336 



Marvels of the Universe 



plant and through which it sucks up the sap. The Cicada grub feeds in this \va\- upon the roots 

 of various plants and trees ; it does not remain fixed in any one spot, but burrows here and there 

 in the earth, tapping the roots first in one place, then in another. In its wanderings it often pene- 

 trates a considerable distance from the surface ; ten feet, even twenty feet down thev have been 

 found. The Cicada passes by far the greatest portion of its life in the earth in this manner ; our 

 British species Hves three or four years in this condition, while the common species of the Eastern 

 States of North America spends sixteen \'ears as a larva, successive broods thus appearing every 

 seventeen years. Although this is the average length of life of this species in the Northern States, 



. in the Southern States it becomes reduced to 



thirteen vears, and as there are naturally inter- 

 mediate stages, it must not be supposed that 

 the insect is seen in its perfect state only once 

 every seventeen j^ears. In one district or 

 another it turns up every year, but in any 

 given district the numbers in the intermediate 

 years are quite insignificant, whereas in the 

 year when a brood is due they come in their 

 millions and there is no escaping from them. 



It may be wondered how a soft-bodied 

 creature like a Cicada larva can burrow in 

 hard dry earth, even though provided with 

 fairly powerful legs. As a matter of fact, it 

 moistens the earth before attacking it, making 

 use of the supply of sap in the tree-roots for 

 this purpose. Digging its proboscis into a 

 root, it gorges itself with the sap, proceeds to 

 the working face of its burrow, which may be 

 some little distance away, and voids the super- 

 fluous hquid on to the hard earth, which is 

 then comparatively easily removed. The 

 same tactics are familiar to all in the case of 

 its little relative, the Frog-hopper, or Cuckoo- 

 spit Insect, whose larva in a similar manner 

 pierces the stems of our garden plants, and 

 with the sap, after it has passed through its 

 alimentary tract, forms the well-known froth, 

 or cuckoo-spit, that is so conspicuous upon 

 the plants. 



When full grown the larva casts its skin once more ; but instead of being soft and white, it 

 is now covered with a firm, hard brown skin, though still very similar in form. This condition is 

 almost equivalent to the chrysalis of a butterfly or moth, but there is the very important 

 difference that the Cicada nymph, as it is called, can still feed and still has the full use of its limbs. 

 This state lasts only a few days, but in that time the creature makes careful preparations for its 

 forthcoming brief period of existence in the air and sunshine. Coming to within a few inches of 

 the surface, it selects a suitable root as a resei'voir from which it may draw supplies of sap for future 

 operations ; it then proceeds to drive a tunnel vertically upwards to the surface of the ground, returning 

 from time to time to the root at the bottom for liquid to moisten the earth as the work progresses. The 

 damp earth it works up into a paste or mortar, with which it lines its tunnel. Some American 

 species having reached the surface, continue the tunnel as a round, hollow tower some inches high ; 



l-holo io] 



CICADA EMERGED. 



The newlv-emerged Cicada, having sufficiently 

 on the empty chrysalis-skin basking in the si 

 taking its first flight. (Natural size.) 



[/*. //. Fuhre. 



hardened, sits 

 nshine before 



