Maggots in worm farm

Maggots in Compost: Good or Bad? Here’s What to Do

Updated: Nov 27, 2019 | Categories: Garden

I imagine your story is similar to mine. One year after I had my first vegetable garden I decided I’d start saving nutritious food waste to turn into the garden soil.

So the first thing I did was buy a composter, the kind that you can tumble by turning a big crank or spinning it by the handles.

I also wanted to try one out in the open air, so I formed a composter bin out of chicken wire so it’d get maximum air flow and I could turn it with a pitch fork.

As you can imagine, I eventually discovered maggots in the compost bin (my other one has a screen keeping flying insects out of it’s air window).

My first step when returning the pitch fork to the garage was to flip through my gardening books to see what I could find, and then I got bored of that and sat down at the computer.

Fast forward many years and I’ve just refreshed myself on the topic and am here to share with you everything I learned then and now about having maggots in your composter.

Black Soldier Fly Larvae

“What’s that bug in my compost?” you probably exclaimed. Sometimes you’ll see random larvae, worms, grubs, flies, and mealworms when you turn your compost, but compared to the common maggots you find the rest are relatively rare. What are these maggots?

They’re the larvae of the black soldier fly (BSF), scientifically labeled the hermetia illucens. You can identify them because they have a chubby appearance, fatter than the housefly kind you would expect to find in your outdoor garbage bin.

They’ll begin their life as a white color and become grey, light brown, and dark brown as they age and depending on the waste they’re eating, The black soldier fly adult is a mimic fly that’s really closer to the organ pipe mud dauber wasp.

Black Soldier Fly Larvae (BSFL)

Each female black soldier fly will lay as “few” as 200 and up to 650 eggs at a time, preferably into manure, compost, and other types of decaying matter.

These eggs will hatch within 4 days, resulting in maggots (black soldier fly larvae, or BSFL) that are about 0.04 inches in length. These can grow up to 1 inch in length by around the 20th day before they go into the pupal stage and become adults.

Black Soldier Fly (BSF)

These larvae are so good at composting there’s actually entire industries surrounding BSFL farming, like grub composting, worm farming, and even using them as pet food.

So professionals use them and earthworms and fungi to get this job done, but what about us at home. Are maggots in our compost good or bad?

Well, let’s answer that and then get into why they’re in there in the first place. Then we’ll talk about the ramifications of having them snacking on your compost, and offer some solutions to the possible problem.

Is it Okay to Have Maggots in My Compost?

Yes. It’s okay. You’re not going to eat them and they won’t end up in your vegetables during the next season.

Some would argue that it’s better to have these maggots than not to, because they help ensure that your compost bin gets broken down to a level that will better serve your garden.

Others argue that they’ll eat too many of the nutrients. Both are true and neither are critical to the success of your garden.

The reason both are true is because having some will accelerate the breakdown of the waste you’re collecting. Without a little help from bacteria and our insect friends, it’ll never be ready by the next season.

But too many and you’ll be left with sludge that offers little in the way of nutrition for your garden. Sure, a lot of them will die, which recycles some value back to your soil conditioner, but it won’t work out in your favor. This is why we talk below about finding a balance.

It may also simply gross you out and you don’t want them near anything, even two or three steps removed, from food you’ll be eating later. That’s understandable.

We’ll discuss how to get rid of them further down. But let’s look into why you have so many and how to strike that much needed balance.

Causes of Maggots in Compost

We already mentioned that the BSF prefer to lay their eggs in decomposed organic matter like manure or compost. This is because there’s so many BSFL and they need a lot of food especially because they’re so efficient at breaking it down, so they run out quickly.

They also like a warm environment (out in the sun) that has a high humidity (moist food waste).

Compost that is perhaps too wet

The reason you usually find these and not other types of worms, grubs, and housefly larvae is because the BSF will fight off other insects to protect their nest, and compost is a natural pesticide as it is.

And the reason you find these is usually because you’ve cranked the moistness up in your compost bin.

The main culprit is usually having a lot of green waste and other vegetable matter with high water content. People talk about trying to find a balance between “greens” and “browns,” where browns would include dry vegetables like potatoes, hay, some wood chips, etc.

This is a ratio you have to feel out over time, you can’t actually visually gauge this balance.

