Common House Borer, prefers softwood/sap timbers, makes round exit holes from 2mm diameter. The frass from the borings is a densely packed fine powder. Beetles emerge from wood generally between November and February.

Two Tooth Long Horn Borer makes large oval holes measuring 3-4mm across. They attack sap or heart timbers. Beetles emerge during the Autumn. Frass is also fine and packed into their exit holes.

The site is also great http://www.anticimex.com/en-NZ/nz/residential/pest-control/borer/