130 Journal New York Entomological Society. t Vo1 - xxvu. 



lower leaf surface as cast skins of various stages are found here and 

 on no other part of the tree. 



Each nymphal stage requires from three to six days. The first 

 nymphs appeared May 13 and the first adults on June 12. Prac- 

 tically one month was required for the nymphal stages although cool 

 weather which prevailed from the middle of May throughout June 

 may have prolonged the lengths of the stages. The bulk of the 

 adults appeared during the last of June and the first part of July. 

 By July 12 no fifth stage nymphs could be found and overwintering 

 eggs were being deposited. There is but one generation each year 

 and adults are found in diminishing numbers throughout August and 

 .as late as October. 



The older nymphs and adults scattered considerably and could be 

 found on the leaves at the tips of the branches all over the infested 

 trees, even at the extreme top. As a rule the majority of adults were 

 found on the twigs. The adults were very active and usually moved 

 readily when disturbed. In common with many other species they 

 moved around the twig to the side away from observer. Even when 

 present in large numbers no appreciable damage to the foliage was 

 observed. Where many nymphs fed on the young leaves, the foliage 

 showed some slight malformation and whitening due to the abstrac- 

 tion of the sap, but the injury was not serious 



A9 the white poplar is a native of both Europe and Asia and 

 according to Keeler imported into this country very early, it seems 

 evident that Idiocerus cognatus was introduced in the egg stage with 

 this tree. In New Jersey, we have found it at Irvington, Asbury 

 (Warren Co.), Princeton Junction, Rutherford and Paterson and it 

 undoubtedly exists on white poplar at many other places. The New 

 Jersey records and those of Mr. Oslen for Long Island, N. Y., indi- 

 cate that it is well established jn the East. A description of the adult 

 and the synonymy is given in Mr. Olsen's paper in this issue and need 

 not be repeated here. For illustrations of the adult and of the male 

 and female genitalia see Mr. Olsen's paper. 



Egg. — Length 1.11 mm. Greatest width 0.35 mm. Translucent, 

 elongate, broadest at middle, slightly curved when viewed laterally, 

 broadly rounded at basal end, slightly tapering toward cap. Cap 

 oval, brown, with center light. 



First Nymphal Stage. — Length 1.34 mm. Width of head includ- 



