Siphocoryne avense Fab. 



Aphis avenx Fab., Entoruologia Systematica, Vol. IV, p. 214, 1794. 



Aphis mall Fitch, First and Second Reports on the Noxious and Beneficial Insects 



of New York, p. 49, 1856. 

 Aphisprunifoli.se Fitch, First and Second Reports on the Noxious and Beneficial 



Insects of New York, p. 122, 1856. 

 Aphis avenx Fitch, Sixth Report of the Noxious and Beneficial Insects of New 



York, p. 91, 1856. 

 Siphonophora avenx Thomas (in part), Eighth Report, Noxious and Beneficial 



Insects of Illinois, p. 52, 1879. 

 Aphis annuse Oestl., Synopsis of the Aphididae of Minnesota, p. 66, 1887. 

 Aphis fitchii Sanderson, Thirteenth Annual Report Delaware College, Agricultural 



Experiment Station, p. 137, 1901. 



DESCRIPTION OF THE SPECIES. 



Winter egg. — The hibernating or winter eggs are deposited during the months of 

 October to December on the trunk and branches of the apple; pear, quince, haw- 

 thorn, and plum, under loose bark, in cracks, depressions, in the crotches, and around 

 the buds, where they remain dormant until the following spring. They are about 

 0.6 mm in length, pitch black, and highly polished. In favorable years they become 

 frequently so numerous as to cover entire branches, when they may be readily 

 observed. Yet, notwithstanding the great number of eggs, the majority, through 

 one cause or another, are destined to perish during the coming winter, when num- 

 bers of them are washed >ff by rains, sleet, or snow. 



Stem-mother; first generation. — The young larvse, hatching from these eggs, make 

 their first appearance, according to the advancement of the season, from about the 

 middle of March to the middle of April, at about the time that the buds commence 

 to burst. They are at that time about 0.6 mm in length, at first yellowish green, 

 though changing within a few hours to a rather dark green; the head changes to 

 dusky or almost black in front and the eyes to a dark brown. The legs are dusky, 

 rather stout, and somewhat hairy. The antennas are short and four jointed, with the 

 third and the spur of the fourth much the longest and subequal in length. The 

 nectaries are very short and tuberculiform, while the rostrum reaches almost to the 

 end of the body. Within about a month after hatching they reach maturity. The 

 mature stem-mother measures about 1.4 mm in length, by almost one-half of it in 

 diameter about the middle of the abdomen. They are now of a greenish-yellow 

 color, with the medio-dorsal line dark green, while the head,, the first three joints of 

 the antenna?, the greater part of the legs, the lateral border and incisures of the 

 abdomen are rather pale. The remainder of the antehme, sometimes also the entire 

 legs and tail, are dusky and the eyes brown, while the nectaries are still paler than 

 the body, with the apex only dusky. All are covered with an extremely delicate, 

 pruinous secretion, which is often almost invisible above, though generally more 

 conspicuous on the under side of the body. The antennas are rather slender, about 

 one-half the length of the body and five jointed; the third joint is much the longest 

 and almost as long as the rest beyond it. The nectaries are quite slender, cylindrical 

 or somewhat stouter at base, though frequently with a slight indication of becoming 

 clavate toward the end, and with the apex more or less distinctly flaring; they reach 

 generally to or beyond the end of the body and are about as long as the spur of the 

 last antennal joint, The tail is elongate conical, about half the length of the 

 nectaries, covered with minute points and provided with a few bristles each side. 

 The last abdominal segment is semicircular, its edge lined with minute, acute teeth, 

 and fringed with a series of bristles. 



