482 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



six or eight weeks from the time they are deposited and the young 

 cicada larvae emerge and fall to the ground. They then burrow 

 beneath the surface and enter upon their long menial existence 

 in the ground, feeding on the liquids of roots and possibly sub- 

 sisting on such nutriment as may be obtained from the soil itself. 

 They change their position from time to time, and may rarely 

 enter the earth for a distance of eight to ten feet or more," though 

 usually within two feet of the surface. "By the twelfth or thir- 



FIG. 407. The full-grown nymphs of the periodical cicada in different stages 

 of molting and the newly emerged adults with body and wings still soft 

 and white. 



teenth year the larva attains its full growth and in time changes 

 to the intermediate or pupa stage.* During the spring of the 

 fifteenth and sixteenth years great numbers of the pupae may be 



* Dr. Hopkins and other writers commonly use the terms larva and pupa 

 in describing the immature stages of the cicada, but there seems no reason 

 for discarding the term nymph used for other Hemiptera, and which is cer- 

 tainly useful in distinguishing the immature stages of insects with incom- 

 plete metamorphosis from those with complete metamorphosis which have 

 a true pupa. 



