THE MEALY PLUM APHIS. 13 



The young were produced within about 12 days (in the cages mostly 

 within 7 days) and at a rate of from 2 to 3 a day. The migrants, 

 after they had extruded their complement of young, remained settled 

 for as long as two weeks. 



MALE AND OVIPAROUS FEMALE. 



Male. 

 description. 



Pupa. — Noticeably smaller than that of the fall migrant, light yellow in color ; 

 eyes dark red ; tarsi and distal antennal joint dusky gray. Form elongate. 



Adult. — Light clay yellow; head, antennae, prothorax, thoracic lobes, scutel- 

 lum, legs, cornicles, and style brownish-black ; eyes dark red ; stigma light green- 

 ish-gray ; veins of wings brown ; abdomen with a dorsomedian longitudinal row 

 (segments 1 to 5 inclusive) of subcircular gray spots, similar lateral spots on 

 segments 1 to 3 inclusive, and with cross bars of similar color on segments 6, 7, 

 and 8 ; genital plate and organs dark gray ; beak pale yellow, tip brownish black. 

 The male is almost devoid of " meal." 



Antenna? on gibbous frontal tubercles, three-fourths the length of the body ; 

 comparative measurements as follows : I, 0.08 mm. ; II, 0.07 ; III, 0.38 ; IV, 0.25 ; 

 V, 0.23; VI, 0.46 (0.09 plus 0.37). Wings 2.3 mm. long. Cornicles vase-shaped, 

 narrowed close to base, faintly imbricated, 0.085 mm. in length. Style conical, 

 0.10 mm. long. Beak reaching a little beyond anterior mesosternal border, 0.30 

 mm. long. Length of body, 2.05 mm., width, 0.68 mm. 



Circular sensoria are distributed along the antennal joints much as in the 

 spring and fall migrants. They are much more numerous, there being from 38 

 to 53 on III, 19 to 29 on IV, 9 to 18 on V, and the usual apical group on VI. 



Oviparous Female. 

 description. 



Neivly hatched. — Light green, appendages hyaline; eyes red. Form oval. 



The immature females are bright green with a very scant covering of " meal." 



A dult.— Greenish yellow; eyes dark red; distal half of antenna?, cornicles, and 

 tarsi gray ; beak pale yellow, tip brown. The coating of " meal " is not so 

 conspicuous as in the earlier forms, in this respect resembling the stem mother. 

 Form elongate oval, rather flat. 



Antenna? not quite half as long as body, comparative measurements as fol- 

 lows : I, 0.06 mm.; II, 0.035; III, 0.145; IV, 0.06; V, 0.085; VI, 0.245 (0.05 plus 

 0.195). Beak reaching second coxa?, 0.25 mm. long. Cornicles cylindrical, twice 

 as long as wide at base, faintly imbricated, 0.05 mm. long. 



Style conical, 0.08 mm. long. Length of body, 1.18 mm. ; width, 0.52 mm. 



The thickened hind tibia? bear a large number of small circular sensoria. 



Nymphal Stages. 



For the male the nymphal stages were not observed closely, this 

 form having been very rare on the cat-tails in 1916. From such 

 observations as took place it appears safe to say that both males and 

 fall migrants develop in about three weeks. The development of ovip- 

 arous females was observed in 1916 on both Agen (French) prunes and 



