166 Maine Agricultural Experiment Station. 1918. 



cles and nodules lie very close together, and give the larva a 

 dark aspect; late in the instar, the general color of the larva 

 is much lighter, since the integument is stretched, the nodules 

 farther apart, and the tubercles smaller in proportion to the 

 body surface. 



Such a series of color changes is very characteristic of all 

 of the species treated in this bulletin, and indeed of all flea- 

 beetles which the writer has studied. They are either white or 

 yellow after a molt (according to the color of the fat-body), 

 as there is no pigment in the cuticula ; they rapidly become 

 darker, and the darkness is at a maximum a few hours after 

 the molt; then they gradually become lighter throughout the 

 instar, and the coloration of the early and late part of the same 

 instar is frequently quite different. 



Hatching. When the larva is ready to emerge from the 

 egg, the shell splits near, but not quite at, the anterior end, a 

 very tiny slit first appearing. Soon a second slit appears parallel 

 to the first. From one or the other of the openings thus formed 

 is pushed out the mesothorax. Gradually the whole thorax is 

 arched out of this opening, first the mesothorax and later the 

 prothorax and metathorax. c In about 10 minutes from the time 

 the crack first appears, the fused tubercles v-vii-viii of the two 

 posterior thoracic segments are exposed, and the larva has a 

 decidedly hunch-backed appearance. After a hard struggle of 

 about 10 minutes longer, the head also is withdrawn through 

 this opening, and the legs almost immediately after. The legs 

 are but little used for they are still soft and weak. Nearly all 

 of the hatching process is accomplished simply bv alternately 

 contracting and relaxing the body muscles. In about 30 minutes 

 the larva is two-thirds out of the shell, but it is usually another 

 half hour before it finally crawls out completely. 



Coloration after hatching. When the larva emerges from 

 the egg shell, it is entirely grayish white, including head, legsJ 

 and shields, except for the 4 black spots on the thorax. These 

 spots are formed by the fused tubercle v-vii-viii on each side of 

 the mesothorax and metathorax, which are the only pigmented 

 portions of the , cuticula at the time of hatching. The larva 

 becomes fully colored in about 2 hours. 



