58 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



after copulation has taken place the sexes fly together or the males 

 temporarily alight on the females. - This appears to be in the nature 

 of courting. When not ready to accept the attentions of the male the 

 female protects herself largely with her posterior legs which are kept 

 near the tip of her abdomen. 



The Preoviposition Period 



In 1907, Dr. C. Gordon Hewitt, working in England, found that a 

 period of fourteen days elapsed between the emergence of adults from 

 puparia and the first egg deposition by them.^ In experiments at 

 Hove, England, Dr. A. Griffith determined the preoviposition period 

 to be ten days.^ Professor A. Berlese has also published results of 

 observations made by him on the reduction of numbers of the house 

 fly in S. Vincenzo, Italy, due to the poisoning of adult flies incidental to 

 the sprajdng of olive trees for the control of the olive fly.^ Professor 

 Berlese also secured satisfactory results in controlling the insect by 

 sprajdng vegetation, manure and garbage with poisoned sweets. 



In order to determine the preoviposition period a series of experi- 

 ments were conducted at Dallas and Uvalde. In these tests cages of 

 various sizes from one foot cubes to cages ten feet square by six feet 

 high, were utilized; the latter appeared to furnish almost ideal condi- 

 tions. These were placed in partial or complete shade or in open 

 sunshine. Freshly emerged flies were used in numbers varying from 

 a pair to several hundred. Different kinds of food were supplied and 

 the breeding media were also varied. A few of the experiments are 

 summarized in table 1. 



It Tvdll be seen in Table No. 1 that the shortest preoviposition period 

 observed at Dallas was four days and the longest twenty days. The 

 mean temperatures during these periods were 87.5° F. and 68.1° F., 

 respectively. The usual preoviposition period during the summer at 

 Dallas appears to range from four to about nine days. While in 

 autumn it is probably never shorter than ten days. Although it is 

 certain that temperature has much to do with the development of the 

 ova in flies, it is also evident that the food supply, both abundance and 

 qualitj^, is an im^portant factor. This is well illustrated in the lot of 

 flies which emerge between August 19, 5.30 p. m. and August 20, 9.30 

 a. m. and were given nothing but cut peaches for food and breeding 

 medium as compared with, flies which emerged between August 20, 



^ 1910. Hewitt, C. Gordon. The house fly; a study of its structure, develop- 

 ment, bionomics, and economy, p. 64. 



2 1908. Griffith, A. The life history of house flies. Public Health, Vol. XXI, 

 pp. 122-127. 



2 1913. Berlese, A. La distruzione della Mosca domestica. Redia, Vol. VIII, 

 Pt. 2, pp. 462-472, 4 figs. 



