166 



does not blow sheep in the summer months ; the green and bkie 

 sheep-maggot fly, Pycnosoma [Callijjhora) ruffacies, is a typical hot- 

 weather fly and has been found blowing live wool and carrion throughout 

 the year except during the cold weather of July and August. The English 

 sheep-fly [Liicilia sericaia] does not like extremes of either heat or 

 cold : its maggots are found in blown wool all through the early 

 summer. The shining black fly [Ophyra nigra] is not a blow-fly in the 

 strict sense of the term, being usually found all the year round under 

 the carrion on the damp soil, but it has adapted itself to blow live 

 wool ; the small green blow-fly, Pycnosoma {CalUphom) rarijjes, has 

 been bred from blown wool taken directly from the sheep's back and 

 has been found throughout the year except in July and August. 



Observations on sheep-maggot parasites have shown that in cases 

 where Nasonia brevicornis directly infests fly pupae in the paddocks, 

 the pupae attacked are always those of the two common green flies, 

 Pycnosoma rufifacies and P. varipes, while in laboratory experiments 

 it lays its eggs indiscriminately in fly pupae of any species without 

 exhibiting any preference. The discovery of another Chalcid parasite 

 of blow-fly maggots, Chalcis caUipJiorae, has already been recorded 

 [see this Review, Ser. B, iv, p. 179]. Although only a single individual 

 emerges from each fly pupa and the increase is therefore not so rapid 

 as in the more prolific N. brevicorfiis, the fact that the maggots are 

 parasitised before they seek cover or pupate may be a great advantage. 

 A new primary Hymenopterous parasite, which, however, is not of 

 much economic importance, has been obtained from the maggots of 

 Ophyra nigra. 



Jack (R. W.). Natural Transmission of Trypanosomiasis {T. peccrvm 

 Group) in the Absence of Tsetse-fly. — Bull Enlcm. Research, 

 London, viii, no. 1, August 1917, pp. 35-41, 2 maps. 



In this paper the author supplements the information conveyed in 

 a pre\'ious report [see this Revietv, Ser. B, v, p. 26] by detailed accounts 

 of outbreaks of trypanosomiasis, three being among cattle, and two 

 among pigs on isolated farms, some miles removed from a belt of 

 Glossina, ynmsitans. From these he concludes that, given the necessary 

 conditions, transmission of this disease may take place and has occurred 

 more often than has generally been recognised, in the absence of 

 tsetse-fly. 



It appears probable that the transmitting agents are abundant in 

 spring and summer, and decrease or disappear in the winter ; the 

 disease is not readily transmissible under S. Rhodesian conditions by 

 these agents from chronic cases that live over until the rains, or recover ; 

 such carriers are not capable of transmitting the disease indefinitely, 

 or only so under exceptional circumstances ; the method of trans- 

 mission is of a mechanical and not of a cyclical nature ; the segregation 

 of infected animals (on showing temperature) would, in the absence 

 of tsetse, effectively check the spread of the disease. 



The most probable transmitting agents are Tabanus fuscipes, 

 T. taeniola, Haematopota pertinens and other species of this genus, 

 Stomoxys calcitrans, Lyperosia and mosquitos. Of these, it must be 

 admitted that S. calcitrans and mosquitos are the only agents that are 



