PERGANDE NORTH AMERICAN PHYLLOXERIN^. 



199 



obsolete. Stigma distinct. The stigmal vein straight and normal 

 in its course, exhibiting no tendency to connect with the discoidal 

 vein. 



Phylloxera intermedia Pergande, n. sp. 



PI. II, figs. 11-14; PL X., figs. 64-65. 



The gall of this species appears to be intermediate between Ph. 

 c. -septum and Ph. pida. Its inner construction resembles that of 

 c. -septum on account of the presence of a rudiment of the central 

 membrane, though its general form, especially in the larger 

 specimens, is more like that of picta, from which, however, it 

 differs in the much thicker walls and the absence of a nipple on 

 the upper side. 



The transverse diameter of this gall varies between 3 and 6"™- 

 and its vertical diameter between 2 and 3™'"-. The shape above is 

 regularly convex in the larger galls and slightly conical in the 

 smaller ones, and without a trace of a nipple or opening before 

 maturity. On the under side it projects but slightly and is 

 provided with a minute, but closed nipple, the insect issuing from 

 the upper' surface which splits in a more or less jagged, round or 

 oval opening, the bracts of which curve more or less outward. In 

 some few cases the nipple on the under side also opens sufficiently 

 to allow the insects to emerge from both sides. The color of the 

 galls above is reddish or yellowish, generally surrounded by a 

 paler ring, and beneath paler than the leaf. It occurs on Hicoria 

 alba in company with the other two, and matures from the end of 

 May to the middle of June. 



Migratory Female. — I^ength of body 08.-1.3'"™-. Expanse 

 1.6-2.4"""- Color pale orange, palest toward the end of the 

 body, the prothorax darkest. Head, antennae and legs dusky, 

 the metathorax and scutellum darker, the sternal plate black. 

 The prothorax is more or less distinctly marked, mediodorsally, 

 with a small, transverse, dusky spot and bordered each side with 

 a dusky shade. Antennae rather more slender than in the other 

 two species, about as long as the tibiae and apparently composed 

 of four joints, the third joint in most of the specimens being dis- 

 tinctly and sharply divided just above the lower sensorial 

 membrane. The annulations are rather shallow and in some 

 Specimens difficult to detect. There is, however, more or less 



