1064 WALTER H. WELLHOUSE 
trees. During the summer of 1919 the writer saw a small Crataegus prui- 
nosa tree killed and a very large C. punctata tree almost entirely defo- 
liated due to the sucking of sap by myriads of these aphids. They are 
rather large, yellowish green aphids, with long cornicles, and their most 
easily recognizable character is the presence of four dark green spots 
arranged in a rectangle on the dorsal side of the abdomen (fig. 108). The 
entire life history is passed on Crataegus trees. The black winter eggs 
are placed on the twigs and the smaller branches. They begin to hatch 
in May, after the leaves are well opened. The young aphids move to the 
lower surface of the leaves, and their feeding, as the colony increases, causes 
the leaves to curl downward. 
In late June an alate brood appears and migrates to near-by branches 
or trees to start new colonies. It is after this brood appears that the species 
becomes so injurious. 
crataegifoliae Fitch, Aphis 
In early May, 1918, the Crataegus coccinea trees at Ithaca began to show 
the terminal rosettes of curled leaves caused by Aphis crataegifoliae. The 
rosettes turned red, and the aphids w ulin ete ‘also were red. The infested 
branches remained de- 
formed and somewhat 
stunted throughout the 
season, although the 
aphids departed from the 
trees about May 20 to 
seek leguminous hosts. 
No aphids of this species 
were observed the next 
year. 
lanigera Hausm., Erio- 
soma (Woolly aphis) 
The woolly aphids first 
become noticeable in 
early June as small white 
spots on the tender twigs 
of Crataegus. In a favor- 
able season such as the 
summer of 1918, they be- 
come very conspicuous 
and cover entire branches 
by late summer fig. 109). 
The writer has not found 
the roots of Crataegus 
Fra. 109, ERIOSOMA LANIGERA ON HAWTHCGRN infested, 
