PROCEEDINGS, 1918 43 



attain full growth in an average of 19.5 days, the actual time 

 ranging from 18 to 23 days. They then enter the ground, 

 form an earthen cocoon and pupate, this period lasting from 

 20 to 25 days, with the individuals kept under observation. 

 Upon emerging from the ground, the adult begins feeding and 

 continues to do so for several weeks before it again enters the 

 ground where it hibernates. The exact length of time spent 

 in this stage has not been determined. Records of the life his- 

 tory will be found in the accompanying table. 



The Egg. 



The eggs are deposited in irregular masses, varying from 

 seven to twenty on the under side of the leaves of alder (Alnus 

 glutinosa) They are contiguous and are attached to the leaf 

 at their base. 



Description. Cylindrical, broadly rounded at base, widest 

 about the middle of its length and tapering slightly towards 

 the apex. 



Chorion, delicate, semi-transparent and covered with min- 

 ute papilli. 



Color, very pale, delicate, lemon yellow. 



Length, 1.67 m. m.-1.70 m. m. Greatest width .756 m. m.- 

 .783 m. m. 



The Larva. 



The larva eats a circular hole through the cap of the egg 

 and, upon emerging, feeds first upon its own shell as described 

 for the preceding species, after which it attacks the leaf. It is 

 a heavy feeder, but when small only eats the fleshy parts of the 

 leaf, and even when fully grown seldom eats the midrib or larg- 

 er veins. While small, they are gregarious, but as they be- 

 come larger they distribute themselves over the plant and are 

 seldom found in larger numbers than two or three on a leaf. 



Description of Stages. 



First Instar. General appearance short and thick, very, 

 strongly convex dorsally, widest at second abdominal segment 

 tapering gradually towards the head and somewhat abruptly 

 towards the posterior end, which is curved downward. 

 Lengthwise of the body are four rows of small tubercles. The 

 dorsal row wanting on the prothorax and mesothorax; the sub- 



