Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists . hich have similar habits, we have found in abun-dance on the spruce in Maine, where it produces swellings atthe end of the twigs,resembling in sizeand form the conesof the same tree. The most destruc-tive insect of thisfamily is the GrapePhylloxeia, P. vitl- « Fig. 520. folice Fitch {P. vastatrix Planchon). It exists in two forms,one raising irregular galls on the leaves, and the other form-ing small swellings on the rootlets. The root-form is bot
Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists . hich have similar habits, we have found in abun-dance on the spruce in Maine, where it produces swellings atthe end of the twigs,resembling in sizeand form the conesof the same tree. The most destruc-tive insect of thisfamily is the GrapePhylloxeia, P. vitl- « Fig. 520. folice Fitch {P. vastatrix Planchon). It exists in two forms,one raising irregular galls on the leaves, and the other form-ing small swellings on the rootlets. The root-form is bothwingless and winged, the latter very rare. The leaf-form issaid to be always wingless. Fig. 521 (after Riley) representsthe windless leaf- -. form ; a, h, newlyhatched larva,ventral and dor-sal view; c, egg;d, section of leaf-gall ; e, swellingof tendril;/,//, //,mother gall-louse,lateral, dorsal,and ventralviews ; «, anten-na;/, two-jointedtarsus. Fig. 521^/,«, healthy root ; h, one on which the lice are working, repre-senting the swellings caused by their ]iunctures ; c, a rootwhich has been deserted bv them, and where the rootlets have. Fig. 521. 524 HEMIPTERA.
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectinsects
