4 AN INTRODUCTION TO ENTOMOLOGY. 



spermatozoa pass into the egg, and thus fertilize it. Many of the 

 interesting exhibitions of instinctive powers which I have described 

 in the following pages are connected with the care of their eggs 

 by insects. 



The Larva. — The larva is the second of the four principal stages 

 in the life of an insect. It is the stage in which 

 an insect emerges from the egg. Familiar ex- 

 amples of larvae are caterpillars, maggots, grubs, 



. \ -r • i • i i i i Fig. 5. — Larva of Diatricea. 



etC. (rig. *,). It IS during the larval State that (From the Author's Re- 

 , r , • i i port for 1879.) 



the growth of the insect is made ; and conse- 

 quently in this stage nearly all the moults are undergone. The 

 moults subsequent to this period are simply those made when the 

 insect changes from one stage to another. 



Nearly all of the creatures commonly known as worms are not 

 true worms, but are the larvae of insects. Away from the sea-shore 

 but few worms are known to other than zoologists ; these are 

 earth-worms, leeches, hair-worms, and the various species parasitic 

 in the bodies of higher animals. The many worm-like animals 

 found feeding upon the tissues of plants, as tomato-worms, apple 

 worms, etc., are the larvae of insects. Other larvae of insects are 

 predaceous or parasitic. 



The Piipa. — The pupa is the third of the four stages in the life of 

 ^^-s^ _ an insect. In this stage the insect is 



£k usually quiescent. But a few pupae, 

 » as those of mosquitoes, are active. 

 ■. : -*f The change from the larva to the 

 pupa state is made by moulting the 

 skin of the fully grown larva. In the 



Fig. 6. — Pupa of Platysamia. ,11 1 • r ,1 1 ■, 



pupa the legs and wings or the adult 

 are represented in a rudimentary state. In the pupae of butterflies and 

 moths these organs are closely soldered to the breast of the insect 

 (Fig. 6), while in the pupae of bees, wasps, and beetles they are 

 free. 



Chrysalis. — The term chrysalis is applied to the pupa of a but- 

 terfly. This name was suggested by the bright, metallic spots 

 with which the pupae of certain butterflies are marked. Two forms 

 of this word are in use: chrysalis,//, chrysalides; and chrysalid,//. 

 chrysalids. 



The Cocoon. — Many larvae, as those of moths, when fully grown, 

 and before they change to pupae, spin about the body a silken case, 



