Here is a recent e-mail I received from Gordon C.
Dear RWC/Bentley – I just suffered what appears to be a massive worm disappearance, the earthworm equivalent of colony collapse disorder, and I’m wondering if you can give me any ideas on this –
In short, I’ve been tending worms for close to a year and things have generally gone well up until a black soldier fly infestation about a week and half ago. After figuring out that the rotting veggies in the worm bin were the likely source, I put a thin layer of coir on top of the bin, which was at the time fairly chock full of worms. (And put up fly strips for the flies.) I noticed the next day that some of the worms were crawling up the sides of the bin, which is not completely unusual, and I also found a few outside on the floor – definitely more unusual, but not unprecedented and not fatal. A few days later (I had to go out of town just as this was happening), I chopped up some fresh veggie scraps and froze them, which I’ve been told is a good way to kill any fly or other larvae and eggs that may be in them. I then let them sit outside for two days in a sealed plastic bag, in a shady spot. Then, yesterday, I put the fresh scraps in along with shredded newspaper for bedding. A few more were crawling up the sides, and another handful were on the ground outside, and I saw a few worms inside but didn’t thoroughly inspect. Today I did inspect thoroughly, and could only find a tiny handful of worms – like maybe 10. So many hundreds of worms seem to have vanished in the space of a week or so.
Thanks so much for any guidance you can give me on this – it is confusing and concerning me as well as bumming me out!
There are a number of potential red flags in the information you shared with me:
– Black Soldier Fly Larvae
– Leaving town
– Food waste sitting outside, sealed in a plastic bag
Let’s look at each one in more detail…
1) Black Soldier Fly Larvae – while these guys CAN basically co-exist with worm in a vermicomposting system (they don’t attack the worms or anything like that), their presence may indicate that conditions have shifted away from “ideal” for the worms. They tend to appear when temps are pretty warm/hot, and their fast waste-processing can result in even more heat being produced. A good strategy when you start to see these guys is to slow down your feeding a lot and add loads of bedding instead. The larvae definitely prefer a waste-rich environment, so you’ll likely start to see a decline in their numbers after a while.
2) Leaving town – I can’t tell you how many times I’ve heard about worms disappearing when people have gone away for a period of time. The problem is that any number of different things can go wrong during your absence – especially with an outdoor system, and extra-especially (lol) when people add more food than normal so as to compensate for a lack of feeding while they are away. My hunch is that your system IS outdoors (perhaps in a garage or shed?) – since there are BSFLs in it – but I don’t think you are guilty of adding too much food before you went away (it sounded as though you fed them once you got back). But it does seem as though the situation only got worse in your absence.
3) Food waste, sealed in a plastic bag outside – when you are aging food wastes it is definitely a good idea to try to keep them as aerobic as possible. If they get sealed up and are allowed to turn into anaerobic goo they can end up with various compounds that may be harmful to the worms (alcohols etc). I’m glad you at least mixed it with bedding when you added it. Hard to say for sure how much (or even IF) this contributed to the worm decline, but I definitely wouldn’t be surprised if it did.
I think overall this was a combination of factors – likely excess heat combined with declining habitat quality due to the BSFLs and (maybe) the wastes you added.
My suggestion would be to mix in lots of lightly moistened bedding, and stop feeding altogether. If you haven’t been monitoring temps, make sure to start doing so.
Feel free to share a few more details about your set-up and surrounding environment as well. Where exactly is it located? What type of bin is it? What are ambient temps like?
Hope this helps a bit!