150 INSECTS 



ditions for its greatest efficiency. But we can, at least, 

 follow up the spread of the insects with the disease, 

 and by getting the germs into every colony as fast as 

 it is established, introduce a check which is ready to 

 act when conditions become favorable, and which may, 

 in some localities, control it a?jsolutely. 



Only a small number of insects have been specifi- 

 cally mentioned as suiTering from disease attack; 

 but this does not begin to indicate the actual extent 

 to which they suffer, nor the varying character of the 

 infestations. And it is not only those species that live 

 above ground on trees or foliage that are affected. 

 Some of the underground forms like white grubs, wire- 

 worms and others are subject to the attacks of growths 

 which change the entire insect into a corky mass, giving 

 rise in some cases to processes that reach above ground 

 as though the grub itself had begun to sprout. The 

 extent to which such conditions occur we cannot esti- 

 mate because they are mostly out of our view; but we 

 do not find them often enough to indicate that they ex- 

 ercise any great influence upon the number of examples 

 that come to maturity. 



Among aquatic insects diseases also occur, and I 

 have frequently lost entire broods of mosquito larvas 

 that have been the subject of some trouble which caused 

 a cheesy degeneration. 



Every breeder of insects has had some of his cages 

 infected with disease germs so that every brood sub- 

 sequently introduced died ofif altogether or in large 

 part, and the experienced man to whom this happened 

 destroyed those cages altogether if he could, or cleaned, 

 disinfected and exposed them to the action of the sun 

 and air if for any reason keeping them was necessary. 

 He realized that, once established, a germ disease was 

 extremely difficult to get rid of by any but the most 



