''122 ENTOMOLOGIAL OBSERVATIONS MADE BY THE 



It must be explained that T, pecorum is proposed as a new name in order 

 to clear up the confusion which at present exists in the nomenclature of 

 the 7\ dimorplioii group. This new name is stated to include Trypanosoma 

 dimorphon, T. congolense, the trypanosome discovered in Zanzibar by Edington, 

 that from Portuguese East Africa and Zululand described by Tlieiler, and 

 the species found in Northern Rhodesia by Montgomery and Kinghorn, and 

 in Southern Rhodesia by Bevan. 



It was found by experiment (one case out of four) that T. pecorum is 

 capable of developing in a wild specimen of G, palpalis, and of infecting a 

 bealthy animal after a period of 21 days. But it is noted tlint in no instance 

 did Trypanosoma pecorum aj;)pear in the blood of animals upon which freshly- 

 caught Lake-shore flies had been fed ; the only trypanosomes with which 

 such flies were found to be naturally infected being T. gamhiense and T. vivax. 

 It would appear from this that G. palpalis is probably not the common or 

 chief carrier of T. pecorum. 



With regard to Tabanid^, no experimental evidence is available as yet, 

 •owing (so the Avriter is informed by Sir David Bruce) to the impossibility of 

 keeping these insects alive in captivity for more than two or three days. But 

 the authors make tlie following suggestive comments on these iiies : — 



'' There is some circumstantial evidence available to show that 'Trypanosoma 

 pecorum is carried by Tabanid^. In the valleys round Mpumu HiJl, so far 

 as we are aware, there are no tsetse-flies at any time of the year. As a rule, 

 there are a few Tabanid^e. The cattle belonging to the Commission went 

 ■down to the foot of the hill every morning to graze, and returned to their 

 kraal on the top at sunset. Half of the herd went to the east of the hill and 

 half to the west. On both sides there was a small valley or glen, through 

 which ran a small stream. In these valleys during the year, as a rule, a 

 Tahanus or two or a Ilcematopota could be seen, but they were in small 

 numbers. Now it is a curious fact that at certain times of the year enormous 

 numbers of Tabanid/E will suddenly appear in places where only a few are, 



as a rule, to be found So, in the same way, at Mpumu, the 



Tabanid^, which had been rare, suddenly appeared in swarms. They were 

 first seen in the valley to the west of the hill in September, 1909, and a 

 month later in the valley to the east. Soon after this the cattle, which had 

 shown no signs of disease during the previous year, were found to be suffering 

 from Trypanosoma pecorum. Those which grazed in the valley to the west 

 were the first to be affected, and afterwards those which grazed to the east of 

 the hill. The species of Tabanidj^ in this case was Tahanus secedens, Walk. 

 In both groups of cattle there were cases of Trypanosoma pecorum disease, so 

 that the Tabanid^e had a reservoir from which to draw the virus. 



" Another sudden epidemic of Trypanosoma pecorum disease occurred on 

 Mr. Walsh's farm at Kabula Moliro, where 34 milch cattle died within two 

 months in a herd of 300. The evidence is all against this epidemic having 



