5 



of Chicago, and no doubt thousands of the minute chalcids were killed, 

 as they were found quite plentifully on unsprayed trees. 



If it is necessary to resort to artificial means of control, as seems to 

 be the case in some sections, the spraying should be delayed until fall 

 or winter, when the Hyperaspis is hibernating at the bases of the trees 

 among lichens, moss or dried grass. Care s'nould be exercised in the 

 use of spray, and the bases of trees should be covered with canvas or 

 other suitable material to prevent the spray from running down the tree 

 trunks and collecting at their liases. 



WINTER TREATMENT. 



When the trees have become dormant, after the falling of the leaves, 

 they can be trimmed and thoroughly 

 sprayed with a strong kerosene emul- 

 sion, which will kill every scale reached 

 by the spray, without injury to the trees. 

 Scarcely one-fourth the quantity of 

 emulsion is required to spray a tree in 

 winter condition that is necessary when 

 a tree is covered with dense foliage and 

 both sides of the leaves must be reached 

 with the spray. Some excellent results 

 have been obtained by Mr. S. Arthur 

 Johnson * in experiments against this 

 pest in Denver, Colo. He found that 

 kerosene emulsion 25 per cent or more in strength or whale-oil soap at 

 the rate of 1 pound to 1 gallon of water was very effective, apparently 

 killing all scales which received the spray. 



SUMMER TREATMENT. 



Kerosene emulsion of not more than 10 to 12 per cent of oil can be 

 thoroughly applied with safety to maple trees, but the tips and margins 

 of the leaves may be injured even at this strength. Box-elder will be 

 almost defoliated with a 12 to 15 per cent solution. Less than a 10 per 

 cent emulsion will be of little value against the young unless they have 

 recently hatched. Since the hatching period may extend over six or 

 eight weeks, it will be seen that more than one spraying will be neces- 

 sary to insure success, and, coupled with the fact that it is a very diffi- 

 cult and disagreeable task to thoroughly spray a tree in foliage, the 

 winter treatment will be found more satisfactory in every way. And at 

 that season the larvae of predaceous beetles would not be destroyed. 





Fig. 4. — Hyperaspis binotata: a, adult; 6, 

 antenna; r., palpus; '/. larva— enlarged 



(original). 



1905: Bnl. 52, U. S. Dept. Agr., Bureau of Entomology, pp. 85 88. 



