423 



(4.) Quality and Intensity of Light. 



(a). Intensity. As compared with diffused daylight, the length of 

 the pupal stage is longest in the dark. This is uniformly true in our 

 experiments. Isely and Ackerman ("23) have shown that light checks 

 egg-laying of the codling moth, and that temperatures above 62° after 

 sundown are essential to laying. 



(b). Color. A series of experiments on color gave inconsistent re- 

 sults. Red, blue, and green were less favorable, in all cases, than darkness 

 or Mazda lamp light through daylight glass. See Table Xlllg (p. 372). 



(5.) Food. 



It is a well-known fact that the larvae develop in picked apples more 

 quickly than in apples on the tree and in some varieties of apples than in 

 others, but no analysis of the cause has been made. (See Glenn '22.) 



(6.) Mechanical Stimuli and Number of Spinnings. 



Some investigators have maintained that the time to pupation is 

 increased by the number of spinnings and the large amount of mechanical 

 stimulation due to opening the cocoons several times for observations. 

 The results shown in Table XXVUI are on larvae that had spun one. two, 

 or three times in the fall, but were not disturbed in the spring. The sec- 

 ond item includes all that came through, while the first is only to May 20. 



Fig. 29. The average daily march of temperature and humidity 1915-17 

 at Olney. 



