July 2, 1917 Life History of Plutella maculipennis 7 



Table IV. — Rearing records of Plutella maculipennis at Phoenix, Ariz., in igi4 



Jan. 20-21 First adults issued. 



Jan. 23 First eggs deposited. 



Feb. 5 First eggs hatched. 



Feb. 17 First cocoons formed. 



Feb. 19 First lar\'se pupated. 



Mar. 2 First adults issued. 



As noted in Table IV the stages are as follows: 



Days. 



Egg stage 13 



Larva stage 14 



Pupa stage 1 1 



Total duration 38 



The larvae reared at Rocky Ford during May lived as leaf-miners for 

 the first two or three days of their existence, whereas those reared at 

 Phoenix during February lived in mines for four days. At Rocky Ford 

 during October and at Phoenix during January and February many of 

 the older larvae changed to a dark, dull-green color and were marked 

 wnth reddish spots. The mining habit and the changes in coloration 

 occurred with lar^^ae in the field as well as those confined in cages and 

 were obviously induced by low temperature. 



EGG-LAYING RECORDS 



Egg-laying records were obtained at Rocky Ford by confining single 

 pairs of moths, immediately after they issued, in large jelly glasses. The 

 moths were fed diluted honey or the nectar of watercress. A cabbage 

 leaf was placed in each cage daily, and upon these leaves the eggs were 

 deposited. The eggs were counted daily and destroyed. The number 

 of eggs deposited by nine females which issued during July and August 

 were 287, 116, 413, 202, 237, 427, 282, 168, and 451, respectively, or an 

 average of 287 eggs per female. 



A detailed record of the female of one of these pairs of moths, which 

 issued on August 16, is given in Table V. 



Table V. — Egg-laying record of a single female of Plutella m,aculipennis at Rocky Ford, 



Colo., in igi6 



Eggs deposited. 



Aug. 17 26 



Aug. 18 78 



Aug. 19 69 



Aug. 20 43 



Aug. 21 32 



Aug. 22 23 



Aug. 23 " 



Total. 282 



