DIPTERA. 69 
these insects are also infinitely modified in order to adapt them to 
their various functions. 
M. Macquart divides the Muscides into three sections: the 
Creophilt, the Anthomyzides, 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 
decomposition, some again are 
viviparous. The insects of the 
genus Hchinomyia, for instance 
(Fig. 51), derive their nourish- 
ment from flowers. They de- 
posit their eggs on caterpillars, 
and the young larvee on hatch- 
ing 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 
appearance of the beautiful 
butterfly of which it is the 
coarse and mysterious enve- 
lope, sees a cloud of flies 
emerge in place of it ! 
But there is another singular manceuvre performed by some of 
the species of the Diptera, with which we are at present occupied, 
to prepare an abundant supply of provision for their larve as 
soon as they are hatched. ‘The following are the means they 
employ. Itis well known that certain fossorial Hymenoptera carry 
their prey, other insects which they have caught, weevils, flies, 
&c., and which they intend should serve as food for their 
own larve, into their subterranean abodes. These Diptera, 
spying a favourable moment, slip furtively into their retreats, and 

Fig. 51.—Echinomyia grossa. 
