ENTOMOLOGY. 377 



Sometimes, as with Grasshoppers, Locust, Aphides or Green 

 Fly, Plant Bugs, &c., the young in the first stage — whether 

 produced alive or hatched from the egg — much resembles the 

 parent, that is, has a distinct insect shape, of head with 

 horns, trunk or thorax, furnished with six legs, and abdomen ; 

 and differs mainly in size and in being wingless ; but^ whether 

 in this shape, or ivhat is known as gnih, maggot, or caterpillar, 

 or whatever kind of insect it mag belong to in tlds first stage, it 

 is scientifically a larva. 



Larva of Locust. 



In this larval stage the insect feeds voraciously and often 

 grows fast : the skin does not expand beyond certain limits, 

 and when this point is arrived at, the larva ceases feeding for 

 a while; the skin loosens, cracks, and is cast off by the 

 creature inside, which comes out in a fresh coat, sometimes 

 like the previous one, sometimes of a different colour or 

 differently marked. This operation is known as moulting, and 

 occurs from time to time till the larva has reached its full 

 growth. The duration of life in the first or larval state is 

 various ; in some instances it only extends over a week or 

 two ; in some (as with the Wireworm and caterpillar of the Goat 

 Moth) it lasts for a period of three, four, or five years. 



As far as observations go at present — that is to say, with 

 such kinds as have at present been observed — larvae are not 

 injured by an amount of cold much beyond what they are 

 commonly called on to bear in this country ; but they are 

 liable to injury from over supply of moisture, whether from 

 sudden rain in warm weather or from full flow of sap of 

 their food-plant, and in this point of their constitutions 

 we have a principle that may help much towards getting rid 

 of them. 



When the larva has reached its full growth it ceases feeding, 

 and (in the forms known as caterpihar, grub, or maggot) it 

 usually either goes down into the ground and forms a cell in 

 the earth, or spins a " cocoon " (that is, a web) round itself 

 of threads drawn from the lower lip (as in the well-known 

 Silkworm-cocoon), or in some way it makes or seeks a shelter 

 in which it changes from the state of larva to that of papa. 

 These various changes are not mere matters of curious 



