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 ¾ 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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