Siphonaptera , or Fleas 
123 
Mitzmain (1910) has described in detail the act of biting on man, 
as observed in the squirrel flea, Ceratophyllus acutus. “The flea 
when permitted to walk freely on the arm selects a suitable hairy 
space where it ceases abruptly in its locomotion, takes a firm hold 
with the tarsi, projects its proboscis, and prepares to puncture the 
skin. A puncture is drilled by the pricking epipharynx, the saw¬ 
tooth mandibles supplementing the movement by lacerating the 
cavity formed. The two organs of the rostrum work alternately, 
the middle piece boring, while the two lateral elements execute a 
sawing movement. The mandibles, owing to their basal attach¬ 
ments, are, as is expressed by the advisory committee on plague 
investigations in India ( Journal of Hygiene , vol. 6, No. 4, p. 499), 
‘capable of independent action, sliding up and down but maintaining 
their relative positions and preserving the lumen of the aspiratory 
channel.’ The labium doubles back, the V-shaped groove of this 
organ guiding the mandibles on either side.’’ 
‘ ‘ The action of the proboscis is executed with a forward movement 
of the head and a lateral and downward thrust of the entire body. 
As the mouth-parts are sharply inserted, the abdomen rises simultane¬ 
ously. The hind and middle legs are elevated, resembling oars. 
The forelegs are doubled under the thorax, the tibia and tarsi resting 
firmly on the epidermis serve as a support for the body during the 
feeding. The maxillary palpi are retracted beneath the head and 
thorax. The labium continues to bend, at first acting as a sheath 
for the sawing mandibles, and as these are more deeply inserted, it 
bends beneath the head with the elasticity of a bow, forcing the 
mandibles into the wound until the maxillas are embedded in the skin 
of the victim. When the proboscis is fully inserted, the abdomen 
ceases for a time its lateral swinging.” 
“The acute pain of biting is first felt when the mandibles have 
not quite penetrated and subsequently during each distinct move¬ 
ment of the abdomen. The swinging of the abdomen gradually 
ceases as it becomes filled with blood. The sting of the biting 
gradually becomes duller and less sensitive as feeding progresses. 
The movements of the elevated abdomen grow noticeably feebler 
as the downward thrusts of the springy bow-like labium becomes less 
frequent.” 
“As the feeding process advances one can discern through the 
translucent walls of the abdomen a constant flow of blood, caudally 
from the pharynx, accompanied by a peristaltic movement. The 
