PERGANDE NORTH AMERICAN PHYLLOXERINiE. 255 



Hence there are but three annual generations produced, viz., 

 the apterous and parthenogenetic stem-mother, the migratory or 

 winged sexuparse and the apterous sexed individuals ; and all the 

 direct issue from the stem-mother become sexuparse. This, as 

 already stated, may be looked upon as the normal mode of the 

 development of the majority of the gall-producing species on 

 Hickory. Yet there are exceptions, and our Hicoria species pre- 

 ■ sent some of the varying biologic features already known in other 

 species of the sub-family and have, in addition, others which are 

 peculiar. 



Stem -MOTHER. — Recently hatched. Length 0.3™"-. Color 

 yellow. Eyes reddish-brown with a clear, colorless ocellus at 

 their middle. Antennae, legs and rostrum dusky, the last joint of 

 the rostrum yellow. Body elongate-ovoid. Antennae stout, the 

 terminal joint with apparently five annulations and with a thumb, 

 externally, near tip. Tarsi with strong claws and digituli. The 

 rostrum stout, reaching a little beyond the posterior margin of 

 the metasternum. 



Mature stem-mother. — Length o.8-i"™-; diameter across 

 mesothorax o.6™'"-- Shape broadly pyriform, broadest across the 

 mesothorax. Color grayish-green or yellow, with the sutures 

 slightly darker. Antennae and legs blackish. Surface of the 

 body densely covered with minute, pointed granules. Front of 

 head somewhat concave, lined with four short and rather stiff 

 bristles. Antennae short, joint 3 about twice the length of the 

 others combined, of uniform thickness, slightly curved and quite 

 coarsely scaly ; the thumb short, very distinct, inserted just below 

 tip. Legs and rostrum stout, the latter reaching to middle coxae. 

 The eggs deposited by the stem-mother are quite transparent, 

 highly polished, without any sculpturing, and faintly yellowish 

 or greenish. 



Pupa. — Length about i™'°-, diameter across mesothorax 0.4™™-. 

 Color orange, lemon-yellow or yellowish-green, the thoracic seg- 

 ments darkest. Antennae, legs, rostrum and wing-pads more or 

 less dusky. Eyes and ocellar spots red. Dorsal surface closely 

 and curiously sculptured, being covered with minute, slightly 

 dusky warts, which terminate either in one or often in as many 

 as five or six small scale-like points, these again often provided 



