180 ANIMAL METAMORPHOSIS. 



or small pieces of coral being utilised by them, when confined in 

 an aquarium, thus forming habitations most beautiful in 

 appearance. 



The time taken by these transformations varies much in dif- 

 ferent insects. Most butterflies pass through their larval stage in 

 about three weeks, and, assuming the crysalis form in autumn, 

 pass the winter in this safe retreat, emerging from it in the first 

 warm days of the following spring ; but the tiger-moth lays its 

 eggs in autumn, the caterpillars are hatched the same month, but 

 after a time retire to winter quarters, re-appearing the following 

 spring, and then going through their subsequent stages of develop- 

 ment. Others, as the Ephemerae, live for nearly two years at the 

 bottom of the pond in which they are hatched, till at last they 

 acquire wings and exist only for a few hours. 



The female Cockchafer, about the end of April, digs a hole in 

 a well-cultivated field, in which she lays her eggs (about thirty in 

 number). In a month, the small whitish larvce, which feed on the 

 rootlets of plants, are hatched ; as the cold comes on, they dig 

 deeper, and pass the winter in clusters ; when spring arrives, they 

 are larger and more ravenous, and are most destructive to plants 

 and even trees. This subterranean life goes on for three years, at 

 the end of which time each larva makes a sort of chamber of clay, 

 and is transformed into a nymph or pupa, remaining torpid till the 

 end of February, when it emerges from its case ; at first, it is soft 

 and uncoloured, and remains underground till about the end of 

 April, when its skin has become hard and strong, and for the two 

 short remaining months of its life it flies from tree to tree, feeding 

 on the leaves of the oaks, beeches, and maples. 



The x^nt-lion — which, in its perfect stage of existence, is a four- 

 winged insect, resembling the dragon-fly — passes the first two 

 years of its life in the larval state, burying itself in a conical pit, 

 which it excavates in fine, loose sand ; from the bottom 

 jjrotrude only its formidable jaws, ready to seize any insects, 

 especially ants, which approach too near to the margin of its 

 pitfall and slide down its slippery walls, the sand giving way 

 beneath their feet. AMien about to change into a pupa, it con- 

 structs a coccoon of sand, which it lines with a beautiful tapestry 

 of silk. Having remained in this coccoon about three weeks, it 



