400 Syrphidae. 



margin of the first abdominal segment above are two, somewhat 

 approximated and diverging spiracular tubes. The colour is brownish, 

 The length of the pupa of pellucens (the only one I have examined) 

 is 13 mm. 



As seen above the larvæ live in the nests of Bombus and Vespa ; 

 they were originally thought to be parasitic, eating the larvæ and 

 pupæ of their hosts, but the observations of Erné (1. c.) and of Sharp 

 (Gambr. Nat. Hist. VI, 1899, 500) seem to prove that they are scavengers, 

 only feeding on deeeased larvæ and pupæ ; already Smith (Trans. Ent. 

 Soc. London, I, 1851, Proc. 111) thought that the larva of V. homhylans 

 in the nests of Bombus lived of honey and wax. Recently Sundvik 

 has (Meddel. Soc. pro Faun. Flor. Fen. 37, 1911, 56) revived the 

 suggestions towards their being parasitic, and has advanced the sup- 

 position that they dissolve the wasp-cocoon by a secret from glands 

 present in the posterior end of their body; the six longer threads 

 behind should then be used to hold the cocoon; these are, how- 

 ever, mere suggestions and, I think, of no value. The eggs have often 

 been found laid in the nests. The larva hibernates as fullgrovvn, 

 generally in the earth below the nests, and it pupates and develops 

 the next spring or summer. The habits of the larvæ mentioned here 

 hold good at all events for the European species, but with regard to 

 the American species V. fasciata Macq. it is recorded that the larva 

 feeds in the cactus Opuntia missouriensis. 



The species of Volucella show, as seen, generally more or less 

 resemblance to- wasps or Bombi; this is especially the case with 

 hombylans^ the two varieties of which are similar to B. lapidarius and 

 terrestris (or allied species). It has been thought that this was mimicry, 

 protective against the hosts, or, as it was found that the Volucella is 

 a welcome scavenger, indicating them as friends. It is, however, very 

 doubtful whether the resemblance has anything to do with mimicry; 

 thus bombylans is found also in nests of V. germanica, to which it has 

 not the slightest resemblance, and pellucens has likewise no resem- 

 blance to F. vulgaris, in the nests of which its larvæ are found ; more- 

 over Kiinckel d'Herculais says that he has bred the varieties of hom- 

 hylans from the same Bombus-nesX. 



The species of Volucella are large, beautiful flies, as said generally 

 more or less resembling species of Vespa or Bomhus-, they occur in 

 wooded districts and are found on leaves and on various flowers. 

 The genus is especially tropical with only a few species towards the 

 north but with a large number in southern regions. 



Of the genus 12 species are known from the palæarctic region, 

 but of these only 6 are European; 3 occur in Denmark. 



