Whut iz da cause?Well that makes sense and explains why I always saw more and lots of compost mites when I was using nematodes
This must be a change in the breeding cycle. Something causes them to go crazy!
Now, what is the stimulus?,
Is it the predatory pressure?
Is it the glut of available nematodes to eat?
If I had to guess its the dead Gnats being more food the mites which makes them multiply but I'm just guessing

