324 FRED. V. THEOBALD — 



hairs in front ; antennae not as long as the body, the first three segments dark 

 brown, the fourth and fifth with a broad pale band on the basal half, sixth brown, 

 the first segment is wider and slightly longer than the second ; the third the 

 longest, with from 10 to 14 sensoria showing marked double contour lines, along 

 the whole length of the segment, and with five prominent pale brown hairs on 

 one side, and three on the other side, imbricated ; fourth segment slightly shorter 

 than the third, showing one sensorium in the middle ; fifth shorter than the fourth, 

 with a large subapical sensorium ; sixth slightly longer than four and five, with 

 one large and six small sensoria at the base of the flagellum ; all the segments 

 imbricated and with a few hairs. Eyes dark. Rostrum pale at base, dark at 

 apex, with a few hairs, reaching to the second pair of legs or a little beyond. 

 Cornicles black, moderately loug and thick, slightly expanding basally, 

 imbricated along their whole length. Cauda black, about half the length of the 

 cornicles, bluntly rounded at the apex, with many long thin pale hairs. Legs 

 moderately long, femora rather thick and dark, tibiae long and narrower, with a 

 narrow dark band at the base and a wider one at the apex : tarsi dark, of two 

 segments, hairy, imbricated. Wings with yellowish brown veins and stigma, some 

 browner than others, longer than the body. Length 1'6 to 2 mm. 



Apterous viviparous female. — Dark brown ; two basal segments of antennae 

 dark brown, rest paler brown, third segment the palest. Legs with dark femora, 

 tibiae widely black at the apex, tarsi black, legs shorter and thicker than in the 

 alate female, hairy. Cauda and cornicles dark. Antennae not quite as loug as 

 the body ; the first segment wider and longer than the second, which is partly 

 sunk into it ; the third slightly longer than the fourth ; the fourth slightly 

 longer than the fifth ; the sixth slightly longer than four and five ; a single 

 sensorium near the apex of the fifth and one large and six small at the base of 

 the flagellum ; all the segments imbricated, and each with a few hairs. Cauda 

 rather more than half the length of the cornicles, with many long fine pale hairs ; 

 cornicles black, imbricated. Head convex, with several long pale hairs. A 

 lateral tubercle on each side of pro thorax and five (6?) pairs of small short dark 

 tubercles behind. Cuticle with hexagonal ornamentation. A few hairs on the 

 body. Lenytli 1*5 mm. 



Oviparous female (?). — Similar to the foregoing, but the third, fourth and fifth 

 antennal segments pale. Legs similar, but the posterior tibiae much thickened ; 

 head slightly convex. Length 1*10 to 2 mm. 



Nymph. — Similar to apterous female, but the cauda shorter and the wing-buds 

 dark. Head slightly rounded in front. 



Portuguese East Africa : Zambezia (Tavares) ; Nyasaland : Blantyre, 

 vi. 1910 (Dr. J. E. S. Old) : Brit. East Africa :. Njoro (T. J. Anderson); 

 Zanzibar : 3. iii. 1911 (Dr. W. M. Aders). 



Food-plants : Citrus trees and Cotton. 



Del Guercio describes and figures a black citrus aphis from the Zambesi 

 region as Aphis tavaresi, but the description is not at all full. However the 

 general appearance of the citrus aphides sent from Blantyre and Njoro agree so 

 closely that I feel sure they must be the same species. The figures given by 

 Del Guercio do not seem normal, the cornicles are much constricted at the apex ; 

 this occurs in some few of the spirit specimens I have seen. The species is 



