CODLING MOTH IN COLORADO. 83 



sycophanta L., which has been instrumental in partially reducing 

 the number of brown-tail moth and gipsy moth larvae as well as other 

 lepidopterous larvse of the New England States. Over 1,000 of 

 these beetles were released in June, 1915, but none were recovered 

 after their distribution. 



PARASITIC ENEMIES. 



The parasitic enemies of the codling moth in the Grand Valley 

 play a very unimportant role in its control, although in one instance 

 an egg parasite, Trichogramma minutum Riley, was found quite 

 abundant in the field in a small pear orchard. Some of the foliage 

 surrounding the fruit was pulled at random and then was exam- 

 ined for eggs. Out of the first 100 eggs found, 15 were parasitized 

 by this insect. As many as three of these parasites were found 

 developing within one codling moth egg, while quite frequently 

 two of the parasites inhabited the same egg. 



Another parasite, Dibrachys clisiocam-pae Fitch, was found to 

 attack the codling-moth larva and continue to feed upon the host 

 after it had transformed to the pupa stage. 



The parasite Arthrolytus apatelae Ashmead was also reared from 

 material collected in the field. 



In general, the occurrence of parasitism was so infrequent that 

 little good was accomplished by this class of natural enemies. 



MISCELLANEOUS STUDIES. 



EFFECT OF COOL TEMPERATURES ON EMERGENCE OF MOTHS OF THE 



SPRING BROOD. 



In laboratory cellar. — As a means of studying the influence of cool 

 temperatures upon the emergence of moths of the spring brood, a 

 number of wintering larvse were placed in the cellar of the lab- 

 oratory. This cellar was of the usual type, having stone walls and 

 a cement floor, and was moderately dry. The temperature and 

 atmospheric conditions within would compare somewhat with the 

 fruit cellars or caves in which fruit is sometimes stored in the 

 Grand Valley. The cage containing the insects was examined daily 

 and the results of the observations will be found in Table LVIII. 



A study of this table will show that the first moth, under cellar 

 conditions, did not emerge until May 30, or 18 days after the first 

 adult appeared in the outdoor insectary. It is noteworthy that the 

 last emergence of moths in the cellar cage and the insectary cages 

 occurred the same day, June 29. From these observations it would 

 appear that the lower temperature in the cellar had a retarding 

 influence in the development of the insect for some time, but that 

 after the insects had been subjected to a sufficient accumulation of 

 effective temperatures, their complete transformations to the adult 

 stage were not long delayed. 



