So INSECTS 



Scale insects feed on the juices of their host as do 

 the plant lice, differing in the fact that they are more 

 or less fixed to a single spot on the plant: absolutely 

 fixed in the armored scales, with a very limited range 

 of motion during a part of their life in the soft scales; 

 the latter being in some cases not far removed from the 

 mealy bugs which are active throughout their life and 

 produce a powdery material that does not form a com- 

 plete covering. Some produce living young and breed 

 throughout the season, like the San Jose scale; others 

 are oviparous and have only one distinct brood, like the 

 cottony maple scale. In some there are only a few 

 eggs, in others they are almost uncountable, and thus 

 there is a great range in the life cycle, although the 

 nature of the injury done is always the same. 



One characteristic feature is the difference between 

 the sexes. The males, throughout the Coccidce, are 

 very minute, frail, two- winged creatures without func- 

 tional mouth parts and two pairs of eyes; one pair 

 replacing the lost feeding organs. These males are 

 often furnished with long anal styles or filaments, and 

 their only function is to fecundate the female. The 

 latter feeds throughout life, never becomes winged, and 

 her dead body often serves as a cover or shelter for the 

 egg mass that she produces. 



The injury caused is primarily due to the abstrac- 

 tion of sap; but quite a number of species produce a 

 distinct poisoning of the bast or bark tissue, often 

 evidenced by a red or purplish discoloration. Where 

 this occurs the twig or branch dies sooner or later. 

 Sometimes pits or depressions are formed where a 

 little group of scales is lodged and, in fact, there are 

 infinite variations in the character of the injury, due 

 to the peculiarities of the plant attacked and to the 

 method of feeding by the insects. Some of the soft 



