750 Rospert MATHESON 
The egg is oval in form, and is slightly flattened on the side next the bark. 
The length is from 0.48 to 0.56 mm. The color is identical with that of 
the egg of Aphis pomi. 
THE APPLE-BUD APHIS, OR OAT APHIS 
(Aphis avenae Fabricius) 
The apple-bud aphis has been present in orchards in the eastern United 
States since the early part of the past century. It has been confused 
constantly with the two preceding species, Aphis pomi De G. and A. 
' sorbt Kalt., and in many eases it is difficult if not impossible to determine 
to which species a writer is referring. It is not purposed in this article 
to present a detailed historical account of this species, inasmuch as this 
plant louse is a more serious pest of its summer host plants than of apple. 
However, it may be well to summarize briefly the synonymy of the 
species as 1t occurs in literature. This, according to the writer’s views, 
is as follows: 
1794 Aphis avenae Fabricius, Ent. Syst. 4 : 214. 
1851 Aphis mali Fitch, Cat. Ins. Cab. Nat. Hist., p. 65. 
1855 Aphis mali (in part) Fitch, Trans. N. Y. Agr. Soc. 14: 753. 
1886 Aphis annue Oestlund, Geol. and Nat. Hist. Surv. Minn., Ann. Rept. 14 : 43. 
1887 Aphis annue Oestlund, Geol. and Nat. Hist. Survey Minn., Bul. 4: 66. 
1902 Aphis fitchit Sanderson, Del. Agr. Exp. Sta., Ann. Rept. 13 : 137. 
1904 Siphocoryne avene Pergande, U. 8. Div. Ent., Bul. 44: 5. 
1917 Aphis prunifolie Baker, Science (n. s.) 46 : 410-411. 
NATURAL HISTORY 
The bionomics of this plant louse have been studied by a number of | 
writers. The following account deals only with its life history and habits | 
in relation to the apple, its primary host plant. 
The eggs of Aphis avenae, like those of the two species already discussed, 
are laid in the autumn on apple, and at Ithaca hibernation takes place 
in this stage tho the writer has found the species hibernating as wingless_ 
viviparous females about the base of its summer food plants. Whether 
it can succeed in living thru northern winters and continuing its activities 
in the spring has not been accurately determined. 
The eggs begin hatching in the spring from a week to ten days earlienl| | 
than those of the green apple aphis or the rosy apple aphis. In the past} 
three years the first eggs hatched on April 19 (1916), April 17 (1917),} 
