524 



HEMIPTERA. 



Legim to decay ; c?, c?, fZ, lice of natural size on the larger 

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

 f/, winged female, dorsal view ; /<, same, ventral view ; /, 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- 

 erte ; a, female mtifollm^ ventral view, showing the large egg 

 through the transparent skin of the body ; ?>, dorsal view of 

 the same ; c, tarsus, gi-eatly enlarged ; f?, shrunken anal joints 



as they appear after ovi- 



position ; c, male of another 



species, P. cary<PcauUs TMIey, 



dorsal view ; the dot in the 



I — ^^-^ circle indicates the natural 



Fig. 522. size of the insect. (After 



Riley.) 



Pemphigus formicarius is tended by ants. The Vagabond 

 Pemphigus, P. vagabmidus Walsh (Fig. 522), so-called from its 

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

 raises lai-ge galls (Fig. 524) on the tops of the cotton-wood and 

 balsam poj)lars; and the "old l)lackened galls hang on to the 

 twigs for several ^ea'^'^Mi'^, giving 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 species, the Pem2^higus rhois ol' 

 Fitch, and also the Cockscomb-elm gall (Fig. 525) made by 

 the P. tdmicola 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 winged plant- 



