The Aphididae of Nebraska I 5 



and pupae, and from these winged females were bred June 17. 

 My observations coincide with those of Oestlund, that the galls are 

 deserted by the insects during July and August. I have been 

 able to find the galls occupied in the latter month a few times ; 

 generally they are empty by the last of July. Some of the trees 

 in Lincoln and Ashland are so badly infested with these insects 

 that the large blackish galls render them very unsightly. The 

 insects seem to affect the same trees year after year. 



Specimens in collection of the University of Nebraska (nos. 

 10, 11) and of the U. S. National Museum (no. 129). 



12. Pemphigus walshii n. sp. 



Stem-mother: Globose, yellowish white. Head with top and front 

 black, below pale. Beak reaching almost to second coxae. Antennae 

 blackish, 4-jointed; I and II short and thick, III longest, cylindrical; IV 

 half as long as III, slender, cylindrical. Legs brown. Length of body 

 1.45 mm., width 1.07 mm., length of antennae 2 mm. Young stem-mother 

 yellowish white, antennae indistinctly 6-jointed. Beak reaching to or 

 beyond hind coxae. Tarsi 2-jointed. Abdomen covered more or less with 

 flocculent matter which is generally arranged in longitudinal rows of floc- 

 culent spots on the dorsum. Honey tubes appearing as circular openings. 



Winged form: Black. Head and thorax shining. Antennae black, reach- 

 ing beyond the tip of the thorax; III-VI conspicuously annulate, III with 

 21-25 rings* IV with 5-7, V with 8 and VI with 80 and a short claw bear- 

 ing on its tip 3 short, bristle-like hairs; I short and inconspicuous, II 

 short but broad, appearing almost spherical, III-IV cylindrical with rather 

 small articulations; III 0.2 mm. long, II 0.08 mm., V 0.80 mm., VI, includ- 

 ing claw, 0.12 mm. Wings large, roughened with minute scales; veins 

 slender, brown, first to second discoids originating near each other, the 

 first somewhat sinuate, the second straight till near the margin of the 

 wing when it curves gradually toward the body ; third discoid very slender, 

 the basal third obsolete (many specimens show a small bunch near the 

 margin of the wing). Subcostal heavy, smoky-bordered on its front 

 margin. Stigma whitish with a smoky, black posterior margin caused by 

 the continuation of the subcostal. Stigmal vein rather obtuse curved at 

 the basal third, then straight and the apical third recurved. Hind wings 

 with slender light brown veins. Two anterior pair of legs dark brown to 

 black with tibia and bases of femora paler, posterior pair all black; rather 

 small and slender. Tarsi distinctly 2-jointed and with long, slender claws. 

 Abdomen blackish pulverulent. Length of body 1 mm., to tip of wings 

 2 mm. 



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