350 



GENERAL BIOLOGY 



Lice (Fig. 228), and other so-called vermin (all of these belong to 

 the insect group), are not only injurious to higher forms of life by their 

 acts, but also as carriers of disease. 



The common house fly carries dirt and filth from the garbage can 



A. Female of flea, Putex irri 

 tans, infesting man. 

 Herms.) 



Fig. 228. 



Lice both animal and plant. 



B. Sarcoptes scabei, C. Order Acarina. Harvestmites 



(After or "chiggers." Leptus irritans on 

 the right; L. americana on the left. 

 (From Osborn, after Riley). 



(After female itch mite. 

 Leuckart). 



D. Common cat and dog flea (Pu'lex ser- 

 rat'iceps) : a, Eggs: b, larva in cocoon; c, 

 pupa ; d, adult ; e, mouth parts of same from 

 side ; /, labium of same from below ; g, an- 

 tenna of same ; all much enlarged. ( Howard, 

 Bull. U. S. Dept. of Agriculture, 1896). 



Rat Fleas. It is believed that in tropical 

 countries the disease germs of the bubonic 

 plague may be transmitted from rats to men 

 by the bites or punctures of rat fleas. 



E. Phylloxe'ra vasta'trix : a, Leaf with 

 galls ; b, section of gall showing mother 

 louse at center with young clustered about ; 

 c, egg ; d, larva ; e. adult female ; /, same 

 from side. (a. Natural size; b-f, much en- 

 larged). (Marlatt). 



F. Phylloxe'ra vasta'trix: G. Pediculoides ventricosus, H. Head and Pronotum of (a) dog 



a, Root-galls; b, enlarge- male. Grain louse which flea; (b) of cat flea; (c) hen flea, 



ment of same, showing affects farmers and thresh- (After Rotschild.) (d) Nycteridiphilus 



disposition of lice; c, a ers. (After Braun). '(Ishnopsyhus) hexactenus. (After Ou- 



root-gall louse, much en- demans.) 

 larged. (Marlott.) 



and manure pile to the food it lights upon, as well as to the baby's drink- 

 ing bottle. In this filth, it thus deposits, there are hundreds of tiny eggs 

 and seeds which as soon as they receive the necessary moisture and heat 



