Jan., 1908.] ' Notes on the Aphididae. I, 243 



NOTES ON THE APHIDIDAE. (I.) 



Observations on a Semi-aquatic Aphid, Aphis aquaticus n. sp. 



C. F. Jackson. 



This species is a typical representative of the genus Aphis, 

 and mav be characterized as follows: 



Winged viviparous female. Head broad, sparsely covered 

 v^ith hairs, two prominent hairs just above the median ocellus. 

 Eves black, prominent, the two lateral ocelli in proximity to 

 the two compound eyes; ocular tubercle large. Antennae reach- 

 ing slightly beyond thorax, joint I and II short. III nearly equal 

 to IV and V taken together, slightly imbricated, the posterior 

 margin bearing fifteen or more sensories. Joint IV slightlv 

 longer than V bearing three sensories and imbricated; V closely 

 imbricated with two or three sensories near distal end; joint VI 

 (including unguis or VII) longer than IV and V taken together; 

 the unguis very long and slender, at the base of which is a group 

 of six or seven sensories. Total length of antennae 1.6 mm.; 

 length of I, 0.08 mm. ; II, 0.08 mm. ; III, 0.39 mm. ; IV, 0.27 mm. ; 

 V, 0.23 mm.; VI, 0.14 mm.; VII, 0.46 mm. Beak stout, reach- 

 ing third pair of coxae. Thorax well developed, the pro-thorax 

 bearing a distinct lateral tubercle. Each thoracic segment has 

 on the ventral side a pair of small wax glands. Wings long and 

 narrow, with veins extending nearly to margin, the second branch 

 of the cubital not occuring until near the end of that vein. 

 Length of fore wing 3.1 mm.; width 1.1 mm.; length of hind 

 wing 1.3 mm., width 0.5 mm. Legs long, slender, tibia pro- 

 vided with four more or less regular row^s of long hairs. Fenjur 

 and tibia covered with a fine pulverulence. Abdomen ovate, the 

 second and eighth abdominal segments with distinct lateral tu- 

 bercles above wdiich is found a long bristle like hair. Honey- 

 tulSes 0.35 mm. long, nearly cylindrical or slightly vase-shaped. 

 Cauda conical, provided with two pairs of long recurved hairs ; 

 outer margin serrated. Length 0.12 mm. Anal plate provided 

 with six or eight pairs of long, curved hairs ; outer margin of plate 

 serrated. Color very variable, abdomen dark green, thorax 

 lighter tinged wnth ^^ellowish. Poorly fed individuals may be 

 very light, while old specimens maybe found of an almost uniform 

 black color. Total length of body 1.95 mm. Wing expanse, 

 7 mm. Immature resembling adult except that the thoracic 

 tubercle, wax glands and abdominal tubercles are much more 

 prominent, while the cauda does not appear until the third molt. 



Apterous viviparous female Head sparsely covered with 

 hairs, eyes black, prominent. Antennae reaching nearly to the 

 lioney-tubes ; joints I and II short, III but slightly longer than 



