56 



naturally suppose, would gradually succumb and die during winter, 

 but this does not appear to be the case. Eepeated examinations of 

 certain plants from the time the last migrants appeared on the trees 

 till some time in February the following year, both outdoors and in hot- 

 houses, even after several severe frosts and snowstorms, showed the 

 lice on all the plants in large numbers in every stage of development, 

 and among them often many winged ones as lively and active as though 

 the weather had been most agreeable to them. 



It may be well to state, however, that the only season in which this 

 observation has been made was that of 1888-89, in which the winter 

 was a remarkably open one. The lice have not been searched for during 

 other and more severe winters. 



DESCRIPTIONS OF THE DIFFERENT STAGES. 

 FIRST GENERATION ( STEM-MOTHER). 



First stage. — Length of recently hatched larva, about 0.6 mm. ; color almost black, 

 with a slight greenish tinge ; antennas five-jointed, the fifth somewhat longer than the 

 third; joints 1, 2, and 4 shortest and subequal in length; frontal tubercles wanting; 

 legs very stout, nectaries about as long as thick, and apparently somewhat shorter 

 than the second antennal joint. 



Second stage. — Length, about 0.8 mm. ; color darker or paler greenish-gray, with 

 a slightly darker medio-dorsal line; head and all members darkest; the head some- 

 what polished, with a distinct and quite deep fovea on the vertex; antennas still 

 five-jointed, the third joint as long or somewhat longer than the two last together, 

 with an indication of a division into two joints; frontal tubercles still wanting; 

 rostrum shorter than the body; nectaries slightly longer than thick, with a con- 

 striction or annulus at extreme tip. 



Third stage. — Length, about 1 mm. ; color either greenish-gray, greenish, or 

 greenish-yellow, medio-dorsal line darkest, while the lateral margin and end of 

 body are often slightly ferruginous ; the dorsum is also frequently marked with faint 

 but darker irregular green mottlings ; head darker or lighter dusky, x>olishe;l, and 

 with a paler median line; antennas six-jointed, dusky, joint 3 palest at base; the 

 third and sixth longest, about equal, or the sixth is slightly longest ; the fourth and 

 fifth subequal, each rather less than half the length of the sixth; eyes almost black; 

 legs still stout, though more slender than in previous stages; femora and tibia?, 

 somewhat dusky toward the end; tarsi blackish; body almost oval, broadest at 

 the middle of the abdomen ; nectaries at least twice as long as thick, reaching to 

 tip of abdomen, slightly curved, and somewhat thinnest a short distance above base; 

 apex dusky, the constriction as before. 



Fourth stage: — Length, 1.4 mm. ; general color, greenish-yellow, marked more or 

 less distinctly on the head, dorsum, and lateral margin with crimson or pinkish spots ; 

 head faintly concave in front, with a slight median swelling; antennas very similar 

 in the proportions of their joints to those of the previous stage, though longer and 

 more slender, greenish, with the tip of joints 3 and 4 and the two last joints black- 

 ish ; eyes brown ; rostrum rather short, reaching to about the median legs ; legs of 

 color of body, with about their terminal third dusky ; tarsi blackish ; body oval, 

 tapering to a point posteriorly, and distinctly filled with almost fully developed 

 pseudova; nectaries rather slender, slightly curved, almost of equal thickness, 

 slightly stoutest at base, four to five times longer than thick, faintly dusky, darkest 

 at tip ; tail not yet present. 



Fifth stage. — Length, 1.6 to 1.8 mm.; general, color pale greenish-yellow, with a 

 more or less distinct darker green medio-dorsal line, marked along the lateral border 



