38 THE CANADIAN ENTOMOLOGIST. 



irregular horizontal spots on either side of abdomen around pores of 

 connexivum above spiracles. 



Varieties. 



Specimens of Nectarophora, on lettuce : collected at Lexington, Ky., 

 in Feb., 1895 (Nos. 12, 26), kindly loaned me by Prof. H. Garman ; on 

 lettuce in Baltimore County, Md., Feb., 1899 (No. 14), by Prof. W. G. 

 Johnson ; and on clover at Ames, Iowa (Nos. 1 6, 28), by Mr. F. A. Sirrine 3 

 have all been carefully studied and measured. A similar form was also 

 taken at Milford, Del., on peas, May 1, 1900. 



The dimensions of series of these aphids, as given in the table, shade 

 into each other and N. destructor and pisi so as to make it impossible to 

 separate them satisfactorily on any distinctions of size. It should be 

 remembered that the measurements of the table merely give the average 

 size of each series and that individual specimens vary widely from them. 

 Numbers 12, 13, 14, 15, 26 and 27 are of the same variety. They may 

 be distinguished by segment III. of the antennse of the apterous 

 viviparous females bearing six to eight sensoria, about half of which are 

 much larger than the remainder, while N. pisi has but one ; the tips of 

 the cornicles in both winged and wingless are reticulated as in No. 1 

 N. pisi from England, whereas in American forms of N. pisi ( N. 

 destructor) they are plain. A single winged male, seemingly of this 

 species, was taken on lettuce at Newark, in Dec, 1899. It (No. 17a) is 

 similar to the male of pisi, except that it is smaller and IV. has two 

 sensoria, which are lacking in pisi, the sensoria on III. and V. being 

 similar. 



The winged (No. 16) and apterous (No. 28) viviparous females from 

 Iowa lack the reticulation on the cornicles, and the sensoria are as in 

 N. pisi, though they are so much smaller that they are probably a 

 distinct variety. The apterous forms from Iowa (No. 28) are "stem 

 mothers," having been hatched from winter eggs. They differ from the 

 other apterous forms in the shorter antennae and legs, and in VII. being 

 shorter than III. It is not unusual, however, for the stem mother to 

 differ from other broods. No distinctive characters could be found in 

 the wing venation of any of these specimens. 



For the present, therefore, from the material studied, we are obliged 

 to consider all of these specimens as varieties of N. pisi, Kalt. A larger 

 series and further observation of their life-histories may reveal specific 

 distinctions. The present account is published merely to show the extreme 



