28 



Table I. — Duration of egg atage of codling moth — Continued. 



Date laid. 



1902. 

 Aug. 27 



Aug. 28 



Do 



Aug. 29 



CORDLEY 



May 7 



Do 



Number i Date \ Number 

 laid. hatched, hatched. 



187 



1902. 

 Sept. 5 

 Sept. 6 

 Sept. 8 

 Sept. 8 

 Sept. 9 

 Sept. 12 

 Sept. 15 

 Sept. 9 

 Sept. 6 

 Sept. 1.5 

 Sept. 8 

 Sept. 9 

 Sept. 12 



June 1 

 May 12 



164 



Period of 

 incuba- 

 tion. 



Days. 



Total ef- 

 fective 

 tempera- 

 ture. 



F. 

 278 

 307 

 360 

 269 

 295 

 364 

 428 

 216 

 269 

 428 

 2.54 

 286 

 349 



298 

 285 



Average 

 effective 

 tempera- 

 ture. 



The results under normal orchard temperature give the length of 

 the stage from 9 to 18 days, with a weighted average of 11 days. This 

 average is longer than has been given by other authors, which may 

 be accounted for by the fact that it is the usual custom to keep the 

 eggs in laboratories rather than under normal orchard conditions, and 

 that the times of the laying of the eggs were estimated. 



HATCHING OF THE EGG. 



Recent authors are quite well agreed as to how the larva breaks or 

 eats its way out of the shell. Professor Slingerland was most proba- 

 bly the tirst to observe this operation. He states that the larva came 

 out of the Qgg near the edge at one end through an irregular crack in 

 the shell. (PI. Ill, es.) The writer has never observed this emer- 

 gence, but upon examining man}^ Qgg shells an iri'egular crack was 

 always found which was almost always at one end of the shell. 



CHANGES DURING INCUBATION. 



When laid the Qgg is of a translucent pearly color, often with a 

 yellowish tinge. Observations upon 88 eggs show that from 2 to 5 

 days with a weighted average of 3 days after being laid a red ring 

 makes its appearance. This ring appears gradually at lirst whitish, 

 then yellowish, and later quite a brilliant red. By observations upon 

 56 eggs it was found that in from 7 to 10 days, with a weighted aver- 

 age of 8.1: da3^s after ])oing laid, the egg loses the ring and in its place 

 the larva can be seen, the " black spot," which consists of the head 

 and cervical shield, being the most conspicuous part. 



Professor Gillette states that his assistant, Mr. E. P. Taylor, found 

 the red ring to appear in from 2 to 3 days after laying and the black 



