PREOVIPOSITION PERIOD OF THE HOUSE FLY. 13 



SUMMARY. 



From the experiments reported in this paper it is seen that the 

 shortest record for the preoviposition period was one of about 2\ 

 days and the longest, one of 23 days, with most of the records falling 

 on the fourth, fifth, sixth, ninth, twelfth, and fourteenth days after 

 emergence. 



It is shown that the temperature has a very decided influence on 

 the length of the period. 



Other factors influencing this period are humidity, the kind and 

 quality of the food of the adults, and the kind and quality of the 

 larval food with its resulting effect on the size and physiological con- 

 dition of the adults. In the experiments with isolated pairs of flies 

 very few results were obtained, which suggests that the association 

 of a number of females in the process of egg laying is the normal 

 habit and that isolation has an inhibiting effect. 



Copulations were observed as early as the first day after emergence 

 and as late as the forty-seventh day. No copulations have been 

 noted when the air temperature has been below 55° F. 



The maximum record for longevity was 70 days, and the minimum 

 was one day or less. The average of the records of some 3,000 flies 

 was slightly over 19 days. 



LITERATURE CITED. 



Bishopp, F. C, Dove, W. E., and Parman, D. C. 



1915. Notes on certain points of economic importance in the biology of the house 

 fly. In Jour. Econ. Ent., v. 8, No. 1, p. 54-71. 



BOGDANOW, E. A. 



1903. Zehn Generationen der Fliegen (Musca domestica) in veranderten Lebens- 

 bedingungen. In Allg. Ztschr. Ent., Bd. 8, p. 265-267. 

 Griffith, A. 



1908. Life history of house flies. In Public Health, London, v. 21, p. 122-127. 

 Hewitt, C. G. 



1910. The house fly. 195 p., 22 pi. The University Press, Manchester, England. 

 Howard, L. O. 



1911. The house fly, disease carrier. 312 p., 39 fig. Stokes and Co., New York. 

 Peairs, L. M. 



1914. The relation of temperature to insect development. In Jour. Econ. Ent., 

 v. 7, No. 2, p. 174-179. 



