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tion, which induces a high degree of temperature, often of 90° and over, 

 in cold weather many degrees higher than in the surrounding atmos- 

 phere. Under certain conditions this temperature may be maintained 

 the 3 T ear round, and it is therefore necessary to know the minimum 

 periods before we can determine or even estimate the number of gener- 

 ations that may be developed in a year. 



The following account of my experiments is given: 



PERIOD FR03I EGG TO ADULT. 



Experiment Xo. 1. — Newly hatched larva? from eggs deposited April 

 18 were placed in corn meal. June 2 one had transformed to pupa, the 

 moth issuing June 9. Two more moths appeared the day following, 

 a total of fifty-two days as the life cycle for this period, which happened 

 to be cooler than normal for this latitude. 



Experiment Xo. 2. — Moths placed in corn meal April 30 produced the 

 first members of another brood June 11, or in forty -six days. Weather 

 normal. 



Experiment Xo. 3. — Adults confined with corn meal at midday, June 

 10, 1896, and four moths of the new brood were found to have issued 

 July 20. The exact date of issuance was not ascertained owing to the 

 writer's absence from the office Sunday, but from their appearance they 

 had bred either during the night of July 18 or 19, and the duration of 

 the period was between thirty-eight and thirty-nine days. The tempera- 

 ture for this period, although not unseasonably cool, was not as warm as 

 in previous years, the indoor temperature not ranging above 82° F. 

 except on three or four days. 



Experiment Xo. 4. — Moths placed in corn meal June 22. Two full- 

 grown larva? left the meal July 20 to seek a place for transformation. 

 and the following day about 20 followed suit. Three moths issued dur- 

 ing the night of July 30, being found early on the morning of the 31st, 

 and giving nearly the same period from the egg to moth as in the pre- 

 ceding experiment, thirty-eight days. 



INCUBATIOX. 



An experiment to determine the minimum period of incubation began 

 on the afternoon of April 18, when a few moths were placed singly in 

 vials for the purpose. These were examined at 6.30 p. m. and at 11 p. m. 

 and a large batch of eggs found to have been laid in one of the vials 

 in the interim. A considerable proportion were found to have hatched 

 early in the afternoon of April 23, or about four and one-half days 

 from the time of deposition. Weather the first day very hot, the sec- 

 ond quite cool, the remaining time seasonable, the indoor temperature 

 ranging from 91° to 66° F. 



In colder weather the egg state may last as long as two weeks. In 

 Mr. Johnson's experience it lasted from seven to nine and one-half days, 

 the eggs having been deposited in April, August, and October. 



