206 NEW YORK STATE MUSEUM 



enou_i,fh and are carried away on the falling leaves and scattered by the 

 winds. The winter is passetl as partly grown insects which are c|uite 

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

 The first warm weather in s|)riiig brings signs of activity. Early in April 

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

 travel considerable distances before establishing themselves; this is 

 special!)' true of the males, which are quite aj)t to spin cocoons on dead 

 twigs, lloneydew 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 numlxrs 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 apj^earance of the female. Her form changes from eliptic [pi. 3, 

 fig. 14 I to oval I pi. 3, fig. 16 1 and the secretion of the wax is much more 

 copious and is mainl\- from tlic lateral spines insteatl of from both lateral 

 and dorsal, as occurred in the fall. 



This bark louse, like the elm leaf beetle, a|)pears to thrive best on the 

 luiro])fan s])ecies of I'linus, specially the Scotch elm. 



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

 young trees and it is untloul)leill\- in this wa\- that it has succeeded in 

 establishing itself at thi- wi(.lel\- separatetl ])oinls naini-d aljove. Its rapid 

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

 particularly the English sparrow. There appears to l)e no other adecpiate 

 e.xplanation of the geni-ral occurrence of this pest throughout .Mbany 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, com|)ared 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 i)robable that a number of lad)beetles in 

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

 insect. The two spotted ladybeetle. Ad alia I1 i ]i u n c t a t a Linn., has 



