What is this in my compost bin?

sara_in_phillySeptember 8, 2010

What is this white wiggling thing in my composting bin? They can be as big as 1/3-1/2 inch long. I have seen this in the past, but never in this quantity. At first, I only see them under melon skin, now it seems my compost bin is full of them, it seems half of the bin's content is this, even deep inside the bin.

What kind of lava is this? Are they maggots? But I don't see plume of flies coming out of the bin when I open it. My compost bin is enclosed, with cover and everything.

The volumn of compost in reducing awfully fast, it it because this lava eating it?

What did I do wrong?

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joepyeweed(5b IL)

I would say that you have done nothing wrong. Those maggots will reduced the large bits into smaller bits and then poop them out as bug poo. Bug poo makes good compost.

If you don't want maggots, then you need to actively manage a hot compost pile, by turning more frequently and paying closer attention to the balance between carbon and nitrogen.

i usually just cover them up with a thick layer of browns because I don't like to look at them, but I consider them beneficial to the decomposition process in my cold, passively managed compost pile.

    Bookmark   September 8, 2010 at 11:32AM
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bill13286(7 DFWTX)

Hi..These are Black Soldier Fly larvae. They are usually found in compost that is a little wet. Many people, (myself included) consider them beneficial, as they help break down the compost Other people think that they do not belong in the compost process. Adding more browns and letting the compost dry out some will help to control them. This seems to have been a great year for them. They make very good bait for grandsons to catch lots of fish. Have a great day..

    Bookmark   September 8, 2010 at 11:39AM
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Thank you, joepyeweed & bill13286! I guess I will just cover them up then. They are ugly looking thing. I can't keep my compost pile hot anyway even if I wanted to.

    Bookmark   September 8, 2010 at 12:04PM
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joepyeweed(5b IL)

I've heard it repeated again and again, on this forum, about wet compost attracting BSF. Which is contrary to what I've experienced. My pile is typically on the dry side (I put in lots of dry shredded paper and lots of dry straw for covers) and I still get them. IMO, its not the moisture that attracts them, its the raw fruit and veggie scraps. IME, the buggers do make the pile moist with their bodily excretions. So adding a layer of browns on top, helps balance that out.

    Bookmark   September 8, 2010 at 3:23PM
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I have these same larvae in my compost whenever I add cantaloupe rinds. This in the only time I have them and thought their parent might be attracted to the smell of decaying cantaloupe more than other stuff. What others have said about moisture makes more sense, since cantaloupe have lots more moisture than any other things I put on the pile.

I've never had any problem with odor as you normally do when fly maggots are around, so I never worried about them. I have lots of birds in my yard because I feed them year round. I had noticed that the birds never seemed interested in the larvae, so I thought they might not be regular fly larvae or mealworms. I even put a bunch of them in a pan near a bird feeder, and nothing ate them.

After seeing that BILL13286 identified them "Black Soldier Flies", I search on Google to read more about them. It seems that some people use them for Vermicomposting like earthworms. These guys make red wigglers look downright lazy and finicky.

The link below from the Vermicomposting Forum has lots more info about them. Once I saw a picture of the adults, I recognized them from my yard right away. I had always thought they were a kind of wasp before.

The one problem I've had with them, was that I use compost when I re-potted a large ficus tree last fall. This spring, I had about a dozen of the adults come out of the dirt in the plant's pot. I aways put my ficus tree outside for the summer, so I went ahead and moved it outside when the little guys started hatching. Normally before I use compost in my houseplants, I put it in a bucket and pour boiling water over it to kill bugs, and then let it cool overnight before using it. Last fall I was in a hurry because it was going to frost, and I wanted to re-pot the tree before I brought it inside. I had not sterilized any compost ahead of time and simply got a big bucket full to fill the pot with when I trimmed the tree's roots and re-potted it.

They're sort of cute and didn't bother me, but my wife was creeped out by them when they started hatching. Unlike other flies that bite and transmit diseases, these little guys don't even have a mouth when they grow up. Once they are adults, they have sex and die. Not even a dinner before or cigarette afterwards.

The forum thread below referenced a website that discusses their use for large scale waste disposal. It explains why I had never noticed any smell when I saw them, unlike the smell you notice on things that have maggots. The Black Soldier Fly larvae secrete a digestive enzyme on stuff that helps them digest the material and prevents the "rotting smell" of anaerobic bacteria. Most maggots rely on anaerobic bacteria to pre-digest things for them, which explains why stuff normally stinks when you find them.



Thanks to asking this question. I had noticed the larvae in the summers, and the adults hatching last spring from the potted plant, but I had never connected the two. I'm slow sometimes to make connections that should be obvious.


Here is a link that might be useful: All about Black Soldier Fly

    Bookmark   September 8, 2010 at 5:30PM
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Many people have the idea that maggots, fly larvae, are good in compost. However, these larva need a fairly moist environment to exist and that can mean your compost is too wet to properly get digested by the bacteria that should be doing that. There are numerous fly species and the maggots, the larvae, look very similar so is what you have the Black soldier Fly, the common house fly, the stable fly, or one of the others that ae considered pests?
Some time ago many people stated that having these maggots in your compost was a good thing because they mistakenly thought the Black Soldier Fly and the Black Soldier Beetle were the same thing and they are not.
Maggots in the compost pile may not be desireable.

Here is a link that might be useful: About fly maggots and compost

    Bookmark   September 9, 2010 at 7:02AM
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