4 o8 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



In California millions of living ladybird-beetles are gathered 

 each winter, while hibernating in great masses in the high 

 Sierras, and as soon as the aphids begin to appear in destructive 

 numbers in the melon fields and other places large shipments of 

 the beetles are sent to the infested regions. 



The larva? of the lace-winged-flies and the syrphus-flies are 

 also great enemies of aphis and other soft-bodied insects. 

 The predaceous ground-beetles (family Carabidce) and the 

 tiger-beetles (family CincindeHdee] destroy many larva? and 



FIG. 190. The fluted scale, Icerya purchasi, attacked by the Australian 

 ladybird-beetle, Nomus cardinalis. In the lower left-hand corner, a 

 Novius which has just issued from its pupal case. (Upper figure slightly 

 enlarged; lower figure much enlarged.) 



adult insects that can be captured on the ground. The 

 assassin-bugs (family Redumida) are all predaceous, as are 

 several other kinds of Hemiptera. We have already called 

 attention to the importance of dragon-flies in controlling 

 mosquitoes. 



Among the parasitic insects the tachina-flies (family 

 Tachinidce) rank high as enemies of various kinds of caterpillars. 

 The eggs are usually laid on the body of the insect into which 

 the young make their way as soon as they are hatched. Here 

 they feed, often without destroying the host until it pupates. 

 Sometimes the eggs of the tachina-flies are laid on the leaves, 



