. An annotated list of the important North American forest insects. Forest insects. i^c of Chicago, and no doubt thousands of the minute ehalcids were killed, as the}' were found quite plentifull}' 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 should be exercised in the use of spraj', and the bases of trees should be covered with canvas or other suitable material to
. An annotated list of the important North American forest insects. Forest insects. i^c of Chicago, and no doubt thousands of the minute ehalcids were killed, as the}' were found quite plentifull}' 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 should be exercised in the use of spraj', 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 bases. WINTER TREATMENT. When the trees have become dormant, after the falling of the leaves, they can be trimmed and thoroughlj- sprayed with a strong kerosene emul- sion, which will kill ever}' scale reached b}' the spra3% without injury to the trees. Scarcely one-fourth the quantitj'^ of emulsion is required to spray a tree in winter condition that is necessarj'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, apparentl}' killing all scales which received the spra3^ 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 suc
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