INSECTS AFFECTING PARK AM) WOODLAND TREES 635 



(,f the discasfd I issues. I'l-esh excavations are bright .green, showing tliat 

 tlie dentate niandiljles arc very eflective tools. The gall is sometinus 

 inhabited l)y an undetermined curculionid larva. 



This gall insect is preyed on bx' a parasite, determined through the 

 courtesy oi Dr Howard as Urogaster forljesi Ashm. This gall- 

 making tly has been reared by Professor \\'el)ster from larvae- burrowing in 

 the roots of clover and tunneling the pith of tin- common garden sun- 

 flower, and Mr Pcrgande has brt:d it from stems of ambrosia. 



Vagabond gall 

 Pemphigus vagdluindiis Walsh. 



A peculiar folded convolute mass of foliage some two inches in diameter, frequently 

 occurs on the tips of poplar twigs. 



This species appears to be rather common In the; vicinity <>f Albany, 

 and the peculiar convolute, greenish galls or llu; dry brown remains of the 

 same may often bi- met with on poplar shoots |pl. 51, lig. i ]. 



This gall is sometimes very abundant on the lips of certain cotton- 

 woods ancrpoplars. and according to Walsh is much more niunerous some 

 years than others. The old blackened galls hang on the twigs for several 

 seasons, thus giving thc-m a characteristic appearance, particularly in winter. 

 The winged plant lice make their appearance in September, and the green, 

 shining, hollow gall appears the following summer. The skin of the latter 

 is quite thin and contains a single wingless plant louse, which is the pan-nt 

 of the colony subsequently inhabiting this peculiar shelter. All become 

 winged in September and desert the gall. 



Poplar leafstem gall 

 J\mphigus popitli-transvcrsus Riley 

 Oval, somewhat elongated galls, with transverse openings, develop near the middle 

 of the leaf petioles of cottonwood during the latter j.art of the summer. 



The galls are n<-arly ■, inch long, about :^ s inch in breadth, and of the 

 same color as the leaf petiole. The mouthlike orifice, when the plant lice 

 are mature, gapes, is nearly transverse and may extend two thirds the way 



