332 SANITARY ENTOMOLOGY 



female about one-eighth to one-fifth of an inch, while the males are a 

 little smaller and a little narrower. 



The eggs or nits are white and can be distinctly seen glued tightly to 

 the hairs along the shoulders. From thirty-five to fifty eggs are laid by 

 the mature females and these are laid a few each day. The egg-laying 

 period may extend over a period of ten to fifteen days. These eggs 

 hatch in from seven to eight days and the young lice commence draw- 

 ing the cow's blood near the point where they were hatched. The rate 

 of growth depends somewhat upon the blood supply in the portion of 

 skin where they work. They mature in from fifteen to eighteen days, 

 when the females in turn lay eggs. 



The long-nosed cattle louse, Haematopinus vituli Linnaeus, is often 

 spoken of as the "blue louse," or the louse attacking calves, though it 

 occurs frequently on older stock. It is distinguished by being darker in 

 color and slender in shape with a long pointed head. When seen on the 

 cattle it seems to be literally standing on its head with mouth-parts buried 

 in the skin, feeding on the blood of the animal that it infests. It is 

 found more commonly on the neck and shoulders of the animal. 



The mature insects are a dark bluish gray in color, giving them an 

 appearance of being either blue or black, and they are about one-eighth 

 of an inch long. Their color and their small size allow them to pass 

 unnoticed especially on stock of a darker color. If one will turn back 

 the hair until the skin of the animal can be seen, their presence may be 

 made out by the shining surfaces of the abdomen. If they can be made 

 out on the calves having white markings, they can usually be assumed to 

 be present on the others, and there should at least be a close observation 

 of all the calves. 



The eggs of this louse are dark, nearly black, and hatch in from 

 eight to nine days. Like the previously mentioned species, these lice 

 move about but little before maturity, but continue feeding near the 

 point where they were hatched. They in turn lay eggs in fifteen to 

 eighteen days. 



BITING lilCE 



The little red cattle louse, Trichodectes scalaris Nitzsch, is perhaps 

 the most generally found on cattle. It seems to be out of place as it is 

 of the biting group, and this group is most commonly found on birds. It 

 feeds on the hair and loose scales of the skin, and the drier the skin of the 

 cow, the more numerous these lice become, until they can be made out by 

 the thousand, closely matted in the hair. They are most commonly 

 found on the neck and shoulders, though in bad cases they are found 

 pretty generally over most parts of the animal. Unlike the two previ- 



