HABITS AND STRUCTUEE OF INSECTS. 97 



CHAPTEE XIII. 



HABITS AND STRUCTUEE OF INSECTS (CONTINUED). 



91. A LITTLE bug, called the tree-hopper, has a peculiar 

 history in its young state. The eggs of certain species are 

 laid in the ground, and, as soon as these hatch, the young 

 ones crawl up the stems of grass, and, piercing the grass with 

 their mouth-parts, commence to suck the juices contained 

 therein. While this action is going on, a clear, watery fluid 

 escapes from certain pores in the body, and in a short time 

 the young insect is completely immersed in it. As it is 

 obliged to breathe air, it secures this by turning up the 

 hinder part of the body, and by means of little appendages, 

 clasping a bubble of air, which then flows along the under 

 side of the abdomen ; here it is taken in through the spira- 

 cles. The air having been so used, is allowed to escape in 

 the fluid in which the insect is immersed. This operation 

 is repeated over and over again, fresh bubbles of air being 

 thus secured, and then escaping in the fluid. After a while 

 the fluid becomes filled with these little bubbles, which soon 

 convert it into a frothy substance, and this is the origin of 

 the white flecks which occur so thickly on grass, and which 

 is here commonly called frog-spit^ and, in England, cuckoo- 

 spittle. 



92. There are certain insects belonging to the same group 

 which are aquatic, and whose young come to the surface of 



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