Bugs Ate My Worms!

This question comes from Wendy, who is worried that various worm bin creatures are having a negative impact on her worm population.

I started worm composting following your instructions and adding a
pound of worms. Things were going great for a few months. I even
saw some worm eggs and I was able to harvest some castings. Then the
little flies came, little triangle, slow flying things. I haven’t
seen a picture that look like them so I don’t know what they are. I
also noticed little brown seed like things in the bin and then very
little squirmy things. I don’t think they were baby red wigglers,
they moved weird, not like a worm, kind of like a maggot – but much
much smaller. Then the bin started smelling bad and I noticed that
the worms were not moving much. I think the things ate the worms, I
can’t find any, not even dead ones. Help!!!

Hi Wendy!
Ok, so let me get this straight. You have:
“little triangle, slow flying things”, “little brown seed like things”, and “very little squirmy things”?

Sorry – couldn’t resist! All teasing aside, I do know how tough it can be to figure out what all these various bin creatures are.
I’m not 100% sure what your triangular, slow moving flies might be, but whatever they are there is probably a reasonable chance that the little maggots are the juveniles of these flies. The brown seed-like critters are probably a species of mite.

Is it likely that any of these creatures would eat your worms?

Not really…well, assuming this is an indoor bin, anyway. If it is located outside there is a somewhat higher chance of it being invaded by something that can harm the worms.
It definitely sounds as though some (if not all) of your worms have died. I’m not surprised that you can’t find any though – dead worms generally decompose very quickly.

Unfortunately, without seeing the bin for myself or knowing what you’ve been using for food etc, it is tough to know for sure what might have happened. As for what to do now, I would definitely recommend starting up a second bin and moving over as many live worms as you can find. I would also try mixing a lot of fresh bedding into the old bin then letting it sit for awhile, left alone. You mentioned there being cocoons in the bin, so you may be surprised to find that the bin has bounced back with a new worm population in a couple months.

Anyway, sorry I can’t be of greater assistance! Feel free to provide any additional details or ask any other questions you may have.



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  1. I also have noticed strange bugs in my worm composter. I was expecting mites and fruit flies and the like…but I think I have something that is causing trouble. I noticed a cluster of small – half a millimeter in diameter – whitish/yellow things. they mostly appeared on some of the newspaper pieces and leaves. I thought they were worm eggs and didn’t think twice. This was about two weeks ago, my second week of having the worms. I also noticed that every time I opened the top most of the worms would be grouped together on top of the bedding in the corners, lying side by side. Last week they were not on top when I opened it but there were plenty of worms throughout the bedding and in the food. They have been fed a diet of various lettuce’s, tomato’s, bread pieces, coffee grounds and egg shells. I also started the bedding with a small amount of outside dirt. So anyway, this morning I lifted the top and again no worms on top like before, I did see a bunch in the food and what looked to be very small worms – babies. then I noticed many more clusters of the egg shape things. I looked more closely and they were moving. then I looked more closely and they were clustered around a worm and it seemed to me they were eating the worm. The worm was moist not dry and dead, but not moving. So I am worried that they will spread and eat all the baby worms. I got one of the unidentified insects on my finger and inspected it. Mind you this thing is tiny, but it resembled a tick – the round white thing and very small legs and maybe a face. it definitely had legs and crawled. If someone knows what this may be and can confirm that it is either harmful or not that would be much appreciated. I am a month into my worm farm and started with 1500 worms…would hate to have to start over. If you need other info on what I have included in the farm please let me know.

    • Bentley
    • November 9, 2008

    Hi John,
    It sounds like you have a very common variety of worm bin mite. They tend to appear when there is excess food and very moist conditions. Often people assume they are harming the worms when it fact they are simply taking advantage of ideal conditions for their growth/reproduction. They are scavengers and will consume dead and dying worms. They won’t reduce the population of healthy worms however.

    I’d recommend adding a bunch of dry, absorbent bedding to your bin. This should help to improve the situation – absorbing excess moisture and balancing the C:N ratio.

    The good news is that you definitely do not need to start over!

    • mason
    • December 16, 2008

    wew think we have fruit flies,
    what should we do?

    • Bentley
    • December 18, 2008

    Vacuum – apple cider vinegar traps (cup with apple cider and drop of soap, covered with plastic wrap with few small holes punched in) – remove excess food – don’t feed for awhile – lots of dry bedding – leave undisturbed for a number of days – predatory plants – fly paper (dab with apple cider vinegar)

    Hope this helps

    • Dereck
    • March 25, 2009

    To Wendy’s “triangular flying things”: I can almost guarantee that those are fungus gnats. Harmless, but a huge nuisance.

    • Chester
    • April 27, 2010

    I believe I have cluster flies in my worm bin. Lately I have found a fly a day for a week in my house. My bin is indoors and I have only put newspaper and cornmeal in my bin..help …what can I do?

