BIONOMICS OF TSETSE, ETC., IN THE GOLD COAST. 197 



a temperature of 109° and 112° F. For this reason, when cattle, horses, and other 

 animals have to be transferred from one place to another, this should be done if 

 possible during the night. 



II. Glossina palpalis var. pallida, var. nov. 



One of the greatest difficulties I experienced in identifying tsetse was in regard to a 

 small variety of G. palpalis. This variety was first found by me in the upper reaches 

 of the River Gambia. At that time (1911) I reserved an opinion as to its identity. 

 Subsequently, Dr. Macfie found them in large numbers in the Ilorin province of 

 Northern Nigeria. In his report on that province (Bull. Ent. Research, iv, p. 13) 

 he makes some observations on the characteristics of the variety and gives an excellent 

 illustration of it (Plate vii). At Yapi I found very few typical G. palpalis but 

 large numbers of this variety. It is almost identical in size and markings with 

 G. tachinoides, but an examination of the genital armature of a very large number 

 leaves one in no doubt as to its identity with G. palpalis. When females are gorged 

 with blood, however, or have become discoloured, it is almost impossible to dis- 

 tinguish them.* The variety is so distinct in size and markings from G. palpalis, 

 which prior to Newstead's study of the genital armature were the only specific 

 characters, that I think it advisable to give some distinctive name, such as var. 

 pallida to this race. It is especially worthy of note that no intermediate forms exist 

 between this variety and typical G. palpalis. 



III. Food of Glossina. 



The question as to whether tsetse are entirely dependent on blood for their food 

 supply, and if so, what blood is most acceptable, calls for some comment. 



Several writers have devoted much space to this question, but the problem is far 

 from being actually solved. Bruce and others in discussing the matter cite the 

 following cases in regard to G. palpalis : — (1) in 60 flies in which blood was found, 

 20 contained mammalian, 9 non-mammalian, and 31 unrecognisable blood ; (2) in 

 108 other flies, 7 contained mammalian, 35 non-mammalian, and 66 unrecognisable 

 blood. 



With regard to the latter instance they note that reptilian was twice as frequent as 

 avian. 



Yorke and Blacklock give the following data from Sierra Leone : — 

 Flies. Mammalian. Nucleated. 



113 8 



87 6 2 



200 14 2 



These figures show great discrepancies ; e.g. in Bruce's first record the proportion 

 of mammalian to non- mammalian is over 2 to 1 ; in his second the proportion is as 

 1 to 5 ; while in Yorke and Blacklock's observations the proportion is 7 to 1. 



* [In G. tachinoides the third joint of the antenna is noticeably shorter and its anterior 

 edge is less curved. — Ed.] 



