INSECTS IN RELATION TO MAN. 559 



third species, the louse of Phthriasis (Ped. tabescentium) , which is the 

 nearest to the two preceding, has longer antennae, a larger and more 

 distinctly separated thorax, and an indistinctly ringed abdomen, espe- 

 cially at the sides ; at its apex there are four strong setae. It only 

 originates with Phthriasis, and lives like the former upon the skin at 

 parts where folds are formed and much perspiration collected. It has 

 been recently observed by Alt, in Bonn. * The fourth, or Ped. pubis, 

 Lin., has a contracted body, a very broad thorax, short thick legs, and a 

 two-pointed abdomen, it being emarginate at its apex. It is found 

 amongst the hair of the arm-pits and of the pubis, and sometimes 

 even in the eyebrows, and is also found only amongst dirty people. 

 According to Fabricius t the louse of the Negro is a fifth specifically 

 different species peculiar to mankind. It is black, and has a large, flat, 

 triangular head, two-pointed in front, and a wrinkled uniformly black 

 abdomen. 



Next to the louse the flea is the most general parasite upon man ; 

 yet, as we have already mentioned, it is parasitic only in its perfect 

 state, and accompanies man by day and by night, tormenting him with 

 its painful punctures. Children and girls are particularly annoyed by 

 it. That the flea of man is of a peculiar kind recent observations have 

 made probable. A second species of the genus Pulex, the cliique, 

 pique, jigger, nigua, tunguci (Pulex penetrans, Lin.), is found in 

 America, and nestles in the flesh beneath the nails of the toes, where it 

 deposits its eggs. It thus speedily raises such swelling and irritation 

 that if the dangerous enemy be not speedily removed inflammatory 

 swellings originate, which quickly affect the whole limb. If, as some 

 observers have remarked, this creature does not pass through a perfect 

 metamorphosis, it will, notwithstanding its resemblance to the flea, not 

 belong to the genus Pulex, but must form a distinct genus of the 

 Hemiptera, in the vicinity of the lice. Pediculus ricinoides, of 

 Fabricius, is, without doubt, the same creature, and, from the informa- 

 tion he had received of its imperfect metamorphosis, was placed by him 

 among the lice J. 



Besides the flea, the bed bug (Acanthia lectularia, Fab.) is known 

 as a parasite of man. It is found in the joints of bedsteds, and is 

 not rare, especially in large towns, and when once they have nestled 



* Alt Dissertatio de Phthriasis. Bonnffi, 1820. 4to. 

 f Systema Antliatorum, p. 240. 2. J Ibid., p. 341. 4. 



