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while to ascertain to what extent the beetles of this birch borer feed 

 upon the foliage of birch, willow, and poplar, as it may be possible 

 to reach many in this way by spraying freely with a solution of Paris 

 green, applied at the rate of a pound to 100 or 150 gallons of water. 

 Uninfested trees may be protected by various mixtures, a rather full 

 list of which has been published in Circular No. 24, second series, of 

 this Division, copies of which will be sent to anyone desiring them. 

 In addition to the preventives there described, it may be stated that 

 Mr. Adams is advising a mixture of resin and unboiled linseed oil. 

 This he uses at the rate of 4 pounds of resin to 1 quart of oil, the resin 

 melted and the oil poured in while hot. The resin can be obtained in 

 lots of 4 pounds or more at 2 cents a pound, and the oil in single gallon 

 lots at 40 cents a gallon. It may be applied to the trunk and branches 

 with a paint brush. 



Deudrolene, raupenleim, and similar dark-colored mixtures, although 

 of value against related borers, as, for example, the sinuate pear borer, 

 are hardly to be recommended for birch trees with white bark, as they 

 mar the beauty of the trunks. Light-colored mixtures are preferable, 

 and it is possible that a considerable measure of protection would be 

 afforded by a thick whitewash poisoned with a small quantity of some 

 arsenite, such as arsenate of lead. There is danger in the application 

 of a strong arsenical to young trees, but it will not harm trees of older 

 growth. 



In some instances it might pay, for the protection of valuable trees 

 in private grounds, and for paper birch and trees with similar rough, 

 papery bark, to cover the trunks thoroughly with paper wrappings and 

 whitewash or otherwise treat the branches. 



A mixture of hydraulic cement and skim milk of the consistency of 

 thick paint is worth the experiment against this insect, as it has been 

 found of value against the peach-tree borer. 



The preventives used should be applied to the trees just before the 

 issuance of the beetles, which may be, in some localities at least, as 

 early as the latter days of May. If paper wrappings are used they 

 can be removed as soon as the danger season is passed, which will be 

 within two or three months of the time of first appearance of the 

 beetles. If cement be the remedy employed it should be broken up 

 with a broom or stiff brush as soon as the danger time is over; it is 

 imperative that the cement be not left on the bark of young, growing 

 trees longer than is necessary, as its presence might interfere with the 

 tree's growth. 



A measure of utmost value for the protection of trees from the 

 attacks of borers consists in keeping them in the best possible con- 

 dition, free from fungi, moss, or abnormal growth, from loose bark, 

 and, in short, keeping the trunks as clean as possible. In some cases 

 the use of a fertilizer might assist the trees to withstand borer attack. 



