October, '08] JOURNAL OF ECONOMIC ENTOMOLOGY 303 



I am specially indebted to Mr. L. C. Bragg and Mr. E. P. Taylor 

 for many of the life-history and food-plant records, and Miss M. A. 

 Palmer has made all the drawings for the illustrations. 



APHIDS INFESTING APPLE AND PEAR TREES 



The Green Apple Aphis, Aphis pomi, DeGeer ; Plate 5, figs. 1-8. 



Some of the More Important Literature 



Aphis pomi, n. sp. DeGeer, Memoires, III, 1773. 



Aphis pyri mali. Fab. Systeuia Eutomologica, 1775. 



Aphis mall, Kaltenbach, Mon. cler Fam. Pflanzenlouse, p. 72, 1843. 



Aphis mali, Koch, Die Pflauzenlouse, p. 107, 1857. 



Aphis mali, Buckton, Mon. British Aphides, II, p. 44, 1879. 



Aphis mali, J. B. Smith, Bull. 143, N. J. Exp. Sta., 1900. 



Aphis padi, Sanderson, 12th Rep. Del. Exp. Sta., p. 191, 1901. 



Aphis pomi, Sanderson, 13th Rep. Del. Exp. Sta., p. 130, 1902. 



Aphis mali, Quaintauce, Circular 81, Bureau of Ent., 1907. 



Eggs — The eggs vary little from .60 mm. in length by .26 mm. in trans- 

 verse diameter. When first deposited, they are light green in color, but in 

 the course of a few days change to deep polished black. They are scattered 

 promiscuously over the smooth bark of the twigs. Upon hatching the shell 

 splits longitudinally at one end, as shown on Plate 6, Fig. 20. Hatching 

 begins several days before the apple buds open at all, or with the opening of 

 the earliest apricot blossoms in the same neighborhood. 



Young Stem-mother — Plate 5, fig. 1. 



The young stem-mothers, before the first molt, are very dark green in gen- 

 eral color; antennae and legs dusky yellowish green; cornicles very short and 

 black; antennae stout, 5-jointed,^ and with sensoria at the distal ends of joints 

 3 and 4. Length of body, in specimens described, .GO mm.; length of antennae 

 .28 mm. From eggs taken at Paonia, Colorado, on appl^, March 2, 1907. 



Adult Stem-mother— Plate 5, fig. 2; and plate 6, fig. 1. 



From the same source as the preceding and hatched and reared in the 

 insectary, probably a little under size. 



Color a bright green with a little tinge of yellow, head moi'e or less con- 

 spicuously dusky brown; cornicles, cauda, eyes, base and tip of beak, tarsi, 

 distal portions of tibiae, and antennae, the knees and genital plates, black or 

 blackish; remaining portions of legs and antenna? a little dusky. The lateral 

 thoracic tubercles are present, and similar ones occur on part or all the ab- 

 dominal segments to the 7th; cornicles nearly straight and gradually tapering 

 to their distal ends. The antennae are short and G-jointed, as is usually true 

 with stem-mothers in this genus. The third joint is very much the longest 

 (Plate 6. fig. 1) and is really the union of joints 3 and 4. Sometimes the 

 suture is present, cutting this joint into two. Length of body varying little 

 from 1.50 mm.; width, .80 to .90 mm.; antenna, .75 mm.; antenna joints: 

 three, ,26 mm.; four, .13 mm.; five, .11 mm.; six, .14 mm.; cornicles, .25 mm. 



Young of Stem-mothers — Plate 5, fig. 4. 



'For convenience I shall refer to the flnfrelliiin of the last joint of the antenna as 

 a separate joint. 



