86 



THE INSECT WORLu. 



opening the truffle, the larvse of the insect of which we are speaking 

 v/ill be found inside. These larvse are white and very transparent 

 Their mouth is armed with two black hooks, by means of which the) 

 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 become full-grown 

 They then leave their abode and go into the ground, there to chang( 

 into pupoe. 



The OrtalidcR form a tribe which is remarkable for the uprigh 

 carriage of the wings, which are generally speckled, by the vibrator 

 movement of these organs, and especially for the cradle chosen b 

 them for their progeny in fruits and grains. Nature seems to hav 

 assigned to each species its own particular vegetable. 



We will only mention here the Cherry-tree Ortalis, whose larv 

 lives on the pulp of that fruit. This fly is about a line and a ha' 

 long. It is of rather a metallic black colour, its head light yellov 

 the edges of its eyes white, and the tarsi red. The wings have foi 

 broad black stripes. 



The Olive Dacus {Dacus olece, Fig. 65) is a little fly, about ha 



the size of the house fly, of ash 

 grey colour on the back, i 

 head orange-yellow, its ey( 

 green, and its forehead yellow 

 marked with two large blac 

 spots. The thorax is adorne 

 with four lightish yellow spot 

 and its hind part, as well as i 

 antenna and wings, are of tli 

 same colour. The wings a • 

 transparent, reflecting gree 

 gold, pink, and blue, accordin 

 as the rays of light fall upo; 

 them, and are remarkable far having a small black spot at their e*: 

 tremity. The abdomen is of a fawn colour or orange-yellow, spottt: 

 with black on each side. This fly performs sudden and jerki i 

 movements ; it keeps its wings extended, and rather jumps than flii 

 It is a destructive insect, a perfect scourge, which causes every t^ 

 or three years a loss of five or six millions of francs to Fren 

 agriculture. 



M. Guerin-Meneville has made some valuable observations 

 the Olive Dacus, and at the request of the Imperial Society ;■ 

 Agriculture of Paris, has indicated the way to preserve the olive fr< i 



Fig. 65. — Dacus olese. 



