220 



SUBKIKGDOM ARTICULATA. 



eggs, side by side, with a thin layer of woody fibre between. 

 The larvae, on hatching, drop to the ground, in which they 



live for seven- 

 teen years, feed- 

 ing upon the 

 roots of trees. 

 When ready to 

 enter the pupa 

 state, they 

 make cylindrical burrows? 

 cemented water-tight, and 

 at length issuing forth, in 

 appearance like the imago 

 except the want of wings, 

 attach themselves to any 

 object at hand, particular- 



Jn fl 



Dru 



Seventeen-year Locust. 



short time, the thorax splitting on the back, 

 the perfect imago crawls out ; after pairing, 

 the female deposits its eggs, and the male 

 fills the air with the noise of the ear- 

 piercing kettle-drum beneath its wings.* 



Coreidae.-r-The Squash-bug hibernates 

 in crevices, but lays its eggs on the under 

 side of squash leaves. The young brood 

 are of a pale ash color, and, after molting 

 several times, appear in their perfect state 

 with wings and wing-covers. 



A p h i d ae (exhausters). Plant-lice f 

 have a wonderful life-history. The eggs 



Fig. 377. 



Coreus tristis, 

 Squash-bug. 



* This apparatus is concealed under two valves in the upper part of the 

 abdominal cavity. The membrane of the drum-head is thin, brittle, and slightly 

 wrinkled. There is a muscle attached to it on the inner side. By contracting 

 this, the drum-head is drawn in, but on relaxing, it springs back of itself, 

 thus producing the familiar clicking noise of the Cicada. The pupil can 

 easily make a dissection of the insect, and examine the apparatus for 

 himself. 



t Nothing can be more amusing than to watch the plant-lice for half an hour, 



