258 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



mesothorax and the metathorax show prominently through 

 the egg shell as 4 black spots 20 hours before the egg is ready 

 to hatch. When the larva is ready to emerge, it makes 2 longi- 

 tudinal slits near, but not quite at, the anterior end of the egg. 

 The only chitinized portions of the cuticula at the time of the 

 emergence are the dorsal halves of the lateral tubercles of the 

 last 2 thoracic segments, and the writer believes that they are 

 the instruments used in rupturing the egg shell. These tubercles 

 show up very prominently in a newly hatched larva, as the chit- 

 inized portions are jet black, while all the rest of the body is 

 bright yellow. The explanation offered above would account 

 for this peculiar appearance, which is characteristic of the newly 

 hatched larvae of all of the Alticini which the writer has 

 observed. 



The thorax is arched out through one of these longitudinal 

 slits, sometimes the right one, sometimes the left. The presence 

 of the second slit doubtless lessens the rigidity of the egg shell, 

 and makes it yield more readily to the efforts of the larva in the 

 process of hatching. This is accomplished merely by the regu- 

 lar contraction and relaxation of the body muscles. The meson- 

 otum is the first part to protrude through the opening, then 

 the metanotum and the pronotum, giving the larva a sort of 

 hunch-backed appearance. After a long, hard process of similar, 

 slow, regular, alternate contraction and relaxation of the body 

 muscles, the larva finally succeeds in withdrawing its head 

 from the opening. In 5 minutes, or even less time, after the 

 head is free, the legs are drawn out, all almost simultaneously, 

 and the larva walks out of the shell. 



This process was observed several times. The time required from 

 the appearance of the first break in the shell until the larva was entirely 

 free varied from 28 to 39 minutes; it usually occupied about 30. The 

 following example is cited as a typical case: 10.05 first break in the egg 

 shell; 10.10 second break in the egg shell; 10.20 metanotum and mesono- 

 tum exposed; 10.25 pronotum exposed; 10.31 head free; 10.33 prothoracic 

 legs drawn out; the other legs freed almost simultaneously; 10.35 larva 

 entirely out of the shell. 



THE LARVA. 



Description of the full grown larva. Head, thorax, and 

 abdomen distinct ; abdomen composed of 10 segments ; prono- 

 tum and dorsum of 9th abdominal segment strongly chitinized 



