EASTERN UNITED STATES. 19 



THE LAKVA. 



The larva, or caterpillar, is elongated or somewhat 

 worm-like, usually plainly separable into thirteen joints 

 or segments, the first of which is the head. Joints two, 

 three, and four have each a pair of short legs, the 

 rudiments of the legs of the perfect butterfly. Joints 

 seven, eight, nine, ten, and thirteen have each a pair of 

 membranous legs, the end of each 

 armed with a circle of minute hooks, 

 as seen in Fig. 2. By means of , ^ 



these hooks the larva is enabled ' to 

 grasp firmly any object which is not 

 too smooth, as the surface of glass. 



In this case the larva first spins a From larva of v. AH- 



r> MI J.T. i i P a - a > P role S' X 4 /4 ; &> 



covering of silk over the glass, and circlet of hooks at end of 



then walks over it easily. These legs pn>ieg, X ; c, one of the 



hooks, X 12. 



are called prop-legs, or, as it is more 

 often abbreviated, prolegs. These disappear at the close 

 of the larval period, when the larva changes to a chrys- 

 alis. 



On each side of the body are nine oval stigmata, or 

 breathing-pores, often called spiracles. These are situ- 

 ated in joints two and five to twelve inclusive. These 

 stigmata open into a series of air-tubes which ramify 

 through the system, each stigma leading to a single trunk 

 of the system. Close to the origin of this trunk a large 

 air-canal runs along each side of the body, connecting 

 all the trunks of one side. Joints three and four, having 

 no stigmata, receive their branches of the system of air- 

 passages from this trunk. Like the air-passages in the 

 lungs of the vertebrate animals, these tracheae continue to 



