GALL APLIIDS OF THE ELM. 237 



long as wide, and more pointed at the ends than in B. Pyri. Costal and 

 subcostal veins, and that bounding the stigma behind, robust and black. 

 Discoidal veins together with the 3d forked and stigmal veins, all slender 

 and black, the forked vein being as distinct to its base as are the others, 

 with the fork but 1-3 as long as the vein itself and curved in an oppo- 

 site direction to the stigmal vein. Antennae 6-jointed and of the same 

 color as the body; joints i, 2, 4, 5 and 6 of about equal length, joint 3 

 thrice as long as either. Legs of the same color as body. 



The young lice are narrower and usually lighter colored than the 

 mature individuals, varying from flesh or pink to various shades of blue 

 and purple." 



Biological and Discussion. 



The number of g"enerations of rileyi has not been ascertained. 

 The following records of my Maine collections do not throw 

 much light on this subject, but they are perhaps better than 

 nothing. 



Aphid 69-05. Sept. 2, 1905. Present in great numbers in woolly clusters 

 along trunk of small elms at Orono. Apterous viviparous form and 

 nymphs. This material was determined by Mr. Pergande as 

 Schisoneura rileyi during the winter of 1905-06. 



Aphid 95-06. August 4, 1906. Orono. Apterous and alate forms 

 present on trunk of young elm. 



Aphid 7-08. June 16, 1908. Woolly mass on trunk of small tlms. 

 Winged viviparous forms just developing from pupae. 



Aphid 89-08. Sept. 23, igo8. Orono. Apterous viviparous for:ns in 

 woolly bunches on trunk and branches of young Ulintis amcricana, caus- 

 ing knotty growth. The progeny of these apterous forms were the true 

 sexes, — apterous oviparous females and apterous males. Eggs were 

 plentiful under the bark. 



It will be noticed that there are two generations of winged 

 forms, one in June and one in August, and that apterous vivi- 

 parous forms were present during the same time. 



Not enough structural difference is found to separate rileyi 

 from americana, and I am inclined to consider them the same 

 species. Professor Gillette (1909) has made this same sug- 

 gestion. Figures are given of antcnn?e and wings of ]\'Iaine 

 material of rileyi and amcricana (figs. 152, 153, 157; 154, 159; 

 i'55, 158), for purposes of comparison. The wings are prac- 

 tically identical. The antcnnal differences might seem more 

 significant except for the fact that Riley's description of the 

 antenna of amcricana''" fits in every particular more nearly my 

 fall collection of rileyi than it does my spring collection of 



'See page in this bulletin. 



