524 



HEMIPTERA. 



begun to decay ; cl, d, d, lice of natural size on the larger 

 roots ; e, female pupa, dorsal view ; /, the same, ventral view; 

 //, winged female, dorsal view ; />, same, ventral view ; i, mag- 

 nified antenna of winged insect ; J, side view of wingless 

 female laying eggs; k shows how the punctures of the lice 

 cause the larger roots to decay. Fig. 521 b, sexual Phyllox- 

 era? ; a, female vitifolke, ventral view, showing the large egg 

 through the transparent skin of the body ; ft, dorsal view of 

 the same ; c, tarsus, greatly enlarged ; d, shrunken anal joints 



as they appear after ovi- 



position ; e, male of another 



species, P. carymcaulis Riley, 



dorsal view ; the dot in the 



, — p--<- circle indicates the natural 



Fig. 52-2. size of the insect. (After 



liiley.) 



Pemphigus formicarius is tended by ants. The Vagabond 

 Pemphigus, F. vagabundus Walsh (Fig. 522), so-called from its 

 habit of wandering to very great distances in its native forests, 

 raises large galls (Fig. 524) on the tops of the eotton-wood and 

 balsam poplars; and the "old blackened galls hang on to the 

 twigs for several '^ca^nn^, oivinor the tree a singular appearance 



when the leaves 

 are off in the 

 wintertime." A 

 single female 

 begins the gall, 

 whose young 

 soon multiply, 

 leaving the gall 

 in September. 

 Mr. Walsh has 

 also described 

 Fig. 523. the Sumac gall 



(Fig. 523) caused by a smaller S'pecies, the Pemj^Ja'gus rhois of 

 Fitch, and also the Cockscomb-elm gall (Fig. 52.5) made by 

 the P. ulmicola of Fitch, which infests .young white elm trees, 

 often densely covering the leaves. "By the end of June or 

 the beginning of July, the gall becomes full of Avinged plant- 



