maggots in the compost

Asked July 21, 2020, 11:25 AM EDT

Yes, I anticipate your telling me that these creatures are beneficial to the composting process. Yes. The thing is, it's my compost tumbler that they're occupying. When it rains, the maggots "swim" to the outer surface and land in the barrel's grip-grooves, which--yuk!--makes giving the tumbler a tumble a bit yukky. I normally open the hatch of the tumbler during the day to facilitate ventilation. At the start of this year's growing season I had placed a screen over the open tumbler to keep flies out. I believe they're the buggers that generate these maggots. Right? Well, by June, the maggots appeared. I suppose much smaller flies got past the screen. These days, I open the hatch and secure it so the wind won't bring it down, hoping that the backyard birds will glimpse the maggot-movement and feed on them. So far I've seen only a single gray catbird take the dive, and a sparrow. The real yuk-experience will be the day the tumbler gets too full and needs emptying into a stage-door compost barrel. Shoveling the maggot-laden compost out is not a task I'd wish on any friend. Maybe on certain national political figures but not any of my friends. In advance, thanx. Matthew-Daniel Stremba


3 Responses

In order for us to suggest ways to rid yourself of this problem, it would help if we can identify the type of fly (at least to family) leaving you with the maggots. Can you please try to take clear, focused pictures of the maggots and attach them to this reply? Including a ruler in the picture will not only give us a sense of scale but can help the camera focus on something when the subject is small. You can attach up to three images per reply, but if you need to share more, you can send more than one reply. A separate picture of the setup itself as a whole may help us trouble-shoot the issue as well.



Thank you, Miri. Only this morning (Thursday, July 23rd) was I able to get some pics of one of the maggots, which (along with others) may have been stimulated by Wednesday night's rain to exit the compost tumbler.

These are the two clearest pics I could manage. They're not just dark, but also ridged horizontally down their backs. Maybe that's called segmented?

Let me know what you think.

Thank you much.
Matthew-Daniel Stremba, Baltimore City

This could be a Black Soldier Fly larva (or any type of Soldier Fly) as they are quite common in compost and, as you suggested, even valued for the speed at which they break down the "green" material. To make the compost less appealing for them, you can use more carbon-rich "brown" material and let the batch dry out a bit more. The only way to eliminate them in the future is to make sure the screen covers are as secure as possible when ventilating the tumbler.

If you want to be rid of them faster, you could empty the bin onto a tarp to let it dry as well as exposing the larvae to birds and other wildlife who will probably devour them fairly quickly once discovered. We realize this is not the preferred approach but it will be the fastest resolution to the current problem. Then, the in-progress compost can go back into the bin or (if it's not too raw) simply be used elsewhere outdoors out-of-the-way to finish breaking down on its own.