DIPTERA. 



this digging is visible, as those places become by degrees transparent. 

 Each blow detaches a small portion of the substance of the leaf. It 

 is thus that these miners hollow out galleries for themselves, in which 

 they find shelter, food, and security. Some are changed into pupae in 

 the gallery which they have hollowed out, others go out of the leaves 

 when they are near their final transformation. 



Section of Acalyptera. The Acalyptera, which are the last of the 

 great tribe of Muscidcz, comprehend the greater number of these 

 insects. Their constitution appears 

 to be peculiar and slow. They live 

 principally in the thickest part of 

 woods, on grasses, and aquatic plants. 

 Fearing the lustre and warmth of the 

 sun, they never draw the nectar from 

 flowers. Their flight is feeble, and 

 they never indulge in those joyous 

 ethereal dances which we have men- 

 tioned when speaking of the preceding 

 groups. Their life is generally melan- 

 choly, obscure, and hidden. Some 

 of them seek decomposed animal and 

 vegetable substances, others living 

 vegetables. 



We shall only be able in this im- 

 mense group of Musridce to mention 

 a few types which are interesting from 

 various reasons, such as the Helomyzce, 

 the Scatophagce, the Ortalides, the Dad, 

 and the Thyreophorce. 



The Helomyzce (Fig. 64) live in 

 the woods. Their larvae are deve- 

 loped in the interior of fungi. Reau- 

 mur studied the larvae of the Truffle 

 Helomyza. The head of this fly is 

 ferruginous, its thorax is of a brownish 

 grey, its shoulders of a brownish yel- 

 low, its wings brownish, the abdomen 

 yellow and brown, and the feet red. 

 The larvae of these insects commit depredations for which gourmands 

 will never forgive them, destroying, as they do, their truffles. When 

 one presses between one's fingers a truffle that is in a too advanced 

 state, one feels certain soft parts, which yield under pressure. On 



Fig. 64. A species of Helomys 



