DIPTERA. 



85 



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



-ach blow detaches a small portion of the substance of the leaf. It 

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



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



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



hen they are near their final transformation. 

 Section of Acalyptera. — The Ac'a/yJ>fera, which are^ the last of the 



reat tribe of MuscidcE, comprehend the greater number of these- 



isects. Their constitution appears 



3 be pecuHar and slow. They live 



rincipally in the thickest part of 



foods^ on grasses, and aquatic plants. 



''earing the lustre and warmth of the 



nn, they never draw the nectar from 



bwers. Their flight is feeble, and 



hey never indulge in those joyous 

 rthereal dances which we have men- 

 ioned when speaking of the preceding 

 proups. Their life is generally melan- 



holy, obscure, and hidden. Some 

 5f them seek decomposed animal and 

 ^regetable substances, others living 

 vegetables. 



: We shall only be able in this im- 

 mense group of Muscidce to mention 

 a few types which are interesting from 

 various reasons, such as the Helomyzce, 

 the Scaiophagce^ iheOrtalidce, 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 Helomyza. 



