NO. 6 



CATERPILLAR AND BUTTERFLY — SNODGRASS 



cicada (fig. 2 A) as compared with the adult is more elongate and 

 cylindrical, with the front of the head strongly protruding and 

 rounded, but it has a special juvenile feature in the form of the front 

 legs. These legs are modified for burrowing during the underground 

 life of the nymph, and later (B) for climbing when it comes out of 

 the ground. The under surface of the femur is armed with strong 



Fig. 2. — Young nymph of the seventeen-year cicada, and change in the front 



leg from nymph (B) to adult (C). 



teeth, the tibia is toothed at its end, and the slender, undivided tarsus 

 is freely attached to its mesal surface. At the moult to the adult the 

 cuticle of these larval legs is cast off, and the adult leg (C) appears in 

 the typical mature form. The leg epidermis simply forms two kinds 

 of legs, one for the nymph, the other for the imago, but the nymphal 

 leg is a special adaptation for the nymph. 



It would be interesting to know when and how the young cicadas 

 first became adapted to underground life. With most insects of which 

 the young have a special habitat, the female lays her eggs where the 

 young will live. The female cicada, however, following the tradition 



