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 e.xcited 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 e.xcluded) mo.st 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 



/I;;/ 



Fig. 143. — A biting bird- 

 louse, Nirmiis prce- 

 stans, from a tern, 

 Sterna maxima. (Pho- 

 tomicrograph by 

 George E. Mitchell; 

 naturalsize, one-twelfth 

 inch.) 



