GENERIC CLASSIFICATION OE APHIDIDAE. ( 



and the other toward the development of them.. The first sub tribe, 

 the Monaphidina, lacks cornicles above. The second of these two, 

 the Drepanaphidina, possesses them in varying degrees. In this last 

 subtribe the males are winged, and the females have developed an 

 extremely long, narrow ovipositor. 



Coming now to that line represented by Chaitophorus, the Chai- 

 tophorina are found to be the most generalized, corresponding quite 

 closely with the Callipterina. In this subtribe males are winged as a 

 rule, but sometimes in the same species they are intermediate or 

 apterous. Arising from the same branch with the Chaitophorina 

 are two subtribes specialized in different directions, like the sub- 

 tribes of Callipterus. The first, Fullawayina, lacks cornicles entirely, 

 whereas the Pterocommina has developed them in varying degrees, 

 as has the Drepanaphidina. This concludes the subtribes of the 

 Callipterus branch. 



In connection with these insects the tribe Oreenideini should be 

 considered. The cornicles of the primitive aphids were evidently 

 small, somewhat rounded or conical, and armed with hairs. In the 

 Greenideini the insects have very long cylindric or somewhat swollen 

 cornicles which are thickly covered with prominent hairs. No such 

 well-developed cornicles are met with in any of the other tribes of the 

 family, although they are approached in the Macrosiphina. In this 

 latter subtribe species occasionally occur which show a few short hairs 

 on the cornicles. It seems evident then that the Greenideini separated 

 from the Aphidinae before the hairs of the cornicles disappeared. 

 This was evidently more recent than the development of the tribe 

 Lachnini which possesses a much more primitive cornicle. At about 

 the same time that the ancestors of the CaUipterini separated from 

 the Aphidinae, other forms probably separated and more or less 

 paralleled in some ways the ancestors of the Macrosiphina, but unlike 

 them carried the hairs of the cornicles. They thus resulted in forms 

 with very long cornicles similar to those of the Macrosiphina but 

 armed with long hairs. In other characters, too, they of course differ, 

 particularly in regard to the cauda. 



In considering the further development of the Aphidinae, a more 

 or less distinct development of the cornicles and antennal tubercles is 

 found. There are thus two types which separate themselves, rep- 

 resented by Aphis and Macrosiphum respectively. These may be 

 considered as leaving the aphid line at about the same time after the 

 development of prominent cornicles. There are, consequently, two 

 subtribes, the Aphidina and the Macrosiphina. The Cervaphidina 

 represents a group of insects armed with long, somewhat cylindric 

 cornicles, and very prominent spinelike protuberances. The number 

 of antennal segments is somewhat reduced, as is also the wing vena- 

 tion. It seems evident then that this is a subtribe on somewhat the 



