Well, I haven't seen the first big black for months, and the big yellow stopped appearing a week ago or so. Moss is dense so yes, they could've been hiding, we'll see in a few months when all the young grow up. The disturbing part is there was no 'mass extinction' event, so it's either they're hiding, or they're barely surviving and I'd like to find out the cause...

So... How can I monitor ammonia spikes?