206 NEW YORK STATE MUSEUM 



enough and are carried away on the falling leaves and scattered by the 

 winds. The winter is passed as partly grown insects which are quite 

 well protected by a waxy secretion from the dorsal and lateral processes. 

 The first warm weather in spring brings signs of activity. Early in April 

 the females molt and the males form their cocoons. At this time many 

 travel considerable distances before establishing themselves; this is 

 specially true of the males, which are quite apt to spin cocoons on dead 

 twigs. Honeydew is excreted by the females in very large quantities 

 from this time till the young appear in July. This is evidently the period 

 when the insect is most injurious. The wingless males or pseudimagos 

 were present in large numbers May lo, 1900, while the perfect males were 

 not abundant till May 21 and there was a time between these dates when 

 no males could be found. .Soon after pairing there is a marked difference 

 in the appearance of the female. Her form changes from eliptic [pi. 3, 

 fig. 14] to oval [pi. 3, fig. i6j anci the secretion of the wax is much more 

 copious and is mainly from the lateral spines instead of from both lateral 

 and dorsal, as occurred in the fall. 



This bark louse, like the elm leaf beetle, appears to thrive best on the 

 European species of Ulmus, specially the Scotch elm. 



Means of distribution. This insect can be carried long distances on 

 young trees and it is undoubtedly in this way that it has succeeded in 

 establishing itself at the widely separated points named above. Its rapid 

 dissemination throughout a city is probably due to the agency of birds, 

 particularly the English sparrow. There appears to be no other adequate 

 explanation of the general occurrence of this pest throughout Albany and 

 Troy. It is also possible that the young falling with the leaves are blown 

 to new localties and succeed in establishing themselves on uninfested trees. 

 This latter means is so uncertain, compared with birds which habitually fly 

 from tree to tree, that it can not be considered as a source of much danger. 

 Natural enemies. It is very probable that a number of ladybeetles in 

 both adult and larval condition feed to some extent on the young of this 

 insect. The two spotted ladybeetle, Ad alia bipunctata Linn., has 



