296 MEDICAL ENTOMOLOGY 



has never been seen, and the majority of the females would not suck blood. 

 It is hot known how long a tabanid lives under natural conditions. 

 Observations on this point would be most valuable. 



Hine records having seen T. siilcifrons in copulo about 8 a.m. ; the 

 male clings to its perch, and the female hangs suspended with its legs 

 and wings motionless ; the whole act lasts about ten minutes. When 

 disturbed the male flies a short distance, and soon alights either on the 

 ground or on some low-lying foliage. 



It has frequently been noted that tabanids are in the habit of flying 

 over water, and darting down and striking the surface; these manoeuvres 

 are not very clearly understood, but Hine appears to think that both 

 sexes behave in this way and that they are merely sipping water. Hine 

 also considers that the female tabanid takes much food other than blood, 

 and that some may even pass their whole existence without taking blood 

 at all ; he has examined the alimentary tracts of both sexes and found a 

 yellow fluid, indicating that something else besides pure water or blood 

 had been imbibed. 



The Tabanidae always lay their eggs in the vicinity of water, and the 

 flies are never found very far from it. The habits of those species which 



have been studied show that there is considerable 

 Breeding Habits **!. ,.u j r i o 



and Early Stages vanatlon m tne methods of egg-laying. Some species 



oviposit almost entirely on particular plants, while 

 many do not select any special plant. The position in which the eggs 

 are deposited with respect to the depth of the water depends to a large 

 extent on the structure of larvae ; this is a point which would repay further 

 study. 



Hine has described the egg-laying habits of Tabanus stygius, Say, which 

 always oviposits on the upper surfaces of the leaves of the arrow plant, 

 placing the eggs above the point where the petiole meets the expanded 

 part of the leaf. Hine goes on to say : ' So closely is this habit fol- 

 ' lowed that a hundred masses of eggs are found thus located, to one placed 

 ' otherwise. Sometimes a mass is observed on a leaf of another plant, but 

 ' in the same location, and once in a long time eggs are seen in a different 

 ' location of a leaf '. The black horse fly, Tabanus atratus, Fabr., places 

 its eggs on a particular species of sedge in low ground near swamps or 

 ponds. Chrysops callidus, Osten Sacken, arranges its eggs in a single 

 layer on leaves of various kinds of plants overhanging water in ponds and 

 small lakes ; C. moerens, Walk., oviposits is similar places. 



King has recently recorded the egg-laying habits of several Soudanese 

 tabanids; Tabanus par, Walk., and T. taeniola, Pallisot de Beauvois, for 



