INSECTS. 



123 



(Ptyelus) is common in the grass in early summer. When 

 hatched, the young crawl up blades of grass, puncture 

 them with their mouths, and suck the juice, a watery fluid 

 escaping from various pores of the insect and completely 

 covering it. To obtain air, its tail is thrust through the 

 fluid (Fig. 150, 0), seizing a bubble by means of claspers, 

 that passes along beneath the abdomen, entering the spi- 

 racles. After a time the liquid becomes filled with air, 

 , and assumes the frothy appearance familiar as frog- 

 spittle, from which the perfect insect finally escapes. 



Bark-Lice 

 (Coccida). The 

 bark-lice are mi- 

 nute scale-like in- 

 sects, the males 

 alone having wings. 

 The cochineal 

 (Fig. 151) is a fa- 

 miliar form of the 

 family. 



VALUE. The coch- 

 ineal industry givesem- 

 ployment to thousands 

 of persons. From Coc- 

 cus siensis comes wax ; 

 400,000 pounds have 

 been obtained in a sin- 

 gle year, and made into 

 candles, etc. 



FIG. 151. i, Cochineal insects on a branch of 

 cactus ; 2, female ; 3, male. 



Plant-Lice (Aphida) These insects (Fig. 152) have 

 flask-shaped bodies and a three-jointed beak. They mul- 

 tiply in a marvelous manner. Eggs are deposited by the 

 impregnated female in the autumn that hatch in the spring, 

 producing, as a rule, wingless forms, that in turn produce 

 not eggs but living winged or wingless young, that in ten 

 or eleven days produce others, and so on, so that the origi- 



