170 The Philippine Journal of Science 1919 
well adapted to living in the crevices of beds and of rooms, by 
being depressed almost to the thinness of paper in the unfed 
and nongravid conditions. Its prehensile proboscis, which it 
carries folded along the median line of the ventrum when at 
rest, can be easily thrust forward for tapping its prey without 
the insect itself being obliged to come near enough to risk acci- 
dental crushing by the sleeping victim. 
All species of lice quickly suecumb—in the tropics, at least— 
when removed from the warm environment of the host’s body; 
but the bedbug, not being dependent upon the temperature fac- 
tor, can endure long periods of isolation from the host, this 
being particularly true of the newly hatched nymphs before they 
have had a meal of blood. In the North Temperate Zone both 
nymphs and adults* have been kept in closed vials for as long 
as a year without apparent injury. 
LICE 
Body lice, head lice, and crab lice, living upon animals (man) 
whose hair is more or less recumbent, or who are provided with 
. artificial covering in the form of clothing, have their bodies very 
markedly depressed, to enable them to glide readily from part 
to part of the host’s body and still maintain a position favor- 
able to the easy obtaining of food in the form of blood. All 
these insects have legs specially adapted to hair-clinging, the 
tarsal claws being reflexed upon the tarsi and provided with 
well-developed adductor muscles. The latter adaptation accounts 
for the necessity of “stroking” a head louse the length of the 
hair before it can be removed from its victim. A louse travels 
upon a single hair by means of the three legs on one side of 
its body. It will be observed that these legs are of the same 
length and almost identical in structure. 
Two or more carabao lice, when placed on a hair suspended 
by its extremities, will be seen to travel from end to end of 
the hair, passing and repassing each other interminably with 
the greatest ease, without losing their hold. 
The crab louse (Phthirus pubis L.), living among hairs that 
are stiffer and more nearly erect than those of the head, has 
a different morphological adaptation to its special needs. By 
means of the claws of the tarsi of its mid and hind legs it is 
enabled to grasp somewhat widely distant hairs on the body 
of the host. Pulling them toward each other, while it lies flat 
on the skin between them, it digs the claws of the tarsi of its 
*Insect Life (1889-1890), 2, 105. 
