THE INSECT WORLD. 



The Mutides form that great tribe of Diptera commonly known 

 as flies, and 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 

 larvae 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 

 Muscides into three sections 

 the Creophili, the Antho- 

 myzides, and the Acalyptera. 



The Creophili have the 

 strongest organisation ; their 

 movements and their flight 

 are rapid. The greater part 

 feed on the juices of flowers, 

 some on the blood or the 

 humours of animals. Some 

 deposit their eggs on different 

 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. 



