Mature beetles emerge from trees beginning in late May and lasting through October with a frequency peaking in July.  Tree infestations can be detected by looking for tell-tail exit holes 3/8 to � inches in diameter (1.5-2 cm) often in the larger branches of the crowns of infested trees.  Sometimes sap can be seen oozing from the exit holes with coarse sawdust or �frass� in evidence on the ground or lower branches.

Above image courtesy US Forest Service

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