PLUM INSECTS 



263 



small, delicate, white-winged males appear and soon after 

 mating perish. During the latter part of May or in June the 

 female lays a large number of minute, white eggs which com- 

 pletely fill the cavity beneath tlie scale previously occupied 

 by her body (Fig. 227). Over 2000 eggs have been counted 

 beneath a single scale. They hatch in al)out a month and the 

 minute young lice crawl out on to 

 the leaves and establish themselves 

 along the principal veins. Infested 

 leaves become curled and turn yel- 

 lowish, the tree makes but little 

 growth and the fruit remains under- 

 sized or falls prematurely. The 

 young scales collectively produce a 

 great quantity of a clear sweet liquid 

 known as honey-dew, which in the 

 absence of heavy rains collects on 

 the leaves and fruit and serves as 

 a medium for the growth of a fungus 

 which gives the tree a smutty, dis- 

 gusting appearance. During September most of the scales 

 abandon the leaves and seek winter quarters on the bark of 

 the tree, mostly on the smaller branches, but a small per- 

 centage fall with the leaves and probably perish. 



Treatment. 



Commercial plum growers have found little difficulty in 

 controlling this scale by one or two thorough applications of 

 kerosene emulsion, diluted with 4 or 5 parts of water, applied 

 while the trees are dormant. Miscible oils at the usual winter 

 strength can also be used to advantage. 



Fig. 229. — Hibernating 

 scales on plum of the European 

 fruit Lecanium. 



References 



Cornell Agr. Exp. Sta. Biill. 83. 1894. 



Cornell Agr. Exp. Sta. Bull. 108, pp. 82-80. 1896. 



