OF WASHINGTON, VOLUME XVIII, 1916 11 



Alate aphids of all forms have now been recorded. Alate 

 sexual ovipara are rare, but alate males are of very common 

 occurrence. In some species two forms of males are known to 

 exist, alate and apterous. The males in certain other species 

 are, in our opinion, clearly intermediate in nature between alate 

 males and typically apterous males. The male of Toxoptera 

 mullenbergiae Davis is apterous and yet it retains many char- 

 acters of the typically alate male. The thorax possesses fairly 

 distinct alate characters. This is of such a prominent nature 

 that the insect suggests an alate with the wings removed. What 

 is even more significant is the fact that the ocelli are present. 

 These two characters show the undoubted intermediate char- 

 acter of this male. What has been said of mullenbergiae might 

 also be said of the male of Aphis striplex Lin. This form likewise 

 possesses remnants of the alate thorax and distinct ocelli, and is 

 undoubtedly intermediate in nature. It is interesting to note 

 that while in some males of atriplex the alate thoracic characters 

 are well retained, in others they are represented by faint markings 

 only. Both of these males might well be compared to the inter- 

 mediate vivipara of Phyllaphis fagi Lin., herein described, except- 

 ing that the wings in that form are not entirely reduced. 



The number of species with typically apterous sexed ovipara 

 is very large. If the primitive aphids were sexed this condition 

 would be expected much sooner than species with entirely 

 apterous viviparae. 



Of the species of which intermediates are described in the present 

 paper the writers have carried three throughout their entire 

 cycles. ( These three have annual cycles and alternate hosts. 

 They are Macrosiphum viticola Thos., Aphis prunifoliae Fitch (the 

 avenae Fab., of American authors) and Aphis malifoliae Fitch 

 (the sorbi Kalt. of American authors). In the first two species 

 the intermediates have occurred upon the summer hosts and 

 were intermediates between summer apterae and summer alates. 

 This is also true of the intermediates of another species, persicae 

 Sulz. Malifoliae Fitch winters upon the apple and spends the 

 summer months upon species of Plantago, particularly upon rib 

 grass. Alate forms during midsummer seem to be rare. The 

 intermediates of this species occurred upon apple and were 

 intermediates between alates which cannot live upon apple but 

 must fly to plantains and apterae which cannot live upon plan- 

 tains, but only upon apple. The intermediates lived and re- 

 produced upon apple, thus taking on the nature of the primary 

 apterous forms. 



Following are descriptions of viviparous intermediates of 

 seven species of aphids. One character is noticeable in all of 

 these forms. The remnants of the wings hang drooping at the 

 sides of the insects. They have lost the support of the muscles. 



