APHID^. 



523 



swellings on twigs like pine and spruce cones. The antennae 

 are short, five-jointed and slender ; there are three straight 

 veinlets arising from the main subcostal vein and directed out- 

 wards, and there are no honey tubes ; otherwise these insects 

 closely resemble the Aphides. A species (Fig. 520 ; a, pupa 

 seen from beneath) closely related to the European Adelges 

 (Chermes) coccineus of Ratzburg, and the A. strobilobius of 

 Kaltenbach, which have similar habits, we have found in abun- 

 dance on the spruce in Maine, where it produces swellings at 

 the end of the twigs, 

 resembling in size 

 and form the cones 

 of the same tree. 



The most destruc- 

 tive insect of this 

 family is the Grape 

 Phylloxera, JR. viti- a Fig. 520. 



folke Fitch [P. vastatrix Planclion). 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 both 

 wingless and winged, the latter very rare. The leaf-form is 

 said to be always wingless. Fig. 521 (after Riley) represents 

 the wingless leaf- j 



form ; «, b, newly ^ _^^^!jfttaL 

 hatched larva, 

 ventral and dor- 

 sal view; c, egg; 

 d, section of leaf- 

 gall ; e, swelling 

 of tendril ; f, g, h, 

 mother gall-louse, 

 lateral, dorsal, 

 and ventral 

 views ; i, anten- 

 na; J, two-jointed 

 tarsus. Fig. 521 a, 

 «, healthy root ; h, one on which tlie lice are working, repre- 

 senting the swellings caused by their punctures ; c, a root 

 which has been deserted by them, and where the rootlets have 



