﻿APHIDIDAE OF SOUTHERN CALIFORNIA III 



E. O. ESSIG. 



Chaitophorus populicola Thos. (?) 



Winged Viviparous Female: (Fig. 44 A) — Length 1.38 mm., width 

 0.5 mm., wing expansion 2.7 mm. Prevailing color, nearly black with yellow 

 membrane. Head, slightly narrower than thorax, much wider than long, and 

 hairy. Compound eyes, coarsely granulated, red, with terete tubercles just 

 behind the outer margin. Antennae, (Fig. 44 G) do not arise from frontal 

 tubercles, two-thirds as long as body, 6-articled. The color and length of the 

 respective articles are as follows : I 0.06 mm. dark, II 0.06 mm. dark, III 0.26 

 mm. yellow, IV 0.15 mm. yellow with dark distal end, V 0.12 mm. dark, VI 0.2 

 mm. dark. Distribution of sensoria: I and II none. III many large circular, 

 IV several large circular in row, V one large circular at distal end, VI several 

 marginal in the nail-like process. All the articles are hairy. Pro-thorax, 

 without lateral tubercle, hairy. Rostrum, reaches to metathoracic coxae. Ab- 

 domen, distinctly segmented, hairy or spiny. Cornicles (Fig. 44 C) cylindrical 

 and pale yellow. Legs, moderately long and hairy. Color, dark near body 

 and at tips, light near the middle. Wings, clouded along the veins. Primary, 

 length 1.1 mm., width 0.33 mm. Cubitus, hairy near the stigma. Stigma, long 

 and rounded at apex, very dark. Radius, well curved. Obliques, first straight, 

 second curving slightly out, third curving and twice-forked. Secondary, slight- 

 ly clouded, length 0.7 mm., width 0.2 mm. Sub-costal, extends to wing tip. 

 First discoidal, rudimentary, does not connect with the sub-costal, short and 

 straight. Second discoidal, does not connect with the sub-costal, nearly twice 

 as long as first discoidal, curves slightly outward. Style, rounded, hairy, 

 Cauda, obscure. 



Apterous Viviparous Female: (Fig. 44 E) — Length 1.4 mm., width 

 0.8 mm. Diflfers from the winged form in the following : Body is more 

 robust and is extremely hairy or spiny. Prevailing color, reddish brown with 

 light yellow marking on the back. Antennae, sensoria are distributed as fol- 

 lows: I, II, III, IV, none; V, one circular near the distal end; VI, several 

 small marginal in the nail-like process. Antennae (Fig. 44 F). Cornicles 

 (Fig. 44 C). 



Nymph of Apterous Viviparous Female: (Fig. 44 B) — The first-born 

 are extremely small — almost microscopic. Color, pinkish. Antennae (Fig. 

 44 D) usually four-articled, half as long as the body, with sensoria as follows: 

 I, II, none; III, few circular; IV, small marginal in the nail-like process. All 

 articles are slightly hairy. Abdomen, distinctly segmented with hair or spines 

 in definite rows on the back, usually six. Rostrum, nearly as long as the body. 



This aphid is found in considerable numbers on the young stems of 

 Populus trichocarpa in the Santa Clara River Valley near Santa Paula. 



While in general it conforms to the general description of Chaitophorus 

 populicola by Thomas, yet the yellow marking on the back of the apterous 

 female is more triangular than y-shaped. In no case has it been found on the 

 leaves of the tree. 



