40 



at Boston, is apparently untouched in Washington. In other parts of 

 the city the Coccids have been found in several instances upon the 

 trunks of the large TJ. americana, but these trees are too tall to mount 

 readily to ascertain the numbers on the limbs. On the infested TJ. 

 montana at the Department the old females cluster thickly along the 

 under sides of the lower limbs, and through July the young are scat- 

 tered over the leaves feeding vigorously and growing rapidly. Were 

 we considering this question of the varieties attacked from the Wash- 

 ington trees only we could very plausibly account for the occurrence 

 of the species so abundantly upon montana and not on campestris for 

 the reason that the leaves of campestris are completely skeletonized 

 every summer by the larvae of the imported Elm-leaf Beetle, while the 

 leaves of montana are only partly eaten, thus giving the young Coccids 

 abundant opportunity to develop on the latter and none at all on the 

 former species; but unfortunately the facts from Cambridge obviate 

 this simple conclusion. 



Fig. 5.— Gossyparia ulmi: a, female before impregnation— greatly enlarged; b, male cocoons in 

 natural position on limb— natural size; c, perfect male — greatly enlarged (original). 



Upon ascertaining definitely during May the identity of tbe species 

 with the European Gossyparia ulmi it immediately occurred to us as a 

 matter of coarse that it was quite natural that the insect should be 

 abundantly found in the two localities of Boston and Washington in 



