( ^97 ) 



XII. NutcB Dipterolofficce. iVb. 1. — ^ombyVa at Pompeii. 

 By J. O. Westwood, M.A., Hon. M. Ent. 

 Soc. France, &c., Pres. Ent, Soc. 



[Read 1st March, 1876.] 



The youngest Entomologist cannot but have observed 

 ■with pleasure, in the spring months, the interesting flight 

 and movements of the two-winged flies belonging to the 

 genus Bomhylius. In the hottest sunshine some of these 

 flies are to be seen suspended, as it were, in the air, im- 

 moveably, the movements of the wings being so rapid as 

 to render them invisible ; but at once distinguishable by 

 their long and slender black proboscis, stretched out in 

 front of the head, and equalling in length the entire body of 

 the insect. Other individuals may be seen flying over hot 

 sandy banks, searching about the entrance of every hole 

 and crevice. Each of these particular movements has a 

 very distinct object, the former insects being the males, 

 which do nothing but revel in the sun-beams, whilst the 

 latter are the females, seeking for the nest of some luck- 

 less bee, already furnished with a supply of food for the 

 larva of the bee, when hatched from the o,^^ already de- 

 posited by the hard-working female bee in her cell. 



Thanks to the researches of previous observers, the eco- 

 nomy and transformations of the Bomhylii are now satis- 

 factorily known to Entomologists. Latreille rightly con- 

 sidered that the Bomhylii, like Anthrax, w^ere parasites, 

 contrary to the opinion of Zetterstedt that the larvae feed 

 on the roots of plants (Ins. Lapp. p. 510). The pupa of 

 Bomb, major was first figured by M. ImhofF in the Isis 

 for 1834, having been found by him in a situation which 

 he had previously noticed to be frequented by Andrena 

 humilis (vol. 1834, p. 536, pi. xii). In my Introduction 

 (vol. 2, p. 538, 1840), I published a figure of the same 

 pupa from a specimen discovered by Mr. C. Pickering in 

 a sandy gravel pit at Coombe Wood on the 28th of March, 

 from which the imago was produced in a few days. The 

 pupa is very similar to those of the species of Anthrax, 

 Avhich are known to be parasites, having the front and 

 underside of the head armed with strong spines, and the 



TRANS. ENT. SOC. 1870. — PART IV. (dEC.) 



