“I have been experimenting with a 10 Gal plastic tub to grow worms in my garage. Here is the situation: I have maggots in my tub. Is that a problem? I don’t want the maggots to hatch out as flies in my garage. What did I do wrong? What can I do to correct it? Thanks” ~ Charles
While I wouldn’t say having maggots pop up in your worm bin is a common occurrence, it can happen from time to time – generally only when the bin is sitting outdoors, or at least in a location that is open to the outside environment more than your house. A garage or shed are prime examples, and in fact, I recently opened up a bin I was aging (before adding worms) out in my shed and found lots of adult flies waiting to escape.
Houseflies are usually attracted to wastes that are pretty foul smelling – such as rotting meat – but a stinky worm bin can draw them in too, especially if there is nothing else more appealing in the area. Overfeeding can be a common cause – there is simply too much food in the bin, and the materials not being consumed by worms tend to get pretty foul. If you have lots of absorbent bedding materials (such as shredded newspapers) this can certainly help, but you’ll likely have better success if you simply feed the bin less.
When it comes down to it, having maggots in your worm bin is not a problem as long as you can tolerate it. Like your worms, the maggots are feeding on the rotting food materials, so the only threat they would pose would be as competitors (and a very minor threat at that). For whatever reason, maggots just happen to be one of my least favourite organisms (probably due to watching to many horror films in my younger years – haha), so I tend to frown upon their presence in my vermcomposting systems. Luckily their occurrence has been pretty rare in my experience, so I haven’t had to deal with too many of them.
If you feel your maggot problem requires some sort of solution, I’d suggest removing most of the unprocessed food waste in the bin and as many of the maggots as you can collect as well. If you leave the bin to sit for a couple weeks or so, the worms should help to convert it into a pretty unappealing fly habitat.
I should mention that there ARE other varieties of flies that can invade your bins or in fact hitch a ride with your worms when you buy them. If your supplier feeds their worms with manure, there is a decent chance you may encounter one or more of the various kinds of flies that live and breed in manure. One variety that I seem to encounter quite a bit (much to my chagrine) is a biting fly that looks exactly the same as a harmless housefly.