414 



ANIMAL BIOLOGY 



Beetles were eventually discovered which offered hope of meeting 

 the needs, and these were sent to California and reared until they 

 could be colonized in the infected groves. Here they multiplied 

 and ever since have held the Scale in check. (Figs. 264-266.) 



Fig. 264. — Australian Ladybird Beetle, Rodolia cardinalis, and Fluted 

 Scale-insect; Icerya purchasi. a, larvae of beetle feeding on scale; 6, pupa of 

 beetle; c, adult beetle; d, Orange twig showing scales and beetles. (From 

 Marlatt.) 



Furthermore we must not forget that such insects as the Silk- 

 worm Moth and the Honey Bee are really domesticated animals: 

 each is at the basis of an enormous world industry. One of Pas- 

 teur's most important studies was on the pebrine disease of 



A B 



Fig. 265. — A, An Ichneumon Fly inserting egg in an Aphid. B, emergence 

 of the parasite that has developed from the egg. (From Webster.) 



Silkworms, and not only saved the silk industry of France, but also 

 paved the way for the study of infectious diseases in higher animals 



