I 78 NEW YORK STATE MUSEUM 



brimtul of struggling plant lice and particles of whitened honeydew. It is 

 occasionall)' abundant enough to cause considerable damage, though as a 

 rule, the disfigurement of the tree and the shrubs below constitute the 

 principal nuisance. 



Life history. The life history of this species has been carefulh- worked 

 out by the late Professor Riley, who states that the over-wintering egg is a 

 minute, dull yellowish, ovoid object about ■ ;o inch long, which is deposited 

 in cracks and crevices of the bark durmg the summer. This remains 

 dormant till the leaf buds begin to swell, at w-hich time the young plant 

 lice issue, crawl to the terminal leaves and branches and settle on the first 

 tender leaflet they find. This is the first generation or stem mothers, and 

 they establish themselves on the under surface of the leaf and very soon 

 cause it to swell and curl, usually from one edge. The curl varies however, 

 depending somewhat on whether one or several stem mothers settle on the 

 same bud. The stem mother, at first pale yellowish reel, with dark append- 

 ages, increases rapidly in size, depending somewhat on the nourishment in 

 the leaf. In about 25 days young begin to appear at the rate of about one 

 to every six or seven hours, according to temperature. The colony 

 increases in numbers and early in June in this latitude, the affected leaves 

 may be literally overflowing with plant lice and the honeydew they produce. 

 In favorable years the lice soon become so abundant that the leaves do not 

 protect them, and are covered with multitudes of old and young, some 

 wingless and others with organs of flight. At this time the second genera- 

 tion of wingless mothers are surrounded by smaller colonies, all of which in 

 turn acquire wrings. Other generations are produced, as many as six 

 occurring in one season, the last depositing eggs in the crevices of the bark 

 as mentioned above. 



Dr Riley states that this species is very closely allied to the European 



S. u 1 m i Linn. 



Bibliography 



1880 Riley, C. V. & Monell, J. U. S. Geol. Geog. Sur. Bui. 5, p. 4-9 



