 1880, pi. XVI and Amer. x\at. XV, 439, 

 pi. VI] and Sijstoechus), on larvæ of solitary bees {Bombijlius) and on 

 Lepidopterous larvæ of the familly Limacodidæ {Systropus [Kiinckel 



