CONTROLLING INSECT PESTS 



407 



the notable exception of the introduced English sparrow and 

 of the few species of native sap-suckers, and two kinds of 

 hawks, practically all of our birds are to be regarded as friends 

 and helpers on the farm or in the orchard. 



The common garden toads eat many insects and worms 

 during the evenings while they are feeding. Spiders trap and 

 destroy many of the smaller insects and are especially 

 serviceable on small flowering bushes and garden plants. 



But it is to the insects them- 

 selves that we must look for some 

 of the most destructive enemies 

 of others of their class. It will 

 be convenient in considering 

 these to divide them into two 

 groups; first the predaceous in- 

 sects, which run or fly about 

 attacking and devouring other 

 insect species, and, second, the 

 parasitic insects, which spend a 

 part or all of their lives in or on 

 the body of their hosts. 



Among the predaceous insects 

 the ladybird-beetles are per- 

 haps the most important, as in both the adult and larval 

 stages they destroy great numbers of plant-lice, scale-insects 

 and other noxious insects. A remarkable example of the good 

 that they may do is furnished by the Australian ladybird- 

 beetle, Novius cardinalis, that was introduced into California 

 to aid in controlling the cottony-cushion scale, Icerya purchasi, 

 a pest that threatened the destruction of the citrus fruit in- 

 dustry in California. So rapidly did the beetles multiply 

 and so effectively did they do their work that the scale was 

 soon under control and is no longer regarded as a serious pest. 

 Many other species of ladybird-beetles have been introduced 

 into this country, but none has been so successful in its work as 

 this one. 



Many of our native species of ladybird-beetles are par- 

 ticularly destructive to certain kinds of aphis and scale-insects. 



FIG. 189.- A ladybird-beetle, 

 Coccinclla californica; larva, 

 pupae, and adult on Lawson's 

 cypress. (Twice natural size.) 



