352 Col. Sir D. Bruce and others. Tabamde  [Dec. 20, 
_ Habits—Emerging from the upper branches of the forest trees, on which 
they presumably shelter during the night, these flies commence feeding 
about 7 A.M. if the morning be fine with plenty of sunshine. They cease 
to feed about 6 P.M. Their most active hours are from 11 A.M. to 1 P.M, viz., 
the hottest part of the day. From 6 A.M. to 8 a.m. and again from 4 P.M. 
to 6 p.m., they are sluggish and do not feed readily. In wet, cold, or dull 
weather no flies are to be seen asarule. They bite cattle and man freely, 
but much prefer the former, and will rarely attack man in the presence of 
cattle. Their bite is like the stab of a sharp lancet, and draws a free 
trickle of blood from both oxen and man. They have followed cattle a 
distance of 3 miles to the laboratory, but invariably left the hill-top soon 
after their arrival, or died in sheltered spots about the houses a few days 
after their arrival. 
Variation im Incidence—This phenomenon is the most striking 
characteristic of the Tabanide. A forested stream known to be free from 
a certain species of Tabanus one day will be infested with that species 
during the next two or three days. This eruption, if it may be so called, 
appears to be simultaneous over a given area, and may be explained by the 
flies all arriving at maturity about the same day. This tends to show that 
the females all lay their batches of eggs about the same time. Further, it. 
is not unreasonable to date the commencement of the fly’s winged life from 
this time, and so, watching carefully for their final disappearance, we arrive, 
probably with some degree of accuracy, at the length of life of the fully- 
developed fly. The disappearance of the fly is almost as sudden as their 
eruption ; in some three days a locality previously swarming with a certain 
species of Tabanus will be quite free from this species. In this manner the 
Commission have observed carefully three species of Tabanide, viz., Tabanus 
secedens, Tabanus fuscomarginatus, and Tabanus thoracinus. In these cases, 
on the above computation, the limit of life of these flies is as follows :— 
Tabanus secedens, four months; Tabanus fuscomarginatus, two months ; 
Tabanus thoracinus, four months. At least two such eruptions of the same 
fly may occur in the same locality in the same year. 
The Tabande. 
Sez.—During the seven months (January—July, 1910) these experiments 
were taking place, many thousand Tabanidze were captured, but no male of 
any of the 12 different species was ever seen or taken. | 
The Hematopota. 
Halitat—The Hematopota have a more extensive range than the 
Tabanide. They are to be found in the same localities as the Tabanide, 
