The Grasshopper 



351 



weevils, which injure thousands of dollars worth of cotton annually, 

 while almost every type of grain has some sort of insect which uses 

 such grain as its food. 



As carriers of developing eggs or various immature forms of para- 

 sites, insects are now known to do great injury to man as well as to the 

 animal world at large. The classic example is that of the anopheles 

 mosquito, which carries malaria, and the tse-tse fly, already referred to 

 as the carrier of the germ of sleeping sickness. 



Fig. 228. 

 Lice — both animal and plant. 



A. Female of flea, Pulex irri- 

 tans, infesting man. (After 

 Herms.) 



B. Sarcoptes 

 female itch mite. 

 Leuckart.) 



scabei, 

 (After 



C. Order A carina. Harvestmites 

 or "chiggers." Leptus irritans on 

 the right; L. americana on the left. 

 (From Osborn, after Riley.) 



D. Common cat and dog flea (Pulex ser- 

 raticeps) : 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 o£ 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. Phylloxera vastatrix: 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.) 



w 





\h 



'-^J 



jffS^ 



ta^ 16 



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jj/'df 



Wl "**"**-' 







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F. Phylloxera vastatrix: 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) hexactews, (After Ou- 



root-gall louse much en- demans.) 

 larged. (Marlott.) 



