114 Book-lice and Bark-lice; Biting Bird-lice 
siderable injury. They are called bird-lice, but they should not be confused, 
because of this name, with the true blood-sucking lice that infest many kinds 
of animals, particularly domestic mammals and uncleanly persons. The 
biting bird-lice (Fig. 143), constituting the order Mallophaga, never suck 
blood, but feed exclusively on bits of the dry feathers, which they bite off 
with small but strong and sharp-edged mandibles. The true lice have 
mouth-parts fitted for piercing and sucking, and 
constitute one of the numerous families of the 
order of sucking bugs, Hemiptera (see p. 217). 
More than a thousand species of biting bird- 
lice, or Mallophaga, are known, of which about 
two hundred and fifty have been found on North 
American birds. Although by far the larger num¬ 
ber of Mallophaga infest birds, numerous species 
are found on mammals. On these hosts the insect 
feeds on the hair or on epidermal scales. On 
both birds and mammals, therefore, the food con¬ 
sists of dry and nearly or quite dead cuticular sub¬ 
stances, and never of blood or live flesh. Those 
species of Mallophaga which infest birds are never 
found on mammals, and vice versa. 
The injury done to the hosts by these parasites 
consists not in the character of the food-habits, but 
chiefly in the irritation of the skin caused by the 
scratching of the sharp-clawed little feet of the insects 
in their migrations over the body. When, as hap¬ 
pens sometimes in poultry-yards and dovecotes, 
a fowl or pigeon is infested by hundreds of these active little pests, the 
afflicted bird becomes so restless and excited that it takes too little food 
and gets too little rest and thus grows thin and weak. The dust-baths 
taken by fowls and other birds are chiefly to get rid of the bird-lice. The 
fine dust, getting into the breathing-pores (spiracles) of the insects, suffocates 
them. So that the best remedies for these pests of the barn-yard are to 
see that the fowls have plenty of dust to bathe in, and also to keep 
thoroughly clean their roosting- and breeding-places. By tightly closing 
up the hen-house and burning sulphur inside (the fowls, it is hardly necessary 
to say, first being excluded) most of the infesting parasites can be killed. 
The life-history of the Mallophaga is very simple. The small elongate 
eggs are glued separately to the hair or feathers of the host, and from them 
young soon hatch (Fig. 144,3), which, except in size and, to some degree, in 
marking, closely resemble the parents. These young begin immediately their 
hair or feather diet, grow larger, moult a few times, and in a few weeks reach 
Fig. 143.—A biting bird- 
louse, Nirmus prce- 
stans, from a tern, 
Sterna maxima. (Pho- 
tomicrograph by 
George E. Mitchell; 
natural size,one-twelfth 
inch.) 
