DIPTEEA. 



85 



tion delicate. 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 mentioned when speaking of the preceding groups. 

 Their life is generally melancholy, obscure, and hidden. Some of 

 them search for decomposed animal and vegetable substances., 

 others living on vegetable matter. 



We shall only be able in this immense group of Muscidce to 

 mention a few types which are interesting from various reasons, 

 such as the Helomyza, the Scatophagi, the Ortalidte, the Dad, and 

 the Thyreophorce. 



The Helomyzas (Fig. 64) live in 

 the woods. Their larvae are developed 

 in the interior of fungi. Reaumur 

 studied the larva of the Truffle Helo- 

 myza. The head of this fly is ferru- 

 ginous, 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 

 opening the truffle, the larvae of the 

 insect of which we are speaking 

 will be found inside. These larvae 

 are white and very transparent. 

 Their mouth is armed with two black 

 hooks, by means of which they dig 



into the truffle in the same way as other larvae dig into meat. 

 The excretions of these little parasites cause the truffle to become 

 decomposed and rotten. In a few days the larvae are full-grown. 



Fig. 64. A species of Helomyza. 



