Wednesday, April 29, 2009


This specimen is a stout beetle of the family Bostrichidae. Bostrichidae has many common names, including "Branch and Twig Borers and Powderpost Beetles," "False Powderpost Beetles," and "Horned Powderpost Beetles." This family contains elongate, somewhat cylindrical beetles with bent-down heads, except for the subfamily Lyctinae. The adults bore into wood to deposit eggs, and the larvae remains in the wood for up to a year before it emerges as an adult. The subfamily Psoinae occurs primarily in the West, and includes the specimen below. They tend to reach lengths of 14-28mm, and are brown or black. Also, the Psoinae family differs from other Bostrichids by having a less bent head and large, strong mandibles.

Coleoptera; Polyphaga; Bostrichoidea; Bostrichidae; Polycaoninae/Psoinae; Polycaon stoutii
Common Name: Black Polycaon

This species occurs mostly on the West Coast, and was probably named after Polycaon of Greek mythology, son of Lelex, king of Laconia, and the Naiad nymph Cleochareia. Polycaon supposedly went, with his wife Messene's aid and encouragement, to conquer a territory and then named it after his wife (Messenia).


  1. Came across this by accident. I live in San Diego and I have a beautiful potato vine which has been growing along a trellis and fence for about 7 years. It seems something is chewing at its woody vines and destroying them - turning the wood completely dry (powdery when I break them off)
    I have noticed the fence has tunnel holes and even the trellis looks like it's been chewed on. Any idea if this could be the culprit?

  2. Unfortunately there are a ton of beetle borers, so you would have to find a larva or an adult for me to try to ID it - either that, or take a picture of the burrows and find a beetle expert - they might know the signs well enough to know the family at least. Sorry for late reply, I just recently turned on email notification for posts, so posts on my older entries were falling under my radar.