INSECTS 



Bulletin, The Periodical Cicada, published by the United 

 States Bureau of Entomology in 1907. Doctor Marlatt 

 describes six immature stages of the periodical cicada 

 between the egg and the adult. 



The young cicada that first enters the ground is a 

 minute, soft-bodied, pale-skinned creature about a twelfth 

 of an inch in length (Fig. 126). The body is cylindrical 

 and is supported on two pairs of legs, the front legs being 

 the digging organs; the somewhat elongate head bears a 

 pair of small dark eyes and two slender, jointed antennae. 

 At no stage has the cicada jaws like those of the grass- 

 hopper; it is a sucking insect, related to the aphids, and 

 is provided with a beak arising from the under surface 

 of the head, but when not in use the beak is turned back- 

 ward between the bases of the front legs. Throughout 

 the period of its underground life, the cicada subsists 

 on the sap of roots. 



During more than a year the young cicada retains ap- 

 proximately the form it has at hatching, though the body 

 changes somewhat in shape, principally by an increase 

 in the size of the abdomen (Fig. 113). According to 

 Doctor Marlatt, a nymph of the seventeen-year race first 



sheds its skin, or molts, some- 

 time during the first two or 

 three months of the second 

 year of its life. 



In its second stage it be- 

 comes a little larger and is 

 marked by a change in the 

 structure of the front legs, 

 the terminal foot part of 

 each being reduced to a 

 mere spur and the fourth 

 section being developed into 

 a strong, sharp-pointed pick which forms a more efficient 

 organ for digging. The second stage lasts nearly two 

 years; then the creature molts again and enters its third 



I 186 I 



Fig. 113. Nymph of the periodi- 

 cal cicada in the first stage, about 

 18 months old, enlarged 15 times. 

 (From Marlatt) 



