166 INSECTS AFFECTING DOMESTIC ANIMALS. 
different species have been present, since the conditions favoring the 
increase of one will also favor the others. The reports, especially of 
the earlier writers, have many of them doubtless been subject to great 
exaggeration, for while the normal rate of increase will account for the 
sudden appearance and rapid multiplication of the lice under certain 
conditions, it is not equal to the marvel- 
ous stories which are to be met with 
even in some works that lay claim to 
accuracy. 
The crab louse infests particularly the 
pubic regions, but occurs also among the 
stiff hairs under the arms, in the beard, 
and it is said also among the hairs of 
the eyebrows. It does not live in the 
‘ i, Ae pere fine hair of the head. 
ue ne SE Ma It is very distinct from the other 
species, the body being nearly as wide 
as long, while the strong legs spreading out laterally very greatly 
increase its apparent width and give it the form of a crab in miniature, 
thus winning for it the name of crab louse. It is of a whitish color, 
with a dusky patch on each shoulder, and with the legs slightly tinged 
with reddish, the claws having this color more pronounced. It is nearly 
one-tenth of an inch in length. 
The remedies adopted for the head louse are applicable to this spe- 
cies, although it is said they are less effectual and must be persisted in 
more vigorously. Red precipitate is probably most frequently used. 
THE HEAD LOUSE. 
(Pediculus capitis DeGeer.) 
This louse has been recognized under one name or another as far 
back as we have history. While very generally confused with the 
following species, it is probably the one most commonly known, though 
perhaps not the one which has caused the greatest amount of annoy- 
ance or that has occurred in the greatest numbers. The two species 
were not clearly defined till comparatively recent times. 
Elaborate writings upon the louse were given by Swammerdam, 
Leeuwenhoek (1693), and descriptions of it by Redi, DeGeer, Linnzus, 
Geoffroy, Burmeister, Leach, and others, besides innumerable brief 
mentions and a goodly number of elaborate memoirs upon its embry- 
ology, etc. In later days, while a most annoying pest, it does not 
appear to have caused such serious results as the body louse or the 
crab louse. 
It is confined to the fine hair of the head, rarely occurring on other 
parts of the body. 
The eggs (nits) are white and glued to the hair at some distance 
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