White frass and tunnels of oak ambrosia beetle, Monarthrum scutellare, and red boring dust from oak bark beetle, Pseudopityophthorus pubipennis, on coast live oak bark.

Monarthrum scutellare oak ambrosia beetle whitish frass, tunnels and Pseudopityophthorus pubipennis reddish boring dust on coast live oak bark. Marin Co. By Pavel Svihra.  Credit: Pavel Svihra
Credit: Pavel Svihra