Borboridae 435 



viz., L. jrontenalis, Borboms equinus, and Sphaerocerus subsultans, and 

 they are probably susceptible to similar handling. 



These small flies of the genus Leptocera are numerous about dung, 

 especially sheep dung, during apparently the whole of the summer 

 season. They are easily captured in the field with a sweeping net, or 

 at windows of barns, where they gather in large numbers at the top of 

 the window panes, and may be collected by taking advantage of their 

 positive phototropism. 



Sexes are easily determined with the aid of a hand lens or dissecting 

 microscope. Occasionally the anal plates of the female are not visible. 

 Slight pressure on the abdomen of an etherized individual with a 

 camel's hair brush will force the anal plates beyond the edge of the last 

 segment, if the individual be a female. 



In breeding the flies we have used sheep dung, although it appears 

 probable that other food materials ("decomposing organic matter," 

 Williston, 1908) may be used. Our method was to collect sheep pellets, 

 preferably fresh samples, which were first crushed in water and then 

 boiled. This procedure resulted in sterilizing the dung to a large extent 

 as well as permitting it to be brought to a certain desirable consistency. 

 After cooling, pint milk bottles were about % filled with the cooked 

 dung and were plugged with cotton, after which newly emerged flies 

 were transferred to them. Flies for breeding were allowed to remain 

 in the bottles 7 or 8 days, by which time the females have laid most of 

 their eggs. 



It seems to us possible that Leptocera spp. as representatives of a fly 

 family, the Borboridae, which are wide-spread if not cosmopolitan in 

 nature upon the dung of mammalia (Howard, 1900), with their small 

 convenient size, short life cycle, easily satisfied food conditions, capabil- 

 ity of continuing their life histories in the now familiar laboratory milk 

 bottle, and apparent hardihood in withstanding repeated etherization, 

 combine a group of characteristics which might well make them utiliz- 

 able material for investigations in insect physiology, genetics, etc. It 

 may be mentioned in addition that members of the Borboridae, both 

 larvae and adults, are reported as hosts of herpetomonads (Patton and 

 Cragg, 1913). 



Reference 



For the culture of Borboridae see also p. 412. 



Bibliography 



Howard, L. O. 1900. A contribution to the study of the insect fauna of human 



excrement. Proc. Wash. Acad. Set. 2:541. 

 Patton, W. S., and Cragg, F. W. 1913. A Textbook of Medical Entomology. P. 311. 

 Williston, S. 1908. North American Diptera, 3rd edit. P. 316. 



M. E. D. 



