You say the moisture was good so escape due to drying out or flooding is probably not the cause (and you probably would have found dried up worms around the bin in those cases.

I doubt BSF larva are really the problem since I have had lots of those during some times of the year and they don't seem to directly bother my worms.

Temperature can have a large effect on worms.

Another issue that can sometimes do in a worm bin population, pesticides or chemicals. If you have to "water or mist" your worm bin and have city water, the chlorine can be bad for the worms. To deal with clorinated water you should let it sit in an open container for a few days at least so the chlorine can disapate. Pesticides are bad for worms so it is possible for a banana peal covered in pesticide to do real damage to your poplulation. Any other pesticide sprays that might drift into your worm bin would be bad too.

Thanks for your ideas. The water I use to mist is either tap water left out to dechlorinate in an open bucket for a couple of days or Trader Joe's bottled water. The pesticides are unlikely because we rarely used Round-up and, if so, it's many feet away outside. Your suggestion makes me wonder if non-organic scraps are the culprit. Except that's nothing new around here.

Temperature was almost a problem in the summers of 2005 and 2006. We had a string of 100+ days and they survived that, bless them. We are in Zone 9, so the cold is not an issue.

Since you mentioned that BSF aren't a problem, perhaps I could ask you this: When the BSF moved in, I noticed large, writhing clumps of maggots all over the food, which I generally put into corners at the bottom of the bin, rotating the location each time. It seemed the worms were at the outer edges of the food, so I added more into different corners, fearing there may not have been enough to go around. Still, the maggots were on top of the food and the worms more or less at the margins. It's as though the maggots get there first. And yet, since I know that BSF in worm bins are inevitable, I can't quite accept that this was the problem. When you say that the larvae don't bother the worms, do you mean they all co-exist happily or that basically everyone can get enough to eat? Or, put another way, do worm bins require any different care once the maggot population is well-established? I think I read somewhere that maggot poop is consumed by worms, the better to enhance their castings.

Thanks again.

I've never had BSF in my worm bins, so I wouldn't say they're inevitable.

Deanna

The BSF could have eaten way more than your worms and their action on the surface will make the worms retreat.

What's a BSF and how do you manage to avoid them?

derlenz, Maybe your worm population is going through a regeneration cycle if you did not remove the castings. I read somewhere that if the worms are stressed they will leave the cocoons in the bin/die/and when the new babies hatch they will be more adaptive than the previous generation to the conditions. Did you have some really dry weather down there, for a few days? If so, perhaps the adult worms died and the humidity again came up to make the bed damp and what you have left is worm cocoons that aren't hatched yet? Saltwater could not be too good for them either, if by some chance some ocean water got in there, or dumped out jars where salt was used extensively for pickling food. Are BSF larvae houseflys? Houseflys only eat dead stuff, they don't eat living worms. Maybe your bed got anarobic bacteria and you need to aerate it more often to kill off deadly bacteria. These are just suggestions that pop into my mind as I imagine a bin and no outside predators to account for the disappearance. Thinking, thinking! =o)

You might want to check into your tap water supply. I only reciently learned about another chemical used instead of chlorine for public water supplies. The problem with this other chemical is that it won't disapate just by being left to air the way chlorine will. Aparently it is quite bad for fish so I expect it could be devastating to a worm bin. I've heard it will also kill yeast if you are trying to make bread. I think it requires some filtration (like a britta filter or something) to get rid of it.

I know in my area the local water plant switched from using chlorine in the water to a substance called 'chloramine', which, if I am right, is chlorine bonded with ammonia. Supposedly this stuff could sit in a bucket for a month, and it still wouldn't disappear (or whatever chlorine would do - leave the water). I had tropical fish, and I had to purchase a product that unbonded the chloramine before making the water suitable for the fish.
I do use the tap water to moisten the top of my bin, and have not noticed any large deaths that I could blame it on.

Yea, chloramine is the stuff I was thinking of. A britta or similar filter makes such tap water usable for making bead I hear so it would probably also work to filter the water for worms it that is the issue.