90 Ortliorrhapha brachycera. 



d'Herculais, Bull. se. de la Fr. et de la Belg. XXXIX, 141]). Some of 

 the larvæ {Argyramoeba, Bomhylius) are known lo pass through dif- 

 ferent stages during growth, altering their shape by the moultings, 

 and are in the first stage rather active and provided with bristles 

 on the thoraclc segments and at the apex of abdomen; this will 

 probably prove to be the case with all Bombyliid larvæ. hi most 

 cases the full-grown larva hibernates and pupation and development 

 of the imago follow next summer^ but sometimes it seems to be the 

 egg or the young larva that hibernates (see under Bomhylius). When 

 the larvæ live in bee-cells, they devour and destroy the host larva, 

 but when they live on Ichneumonids, Tachinids and Lepidopterous 

 larvæ the host larva seems always to reach to pupation before being 

 destroyed; yet the Systropus larva devours the larva of the Sibine 

 and rests lying in the strong cocoon of this form. The larvæ hibernate in 

 the bee-cell or the cocoon or in the Lepidopterous pupa or the Locust 

 egg-case, and here the pupa is formed. When the time for the escape 

 of the imago comes, the pupa works through the hard wall of 

 the bee-cell or of the cocoon or egg-case out to the surface, often 

 some way through the ground, by aid of its armature; on escaping 

 the pupa-skin remains sticking in the hole in the bee-cell or the 

 ground. 



The egg-deposition has only been observed in a single case. 

 Algernon Ghapman (Ent. JMonth. Mag. XIV, 1878, 196) saw a small 

 Bombylius deposlt its eggs; it was on the wing and then approached 

 the ground within an inch or so jerking the eggs singly on the 

 ground. Fabre (Souvenirs Ent. III, 1886, 197) saw Argyramoeba 

 anthrax (simiata) flying in a similar way, probably also depositing 

 the eggs. It is very probable that the eggs are always laid on the 

 ground, and it is then the larva in its fust, active stage which arrives 

 at the host. 



The Bombyliids are small to somewhat large flies; they are of a 

 very characteristic appearance; some are clothed with a dense fur 

 (Bombylu) and hence more or less bee-like, others are less densely 

 clothed with long hairs, but are covered with depressed, scaly hairs 

 {Anthracinae). They occur especially on sandy localities, (as in our 

 country such localities are for the most part found at the shore, 

 the Bombyliids are with us especially found there), and they fly 

 very quickly in the hottest sunshine though also often seen sitting on 

 the ground. 



^ About retardation of the larval stage, this being prolonged over more than 

 one vear, see Rilev 1. c. 444. 