    • Bentley
    • April 27, 2010

    Hi Chester – have you found any larvae in your bin? Dig through the cornmeal and see if there are any there? Generally, worm bins are not great breeding grounds for most fly species (at least not when managed properly).

    • Kate
    • May 2, 2010

    I got two trash-cans of chicken manure a few days ago, fed them to my otherwise impressive red-wormy compost pile and now have what I believe are cluster flies. (They’re larger than house flies, light brown, gross.) If they are cluster flies, they’re earth worm predators. What do I do now? HELP! Thanks.

    • Bentley
    • May 3, 2010

    Hi Kate,
    There are plenty of different fly species that live in manure – most of them harmless to worms, so no need to get too worried just yet. I’d be a wee bit cautious with dumping poultry manure in a worm composting system though – it tends to be high in salts and readily releases ammonia (both are very harmful for worms). If it’s been sitting outside (and getting rained on) for a long time it should be totally fine though.

    UPDATE: Hi again, Kate – just did a bit more reading about Cluster Flies (you got me curious). It seems they are not really associated with manure at all. Apparently adults lay their eggs in soil during the spring and the maggots hatch out and find (soil-based) earthworm hosts. I’m sure they could become parasites of composting worms as well, but I haven’t heard that this is a serious issue. Thanks for mentioning it though. I will continue to research this.

    • Kate
    • May 3, 2010

    Thanks, Bentley. I’ll spread out the piles to lift the salt/ammonia burden. What do you think of capping the whole (spreaded) mess with black, plastic to kill the flies, then let good nematodes go at the larvae after the frost-free date? I’ve been composting since ’94 guess I might have become complacent. Also, we had FEMA-eligible flooding here a month ago and if these guys are cluster flies, I read that they go wherever worms abound. Any and all new intelligence greatly appreciated. Thanks again. K

    • Bentley
    • May 3, 2010

    Hi Kate,
    Your plan should work (although the nematodes might be unnecessary – especially given how expensive they seem to be). As I added in the first comment (as an afterthought), Cluster Flies (according to a university research page) are not associated with manure, compost etc at all, so I really don’t think that’s what these are. Given the lighter color and larger size I think I may actually be familiar with the type of fly you are referring to.
    Again, I’m certainly not saying Cluster Flies are not a potential threat – just not so sure that they would be in poultry manure like that.

    • Beth Black
    • May 10, 2012

    Help! I have flies, not fruit flies but possibly cluster flies, swarming all around the space where I have my worm bin. I think they are cluster flies because there are many,many in the window. I started my Worm Factory 360 in January. I’m now on my second tray and all had been going well until now. About two weeks ago I moved the Factory outside on my shaded porch. That lasted only 5 days because it was too hot for them, even in the shade. We have already hit 95 degree days. I live in El Paso which is the desert and work constantly trying to keep the bin moist enough. Most of the time our Dew Point is 10 or less.
    Do Cluster Flys’ larvae eat my red worms? Most important, how do I get rid of them?

    Thanks for your help,

    • clay Wilcox
    • June 7, 2012

    I think my worms are dead.The soil is very moist and there are lots of slugs and ants but very few worms
    What can I use to add bedding.
    I have lots of saw dust
    would that work?

    • Kristan
    • June 29, 2013

    Hi, I have really tiny little, like almost not visible, species in with red worms. When I take them out they actually jump. I only noticed cause I was fishing and was looking really close. Should I be worried?

    • Marilyn Simpson
    • August 6, 2019

    There are large (1.5″) segmented maggoty things in my worm hotel which are eating both the worms and the compost. What on earth could these be? I’m considering starting over after sterilizing the trays……Please help!

    • Bentley
    • August 9, 2019

    Sounds like Black Soldier Fly larvae – very normal in warmer regions. I would be surprised if they were literally eating live worms though. They are great for processing wastes – they aren’t predators. They tend to thrive in conditions not ideal for worms (hot with lots of rich waste materials). I would stop feeding, and add lots of bedding (eg shredded corrugated cardboard). Ideally, something like a worm hotel should be kept indoors.

    • Luz
    • September 15, 2019

    Woke up this morning to worms desperately escaping my bin I take a closer look and there is hundreds of tiny black Beatles killing my worms. I have no idea where they came from or what they are. I have hundreds of dead worms now.

    • Bentley
    • October 8, 2019

    Hey Luz – there really aren’t too many bugs that will come in and wipe out a worm population. What is far more common is worms dying off for another reason (eg poor bin management) and then some other critter moving in to clean up the dead/dying worms. There are certain kinds of beetles that consume wastes – others that consume the little critters that consume wastes (eg springtails) – so even if these are indeed beetles they MAY not be actually doing anything to your worms. Feel free to email me some photos and/or share more info about your set up (system, where it is sitting, foods added etc)

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