I love using
stump dirt as potting soil, and last year I concluded
that this
miraculous substance was probably mushroom compost. Now I'm going to
guess again --- maybe beetle castings?
Three weeks after Mark cut
down a very
decayed stump, I
started piling the debris in my wheelbarrow to move to a new hugelkultur mound. Imagine my surprise
to find the rotting wood literally wiggling with life!
The most obvious living
things in the stump were these impressive beetles. At least half
a dozen were present, which is typical of the Horned Passalus (Odontotaenius
disjunctus) since
the species is subsocial, with several adults sharing the duties of
childcare.
The Horned Passalus eats
"decaying wood and/or fungi" (according to Bugguide.net), and I realized that the round
pellets that make up stump dirt do look a lot like castings (aka
poop). I wonder if beetle castings have the same near-mythical
properties as worm
castings?
Of course, it's not
really fair to assume the beetles are entirely responsible for creating
stump dirt. The log was also home to wolf spiders, slugs, sow
bugs, wood cockroaches (hiding in galleries in the less decomposed
wood), tiny snails, and much smaller inhabitants that I could barely
make out with the naked eye. So the jury's still out on who or
what produces stump dirt.