476 



DIPTERA 



1!. ^^'^vH 



it is a curious fact that the same sexual distinction of colour 

 reappears in various parts of the world — England, America, India, 

 and New Zealand ; moreover, this occurs in genera that are by 

 no means closely allied, although allied species frequently have 

 concolorous sexes. The eyes of the males are well worth study, 

 there being a very large upper portion, and, 

 abruptly separated from this, a smaller, differ- 

 ently faceted lower portion, practically a 

 separate eye ; though so largely developed the 

 upper eye is in some cases so hairy that it 

 must greatly interfere with the formation 

 of a continuous picture. Carriere con- 

 siders that the small lower eye of the male 

 corresponds to the whole eye of the female. 

 The larvae of Bibio (Fig. 225) are caterpillar- 

 like in form, have a horny head, well de- 

 veloped, biting mouth-organs, and spine-like 

 processes on the body-segments. They are 

 certified by good authorities-'^ to possess the ex- 

 tremely unusual number of ten pairs of spiracles; 

 a larva found at Cambridge, which we refer to 

 BiMo (Fig. 225) has nine pairs of moderate 

 spiracles, as well as a large terminal pair 

 separated from the others by a segment without 

 spiracles. The genus Biloplius is closely 

 allied to Bibio, the larvae of which (and those 

 of Bibionidae in general) are believed to feed 

 on vegetable substances ; the parasitism of 

 Dilo2)hus vulgaris on the larva of a moth, Einno- 

 FiG. 225. — Larva of tia {CIiaetoptHa) hypericana, as recorded by 

 Bibio sp. Cam- Meade,^ must therefore be an exceptional case. 

 In the genus Scato-pse there is a very im- 

 portant point to be cleared up as to the larval respiratory 

 system ; it is said by Dufour and Ferris ^ to be amphipneustic ; 

 there are, however, nine projections on each side of the body that 

 were considered by Bouche, and probably with good reason, to 





^ Osten Sacken, Berlin, ant. Zcitschr. xxxvii. 1892, p. 450. 



^ Eiitomolotjist, xiv. 1881, p. 287. This observation has never, we believe, been 

 confirmed. 



' Ann. Soc. ent. France (2) v. 1847, p. 46. 



