no 



A A' ECONOMIC ENTOMOLOGY. 



chances are now that the lady-birds will follow them and become 

 scarce or extinct, unless they show the power of adapting them- 



treatment becomes exceedingly expensive and practically useless. 



A curious series of species is found in the genus Kermes , often 

 found on oaks, and resembHng at first sight galls or even small 

 snail-shells, their texture being almost as brittle as if composed 

 of lime. They are never economically important, but curious 

 enough to deserve mention here. 



Next come what are known as " soft scales," usually of con- 

 siderable size and readily visible. Quite commonly they are 

 convex or nearly hemispherical, rarely quite regular in outline, 

 and sometimes ribbed or ridged. In most instances they are 

 brown in color, not very rigid in texture, and easily crushed ; 

 whence the term " soft scales." We have a number of injurious 

 species, and perhaps none more common than the ' ' cottony 

 maple scale, ' ' Pzilvinaria innumerabilis . Though called the maple 

 scale, and found most frequently on that tree, yet it is by no 

 means rare on grape, and often common on the Virginia creeper. 

 Sometimes it occurs on other plants as well, and is occasionally 



Icerya purchasi, female. 



Fig. 82. 



selves to surroundings, and 

 find other food to their likino^ ; 

 but while they have been use- 

 ful as against the Ice?ya, and 

 may have entirely destroyed 

 it, we cannot hope that they 

 will be equally successful in 

 coping with our native insects, 

 who have long since adapted 

 themselves to their surround- 

 ings in such a way as to make 

 it unlikely that any intro- 

 duced species will be effectual 

 in seriously lessening their 

 numbers. Insects of this char- 

 acter are susceptible of treat- 

 ment with the kerosene emul- 

 sion, although, where they 

 occur in such numbers as did 

 the Icerya in California, this 



