February, '15] BISHOPP-DOYE-PARMAN: HOUSE FLY BIOLOGY 55 



depositions and interval between each, and notes on the effect of tem- 

 perature and humidity on the several stages. Some part of these are 

 discussed herein. The character of most of the biological points to 

 be determined necessitated the use of cages. It is well known that 

 conditions in cages are always more or less abnormal. This is true 

 in the tests herein reported, but we feel that by the methods employed 

 natural conchtions were closely simulated in most cases, thus reducing 

 this source of error to a minimum. The tables given herein include 

 representatives chosen from numerous experiments carried out. 



The experimental work was carried out at Dallas and Uvalde, Texas, 

 with supplementary field observations at Victoria, Texas, by Mr. J. D. 

 Mitchell. The detailed work at Dallas was carried out by W. E. Dove, 

 assisted by F. C. Bishopp, who planned and supervised all of the work, 

 and the experiments at Uvalde were carried out by D. C. Parman. 



Further experiments bearing on hibernation and certain other points 

 are now under way at Dallas and Uvalde. 



Copulation 



In a number of our preoviposition tests frequent observations were 

 made for copulation. Although continuous watch was not kept on 

 the flies it is thought that in some cases at least the first copulation 

 which took place was observed. The date when copulation was 

 observed in a number of experiments is given under Remarks" in 

 Table No. 1. The shortest period from emergence to copulation ob- 

 served was one day. In a number of instances two full days elapsed, 

 and in other cases copulation was first observed as late as the six- 

 teenth day after emergence. Of course mating may have taken place 

 unobserved before this. The time from the first observance of copu- 

 lation to the first deposition varies greatly. Frequently there appears 

 to be no direct relationship between the date of copulation and begin- 

 ning of deposition. We have observed a range of two to thirteen days 

 between the first copulation observed and deposition. 



It appears from our experiments that the time of development or 

 manifestation of the desire to mate is influenced to some extent at 

 least by the food of the adults. Thus in a test with two lots of flies, 

 one supplied with milk and horse manure and the other with partially 

 ripened peaches and horse manure, the former were first observed to 

 copulate four days after emergence and the latter sixteen days. In 

 no case was copulation observed among unfed adults. 



The process of copulation is always of considerable duration — ^last- 

 ing. from two or three to as long as fifteen minutes. During the act 

 the flies usually remain quiet, but if disturbed may fly about consid- 

 erably without becoming separated. Often prior to copulation and 



