70 



THE INSECT WORLD. 



The MuscidcE form that great tribe of Diptera commonly known 

 as flies, which are distributed in such abundance over the whole 

 world. Faithful companions of plants, the flies follow them to the 

 utmost limits of vegetation. , At the same time they are called upon- 



by Nature to hasten the disso- 

 lution of dead bodies. They 

 place their eggs in the car- 

 cases of animals, and the 

 larvce prey upon the corrupt 

 flesh, thus quickly ridding the 

 earth of those fatal causes of 

 infection to its inhabitants. 

 The organs of these insects 

 are also infinitely modified, in 

 order to adapt them to their 

 various functions. 



M. Macquart divides the 

 MuscidiC into three sections 

 ■ — the Creophili, the Antho- 

 myidce^ and the Acalyptera. 



The Crcophiii \\d,\'^ the 

 strongest organisation ; their 

 movements and their flight 

 are rapid. The greater |mrt 

 feed on the juices of flowers, 

 some on the blood or the , 

 humours of animals. Some I 

 deposit their eggs on diflerent 

 kinds of insects, others on 

 bodies in a state of decom- 

 position, some again are 

 viviparous. The insects of 

 the genus Echinomyia^ for in- 

 stance (Fig. 51), derive their 

 nourishment from flowers. They deposit their eggs on caterpillars, 

 and the young larvae on hatching penetrate their bodies and feed on 

 their viscera. How surprised, sometimes, is the naturalist, who, after 

 carefully preserving a chrysalis, and awaiting day by day the ap- 

 pearance of the beautiful butterfly of which it is the coarse and 

 mysterious envelope, sees a cloud of flies emerge in place of it ! 



But there is another singular manoeuvre performed by some of 

 the species of the Diptera with which we are at present occupied, to 



Fig. 51. — Echinomyia grossa. 



