26 



longest ; fourth and fifth subsequal and about equal to the thickened 

 proximal part of the sixth. Cornicles short, tapering towards the 

 tip, not swollen, extremities flared. Cauda short and wide. Length 

 of body, 1.4 mm. ; width of body, .93 mm. : antennae, .57 mm. 



The young of this form are paler in color and have proportionally 

 longer rostra and shorter cornicles. 



Winged viviparous female [aerial form]. — Head black. Thorax 

 chiefly black above. Abdomen pale green, faintly bluish at sides, 

 with three marginal black spots on each side preceding larger spots 

 which surround the bases of the cornicles. Antennae chiefly black. 

 Cornicles black. Cauda green, edged with black. Segments behind 

 the Cauda dark-edged. Head and thorax beneath chiefly black. 

 Abdomen pale green, with two transverse black marks preceding the 

 Cauda. Legs pale at their articulations; middle part of tibiae often 

 pale. Rostrum chiefly black. Body more slender than that of the 

 female of the root form. Antennae rather long ; fourth and fifth 

 articles each longer than the basal part of the sixth. Cornicles 

 moderately long, swollen in the middle. Length of body, 2 mm, ; 

 width of body, .87 mm. ; antennae, about .85 mm. : cornicles, .2 mm. ; 

 wing, 2.65 mm. 



Pupa of winged viviporous female [aerial form]. — Head dark brown, 

 often presenting an appearance of two longitudinal dark bands. 

 Body chiefly pale green. Wing-pads, cornicles and tip of cauda 

 black. Antennae chiefly dark. Beak dark at base and tip. Legs 

 nearly all dark ; tibiae pale proximally. Length of body. 1.6 mm. ; 

 width of body, .62 mm. ; antennae, .7 mm. ; cornicles, ,12 mm. 



Wingless viviparous female [aerial form].— General color pale green, 

 with Cauda, cornicles and greater part of the rostrum, antennae, and 

 legs black. Head with two broad, approximated, longitudinal dark 

 bands which give the prevailing color. Abdomen with the usual 

 marginal black spots and the black patch about the base of the 

 cornicles. Antennae dark at base and apex. Eyes reddish brown. 

 Anterior legs mostly pale. Rostrum dark at base and apex. IVIore 

 slender than the female of the root form and of a brighter green 

 color. The cornicles are swollen in the middle. Length of body, 

 1.97 mm. ; width of body, 1 mm. ; antennae, .75 mm. ; cornicles, 

 .17 mm. 



The young of this form differs from the adults in the same manner 

 as do those of the root form, /. e. they are more slender, have 

 longer beaks and shorter cornicles. 



Towards fall the green color worn by the adults is changed for 

 darker colors and often females which are still giving birth to young 

 are bluish black. A meal-like coating can be detected on the bodies 

 by examination with a lens. 



LIFE HISTOEY AND HABITS. 



Naturalists hold to the belief that it is not in accordance with 

 natural law that a species of animal should reproduce indefinitely 

 without the union of the male and female sexes. It is true that 

 when supplied with heat and food artificially, certain species of 

 Aphides have been induced to reproduce for long periods without 



