150 THE EARLY STAGES OF TABANID^ 



juring even well developed Tahanus larvae. As soon as the insect 

 becomes aware of the presence of food, the claw-like mandibles are 

 protruded from the head capsule, and bury themselves in the live 

 food like meat hooks. With a slight curve dorsally, the larva's body 

 is brought forward, and a small portion of the food is lacerated. This 

 is aided by a twisting of the head and a pulling with the extended 

 jaws. The mandibles are brought together with a rapid clawing 

 action, the parts working in apposition. When prehension is effected, 

 the jaws move alternately upwards and downwards and laterally, 

 and the bolus is swallowed in fibrous strands. 



Seeking and devouring food is not a continuous operation as it is 

 in the case with Stomoxys and the dung-flies. The Tahanus larva 

 requires a long rest after a sufficient meal is taken. A 2 day old 

 Tahanus is capable of devouring two half grown larvae of Stomoxys 

 in twenty-five minutes. In one instance a full grown Stomoxys larva 

 was destroyed in exactly twenty minutes. Here the attack on the 

 Stomoxys was made through accidental collision, the Tahanus in- 

 stinctively thrusting out its mouth and tentatively taking a bite. 

 It apparently became greatly excited (this was its first meal), and 

 thrusting its head into the body of the Stomoxys larva, commenced 

 to probe by twisting its head rapidly. In less than a minute the 

 cuticle was broken through and an ample slit was made through 

 which the entire head was buried in the body of the victim, where- 

 upon an energetic gouging took place. The Tahanus worked through 

 the cephalic third of the body upwards to the head, then worked in 

 the other direction on the lower two-thirds. This gouging was con- 

 tinued until the Stomoxys had become completely eviscerated, during 

 which time the head of the Tahanus kept steadily probing, twisting 

 its pharynx from side to side, and pushing forward with its rostrum 

 until the Stomoxys larva was completely devoured with the exception 

 of the cuticle. 



The full grown Tahanus larva does not wait for its food, as is the 

 tendency in the young stage, but actively pursues its prey. When 

 an angleworm is seen, perhaps 2 mm. distant, the elastic head cap- 

 sule of the larva darts forth, curves its claw-like hooks about the 

 worm's body, and with its head curled under its struggHng prey, re- 

 treats quickly into the sand until all but its cephalic end is hidden. 



