510 



DIPTERA 



Doubtless there are many other interesting features to be found 

 in the life-histories of Tachinidae, for in numbers they are legion. 

 It is probable that we may have 200 species in Britain, and in 

 other parts of the world they are even more abundant, about 

 1000 species being known in North America.^ The family 

 Actiidae is at present somewhat doubtful. According to Karsch," 

 it is a sub-family of Tachinidae ; but the fourth longitudinal 

 vein, it appears, is straight. 



Fam. 36. Dexiidae. — These, Insects arc distinguished from 

 Tachinidae hy the bristle of the antennae hei^ig pubescent, and 

 the legs usually longer. The larvae, so far as known, are found 

 in various Insects, especially in Coleoptera, and have also been 

 found in snails. There are eleven British genera, and about a 

 score of species. 



Fam. 37. Sarcophagidae. — Distinguished from Muscidae 

 and Tachinidae hy little more them that the bristle cf the 

 antennae is feathery at the base but hair-like and very fine at' 

 the tij}. — Sarco-phaga, carnaria is one of the commonest British 

 Insects; it is like the Blow-fly, though rather longer, con- 

 spicuously grey and black, with the thorax distinctly striped, 

 and the pulvilli very conspicuous in the live fly. Cynomyia 

 mortuorum is a bright blue fly rather larger than the Blow-fly, 

 of which it is a competitor ; but in this country an unsuccessful 

 one. The larvae of the two Insects are found together, and are 

 said to be Cjuite indistinguishable. Cynomyia is said to lay only 

 about half the number of eggs that the Blow-fly does, but it 

 appears earlier in the year, and to this is attributed the fact 

 that it is not altogether crowded out of existence by the more 

 prolific CaUiphora. The species of Sarcophagidae are usually 

 viviparous, and one of them, Sarcophila magnifiea {vjohlfahrti), 

 has the habit of occasionally depositing its progeny in the 

 nostrils of mammals, and even of human Ijcings, causing horrible 

 sufferings and occasionally death : it is said to be not uncommon 

 in Europe, but does not occur in Britain. The genus Sarcophaga 

 is numerous in species, and many of them are beneficial. Sir 

 Sidney Saunders found in the Troad that Locusts were destroyed 

 by the larvae of a Sarcophaga living in their bodies ; and 



^ A list of the Insects known to be attacked by Dipterous parasites has been 

 given liy Braiier and Bergenstamm, BenTc. Ak. Wien, Ixi. 1805. 

 2 Berlin, ent. Zcit. xxx. 1886, p. 135. 



