Bugs, Cicadas, Aphids, and Scale-insects 217 



give a firm hold for the penetrcating bristles arranged as chitinous strips in 

 a long, slender, flexible tube terminated by four very minute lobes which 

 probe to the capillary vessels of a svi^eat-pore." Of the three species of 

 Pediculus infesting unclean persons, P. capitus (Fig. 299), the head-louse, 

 is longer than wide, whitish with faint dark markings at the sides of the 

 thorax and abdomen; P. vestimenti (Fig. 300), the body-louse, is of the 

 same shape and general a])])earance, but when full grown has the 

 dorsal surface marked with dark transverse bands; while P. ingiiinalis 

 (Fig. 301), the crab-louse, has the body as wide as long, with strong 

 legs spreading out laterally so as to increase the apparent width very 



Fig. 301. 



Fig. 302. 



Fig. 303. 



Fig. 301. — The crab-louse of man, P/W/i/rii(\ i«?"'«"'"- (After Lugger; much enlarged.) 

 Fig. 302. — Egg of crab-louse, Phthirius inguinalis. (After Lugger; much enlarged.) 

 Fig. 303. — Sucking dog-louse, Hmmatopinus pilijerus Burm. (After Lugger; natural 

 sire indicated by line.) 



much. The eggs (Fig. 302), called "nits," of these lice are whitish and are 

 glued to the hairs (in the ca.se of P. capitus) or deposited in folds of the 

 clothing (P. vestimenti), and the young, when hatched, resemble the parents 

 except in size. The whole life is passed on the body of the host. The prime 

 remedy for these disgusting pests is cleanliness. Various sulphur and mercu- 

 rial ointments will kill the insects. 



The lice of the domestic animals belong to a different genus, Ha-ma- 

 topinus, but are very similar in appearance and structure to the head-lice 

 of man. H. pilijerus (Fig. 303), of dogs, is about ^^r inch long, reddish 

 yellow, and with the abdomen thickly covered with fine hairs and minute 

 tubercles; H. eurysternus (Fig. 304), the short-nosed ox-louse, of cattle, 

 is from J inch to | inch long, fully half as wide, with the head bluntly 

 rounded in front and nearly as broad as long; H. viluli, long-nosed ox-louse, 



