452 Mr. F. Walker's Descriptions of Aphides. 



lar, Populus dilatata, and of the willow-tree, Salix alba, vitellina 

 and caprea ; it is fixed there in dense masses, and each row over- 

 laps the one below it. Large companies of ants {Formica rufa) 

 are continually passing up and down the trunks of the trees 

 whereon it is stationed. The body is oval, rather flat, hairy, and 

 of a very dull yellow colour, and thickly covered with gray pow- 

 der : the front is broad and slightly convex : the feelers are seta- 

 ceous, hairy, and much less than half the length of the body ; 

 their tips are dark brown ; the fourth joint is less than half the 

 length of the third ; the fifth is full as long as the fourth ; the 

 sixth is little more than half the length of the fifth ; the seventh 

 is much longer and more slender than the sixth : the mouth 

 reaches the hind hips ; its tip is dark brown : there are six rows 

 of dark spots along the back : the nectaries are yellow, and not 

 more than one-twentieth of the length of the body : the legs are 

 stout and rather hairy ; the fore-legs are much shorter than the 

 hind-legs ; the feet, and the tips of the shanks and of the hind- 

 thighs are dark brown : the body contains about twenty young 

 ones of various size. 



The viviparous winged female. This has much resemblance to 

 the viviparous wingless female : the sixth joint of the feelers is 

 much less than half the length of the fifth : the discs of the head, 

 of the chest, and of the breast are dark : the wings are colourless, 

 and of moderate size ; the veins and the brand are tawny ; the 

 rib-veins widen into irregularly spindle-shaped brands soon after 

 the middle of the fore-border of the wing ; the first branch-vein 

 is nearly straight ; the second is slightly curved ; the third is in- 

 clined inwards, and forms two angles as usual ; its first fork begins 

 after one-third, and the second at two-thirds of its length ; it ap- 

 proaches very near its source before it becomes obsolete. 



Length of the body 1^ line; of the wings 3 lines. 



It is infested by an Aphidius, and is also devoured by the 

 grubs of a Syrphus and of an Agromyza. 



24. Aphis Salicis. 



Aphis Salicis, Linn. Syst. Nat. ii. 736. 26 ; Faun. Suec. 995 ; 

 Gmel.ed. Syst. Nat. i. 2207. 2210; Fabr. Syst. Ins. ii. 389. 46; 

 Ent. Syst. iv. 219. 47; Syst. Ehyn. 301. 47; Reaum. Ins. iii. 

 281-350. t. 22. f. 2; Deg. Ins. iii. 50. 11; Schrank, Faun. 

 Boic. ii. 1. 102. 1176; Rossi, Faun. Etrusc. 264. 1398; Kalt. 

 Mon. Pflan. i. 131 . 100 ; Ratz. Forst. Ins. iii. 218. 18. 



Salicifex, Amyot, Ann. Soc. Ent. Fr. 2 me serie, v. 480. 



The viviparous wingless female. Dull green, covered with white 

 powder, rather flat, and increasing in breadth from the head till 

 near the tip of the abdomen : there is a row of black spots on 

 each side of the body : the sides are dull orange, and so disposed 



