Compost Critter Conundrum

Back when I started my vermicomposting journey there were a number of sites that mentioned that the system should only contain worms and no other bug. At that time if I noticed springtails or mites, my first reaction was how to get rid of them as quickly as possible! These bugs shouldn’t be here! Fast forward about a year later of many unsuccessful attempts at ridding my systems of these critters, I started to research them a bit to see if they were really harmful. After all, the systems still did a great job of processing wastes even with the critters presence.

My view on these critters has changed over the years and in fact I use them to determine the condition of the system. For example, isopods (or sowbugs) tend to favor drier conditions whereas mites and springtails favor wetter conditions. If I think either of populations is expanding too much I can take an action to remedy it. For the increase in isopods, adding water to moisture helps. For springtails and mites, adding additional dry bedding will help.

Here are some of the common critters found in a system with some terrible alliteration!

Industrious Icky Isopods

These creatures are a land based shrimp…yes they are more crawfish than other insects. Isopods are actually really good composters on their own. They are often found in the same habitats as composting worms. Although in a worm bin setting they often inhabit the drier sections, in the outdoors you can often find them in damper areas such as under rocks. They are completely and utterly harmless to you and the worms! They can be unsightly when running around your systems but other than that I view them as beneficial to the systems. I have noticed that they will begin breaking down larger materials that the worms aren’t ready to feed on. They will often be first to feed on the outer rinds of watermelon and pumpkin and even banana stems. Other common names are sowbugs, pillbugs, roly-polys, and wood lice…which is not something one wants to bring up to non-vermicomposters…”Hey, I got wood lice!” is a sure fire way to have people not talk to you…moving on…

Super Sloppy Springtails

Springtails are often found in the damper sections of a system. They are very small, white bugs that can jump. These creatures feast on decaying material and are overall beneficial to compost systems. I often encounter them on food scraps that the worms cannot break down immediately.

Miserly Morose Mites

OK that might be unfair as the majority of mites are again beneficial to compost systems. However, these buggers tend to move around a lot. I have a rather annoying experience with mites in enclosed plastic tote systems. If you are digging around in the system to check on worms or remains of food scraps, mites have a tendency to hop on board your hand and walk up your arm. It is a most unsettling, tingly, creepy feeling. I tend to go overboard with dry bedding in these systems to avoid that…However, there are tons of different types of mites and not all are the same. Bentley Christie over at Red Worm Composting has a great post about mites.

Pseutupendously Pseupor Pseudoscorpions

OK that was cheating a bit. Pseudoscorpions are really cool looking creatures with obnoxiously large claws for its body. These critters look like really tiny scorpions without a tail. They can eat mites, nematodes, and moth larvae. I have noticed them in the damper areas of systems but due to their size they can be hard to locate.

Mighty Munching Millipedes

Millipedes are fairly common in compost systems. They often look like small worms but they move differently and have a hard outer exoskeleton. They too eat decaying material and can be beneficial to worm systems. They can be considered a pest as they can munch on new seedlings but I have never seen this in my experience.

Annoyingly Aggravating Ants

I am referring to the common sugar ant here and NOT fire ants. Fire ants are an entirely different beast that I’m glad are not in my area. Ants can get into systems but will not make their home in one. Ants need drier conditions than a typical worm habitat. However, food scraps are a source of food for them. The best deterrent is to have a thick layer of bedding on top of the scraps. In fact this thick bedding layer is an excellent deterrent for most worm system pests. Other deterrents include used coffee grounds, adding moisture, and diatomaceous earth or DE. DE for certain insects is similar to us walking on broken glass. I have found that the worms don’t really mind DE and it might be a good source of grit! However, only food grade DE should be used and NOT the pool grade DE as it is harmful to humans.

Gnarly Gnagging Gnats

Fungus gnats are tiny flying insects that are quite annoying. They love to buzz around ones ears and eyes. The good news is that they are pretty easy to get rid of. BTI (Bacillus thuringiensis israelensis) is a bacteria that kills larvae of fungus gnats, mosquitoes, and black flies. Although it doesn’t affect the adult BTI will basically prevent the next generation from living. BTI is completely safe to use in a worm system. I prefer to use the bits instead of the dunks and spread it around the top layer if I notice any gnats.

Pretentious Potworms

Just because it’s a worm doesn’t mean you want them. OK a bit unfair but these small white worms often appear in systems that have too much moisture. In plastic totes they can be found along the walls where the most moisture is gathering. They aren’t really harmful but can be an indicator that the system is on the acidic side. Due to their size it can be difficult to see them in bedding materials or any vermicompost, but they are probably there. Adding some dry bedding will decrease their numbers.

Flippin’ Fruit Flies

No other way to say it but they are awful. These bugs will lay their eggs in banana peels, pineapple, and many other fruits. They have a short life cycle but breed faster than rabbits. It is far easier to use preventive measures to control them. The easiest is to freeze all food scraps before putting them into the system. Freezing will destroy the eggs. Also, whenever feeding add a thick layer of bedding on top. This prevents any fruit flies from getting to the food scraps. Although these flies are pretty harmless you don’t want them inside your house. Here’s a link to a number of videos from Newell Davis at World Composting on Youtube that show his journey with eliminating fruit flies.

Other critters

The above tend to be the most common but others like slugs, snails, earwigs, roaches (ewww), beetles, and spiders may also occupy a system. Plus there are countless other creatures that are too small to see such as bacteria, fungi, nematodes, and protozoa. This link from Cornell Composting has some more data on the bugs. The far majority of these are beneficial to systems and are what the worms actually eat. Outdoor systems have even more to battle with as they may have to contend with moles, groundhogs, feral pigs, rats, mice, and a whole host of others.

The intent of this post is not to scare you off! The majority of these critters are beneficial and pose no threat you or the system. If you take a relaxed approach to them you’ll find that the diversity of organisms is actually good. A worm system should really be thought of as an entire ecosystem of various critters that are trying to maintain a balance. Below is an excellent video from Bentley Christie at Red Worm Composting:

2 thoughts on “Compost Critter Conundrum

  1. Great article but I want to make one correction, sugar ants will and frequently do make their home in worm bins. There are numerous YouTube videos showing how frustrating it can be and five of my own bins had sugar ant nests that I could not defeat no matter what I did and ultimately had to dump out the entire contents Wash the worms and start fresh. There’s a lot of different preventative measures people take to avoid this but it is a quite common problem so it is untrue that they won’t make their nest in a worm bin, they absolutely love to


    1. That’s awful that happened to you five times! I’m not sure what was causing your situation but there are a few ways to keep them away. A fully enclosed system with screens for the air holes or an Urban Worm Bag type system will pretty much keep the ants out. Most of the youtube videos I have seen with ant issues have been “open” systems (no lid or large air vents) or outdoor systems where they can gain access. Like you mentioned prevention is the key. Freeze and chop the food scraps for quicker decomposition, use enclosed systems, cover scraps with ample bedding, and don’t overfeed.
      I am curious about your situation. What type of system were you using and was it indoor or outdoor? What size bin or system were you using?


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