122 



THE STUDY OF INSECTS 



The tortoise or soft scales. — The tortoise scales are so-called because 

 the bodies of the females are usually shaped like the shell of a tortoise. 

 The body of the female is cleft at the caudal end and, in our more 

 common forms, is unprotected by wax or other form of covering. They 

 are, therefore, often called soft scales. 



Legs are present in the first and usually in the second stage nymphs 

 and the first stage nymphs are especially active. The adult females 

 are usually well fixed to their host-plant. 



Many of them excrete very little wax, the body being practically 

 naked, and the eggs, or the young in the viviparous species, are deposited 

 beneath the body; in other species, although the body is nearly naked, 

 the adult female excretes a large, cottony egg-sac; and in still others the 

 body is deeply encased in wax. 



The soft scale, Lecanium hesperidum, is the commonest and most 

 widely spread member of this subfamily; it infests a great variety of 

 plants; in the North, it is very common in greenhouses; in the warmer 

 parts of the country it lives out of doors. See Figure 206b, page 124. 



The members of the genus, 

 Puhinaria, include species in 

 which the body of the fe- 

 male resembles Lecanium but 

 which excrete a large cottony 

 egg-sac. The cottony maple 

 scale, Puhinaria vitis, is 

 common on the maple, osage 

 orange, grape, and other 



Fig. 203. — Puhinaria vitis. 

 sacs, on grape, natural size 



plants (Fig. 203). 



Females, with large cottony egg- 



THE NON-MOTILE COCCIDS 



The greater number of the common 

 scale insects of this country, especially 

 those which are of economic importance, 

 are fixed to the host-plant in the adult 

 (female) stage. The legs of the newly 

 hatched female nymphs are lost in the first 

 molt and the adult female becomes incap- 

 able of movement. 



The armored scales. — The great ma- 

 jority of the common scale insects of this 

 country differ from the forms already de- 

 scribed in that the body of the insect, 

 except for a very short period after birth, 

 is covered with a scale composed in part 

 of a waxy excretion of the insect and 

 partly of molted skins. In the lecaniums 

 the scale-like object is the body of the 

 insect ; but in the case of the oyster-shell 

 bark-louse (Fig. 204), the San Jose scale 

 and of many other forms, the scale-like object commonly seen is not the 

 insect, but a waxy armor beneath which it lives. 



The young insects of this group resemble in general appearance those 



Fig. 204. — The oyster-shell bark louse, 

 Lepidosaphes ulmi; the young appear as white 

 dots. 



