24 



On one occasion the deposition of a larva by a female of G. morsitans, 

 form submorsitans , under natural conditions, at Larabanga, in the 

 Northern Territories of the Gold Coast, was witnessed by Dr. J. J. 

 Simpson (144). According to the author in question, the insect 

 " took up her position on the under side of the trunk [of a felled tree], 

 about an inch from the ground, and thence let the larva drop. Within 

 five minutes the larva had penetrated the soil and had disappeared." 



" According to Stuhlmann's observations on female specimens of 

 G. brevipalpis, kept by him in captivity at Amani, German East Africa 

 [Tanganyika Territory], the act of birth, though occasionally lasting 

 for a quarter of an hour or more, generally takes place very quickly " 

 (Austen). 



Dr. B. Moiser (100), writing of the behaviour of captive specimens of 

 G. tachinoides in Bornu Province, Northern Nigeria, says : " While 

 watching a female at rest on the floor of the bottle, I noticed a violent 

 contraction of the abdomen, starting from the thorax, and immediately 

 a white larva was extruded. The fly remained on the spot for a few 

 minutes, and then flew away." 



DURATION OF THE PERIOD OF GESTATION. " Observations show that, 

 under normal conditions as regards temperature and humidity, the 

 extrusion of larvae takes place at intervals of from about eight to 

 eleven days " (Austen). 



The foregoing, however, scarcely holds good with regard to G. 

 morsitans in captivity, for Kinghorn (79) states that : " Considerable 

 irregularity has been displayed by the females in extruding larvae. 

 After the first one had been born, many of them did not produce a 

 second for a considerable length of time, and this may have been 

 dependent upon the meteorological conditions to some extent. A 

 number of the flies, however, have produced a second larva at an 

 interval of from 14 to 15 days after the birth of the first, and this 

 may be taken to represent the normal period of gestation under the 

 laboratory conditions." 



According to Croveri (35), in Italian Somaliland females of G. 

 pallidipes, presumably under laboratory conditions, deposit from seven 

 to ten larvae at an average interval of ten to eleven days. 



Dr. Roubaud (1190), from his observations on G. tachinoides in cap- 

 tivity in Dahomey, states that, at a temperature of 25 C.(77 F.), 

 the larvae of this species are deposited at intervals of eight days. 

 In the case of females of G. longipalpis, likewise observed by Dr. 

 Roubaud, the extrusion of larvae at the same temperature occurred 

 at intervals of about ten days. 



Reverting to Austen's account (already referred to) of Stuhlmann's 

 observations on the breeding of G. brevipalpis at Amani, Tanganyika 

 Territory, we read : " The larvae produced by a female kept at a 

 temperature of from 23 to 25 C. (73-4 to 77 F.) were extruded at 

 intervals, which varied with the temperature from ten to twenty-two 

 days, the mean interval being about twelve days ; thus in three months 

 and a half a single female gave birth to eight larvae, two of which, 

 however, were not viable. Throughout the period during which 

 females of G. brevipalpis were kept at Amani (i.e., from the beginning 

 of September, 1905, until the middle of May, 1906), the extrusion of 

 larvae proceeded uninterruptedly at approximately regular intervals, 

 though these were somewhat shorter in the hot than in the cold weather. 

 Stuhlmann consequently sees no reason why in nature the production 



