VETERINARY ENTOMOLOGY FOR INDIA                  195

experienced in inducing many of the bred specimens to feed. It was found that
bright sunshine is essential, and that it is usually several days after hatching before
the first meal is taken ".

    Cross and Patel [1921] found that Tabanids preferred to bite surra-infected
animals rather than a healthy one and that buffaloes were the favourite hosts,
donkeys being the least preferred. They are of the opinion that Tabanids find
their hosts by means of sight and not by smell, and this view would seem to find
support in the observations made in South Africa where it is stated that several
species of Tabanids are attracted to dummy animals (Jl. Dept. Agric. Union S.
Africa, VIII ; 1923).

    It seems possible that advantage of this habit may be taken by using decoy-
traps such as have recently been adopted in Africa for trapping Tsetse Flies. That
Tabanids are attracted by moving objects, even a railway train, is a common
observation when travelling in India and they may often be carried long distances
in this way.

    As regards the feeding habits of Tabanids in captivity, observations at Pusa
(vide Report of Entomological Section for 1915-16) showed that when bred females
of Tabanus nemocallosus, starved under humid conditions for 24 hours after emer-
gence, were allowed to bite under cover of test tubes the shaven and moistened
skin of a goat, they sucked blood within five minutes. Further they were capable
of resisting starvation for 5 days in humid surroundings, showing a marked
tendency to drink water, and if the habit of sucking sugary food was acquired, the
blood-sucking habit was resumed with reluctance. Nieschulz [1927] in Java,
observed that T. rubidus and T. striatus could live for 70 days in captivity and that,
if opportunities were given, they sucked blood on an average rather oftener than
every second day.

    The actual mechanism of biting in the Tabanidæ has been discussed by Surcouf
and his account is briefly reproduced below. The part of the skin to be attacked
being first selected by feeling it with the proboscis, the labella are retracted, the
stylets are evaginated and enter into action in the following fashion: the mandibles
are rotated inwards under the action of the adductor muscles and the cutting blades
penetrate obliquely in the tissues, then they are brought back to their original
position by the abductors; their action is comparable to that of a section of a saw
worked by alternate movements. During this time the maxillæ are alternately
pushed forward and brought back in position by their corresponding muscles in.
two different directions and at each retreat the barbed blades cut through the
tissues. According to Nitzulescu [1926], the buccal armature of Tabanids more
closely resembles that of Phlebotomus (" Sand-flies ") than that of mosquitos.

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