Another reason you can end up with too much moisture is you aren’t mixing your compost pile often enough.

You should turn your tumbling composter or mix up your open air compost with a shovel or pitch fork frequently enough to not have extremely moist pockets at the bottom or in the center of your bin.

Of course you don’t want to dry it out completely either, so again there’s the balance you’re seeking to obtain.

How to Get Rid of the Maggots in Compost

Again, some larvae are okay and even preferable, but too many can make things move too fast and oddly enough, too slow, sometimes. Let’s look at ways to reduce the number of maggots or even eliminate them entirely:

  1. Add less greens and more browns
  2. Add some lime to your compost
  3. Don’t let the BSF into your bin

Like we mentioned above, greens refer to moist food waste while browns refer to dry waste and plant material. You can choose to add less greens or if you do add more, make sure you add even more browns while you’re at it.

Browns will distribute the moisture and help make it a little too dry for the BSFL’s taste. Also, you can have a thick layer of browns along the top to disinterest the adult female BSF.

We’re talking dried leaves, dead grass clippings, shredded newspaper, wood chips, hay, and other carbon heavy materials.

Sometimes having less greens is good too, though, because you offer them less food, meaning fewer maggots can survive after hatching (and we’re talking about hundreds per fly that chooses your compost as the perfect place to lay their eggs).

You can add some lime to your compost bin. This will raise the pH levels of the bin and convert ammonium nitrogen into ammonia gas which will be toxic for the little buggers.

The only problem is, this is also bad for the microbes that do the heavy lifting in breaking down your compost. They need more nitrogen than less.

Another issue with adding lime is that your compost will ultimately already be on the alkaline side having a high pH level at the end of the cycle. Adding lime will only make that higher, which can be too high for your garden later.

Some will suggest adding sulfur to make it more acidic later, but avoiding the issue altogether is better.

Finally, you can either purchase a composter that is enclosed and has screens built in for air flow that don’t let the BSF through, or try to wrap your open air bin with mesh screens (I’ve not been successful with this, they still sneak through tiny gaps I can never find).

My dad decided at one point he was going to raise chickens for eggs. This lasted a few years but one year he spread his compost out in the yard and let the chickens peck through it for the maggots, and then shoveled it all back into the bin.

I thought that was pretty clever and it’s something you can consider if you raise wild birds like that. You can do it yourself with rubber gloves if you’re so inclined.

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This is my composter above, one that has never had BSFL in it. I wouldn’t mind a few and have even considered contaminating it a bit from my open air bin, but haven’t done that yet.

It’s pretty big and as long as you turn it so water doesn’t get in (I haven’t had issues but I always leave the doors face down), it’s never too heavy to turn.

Composting Maggots: Frequently Asked Questions

To save the quick scroller some time, we’ve collected the most common questions here for you.

Is it OK to Have Maggots in my Compost?

Yes, to a degree. You don’t want a massive infestation or they’ll take out too many nutrients, but some will help accelerate your composting and make sure it’s ready for the next season. The reason to get rid of them is if there’s too many or you just find it gross.

Are Maggots Bad for Your Garden?

No. If you distribute your compost amongst your garden plot before tilling the soil, you’ll turn in the maggots as well, which provide a nutritious value too. Some may grow into adults and fly off, others may suffocate under the soil. But it’s not harmful to you or your vegetables or plants.

Why Does My Compost Have Flies?

Because you’ve allowed it to become one of the ecosystems the BSFL thrives in. It is too moist while being too warm.

If you turn it more often so there’s not moist pockets, that will help, along with adding less green material (vegetable waste) while adding more brown material (dried leaves, newspaper clippings, etc.).

How Do I Get Rid of The Maggots?

Add more brown material and less greens, meaning more leaves, grass, newspapers and less vegetables. You can turn your compost more often to make sure there’s less moisture inside. You can install mesh screens so the eggs can’t be planted.

And you can add a tiny bit of lime to disrupt the pH levels (but too much and you’ll hurt your garden). You can spread out your compost and allow birds to pick out the maggots and then gather it back together in the bin.

Maggots in Your Composter are Fine!

What we’ve learned is that, in most cases, maggots in your compost is just fine. But it can be good or bad. If you allow a giant infestation then you’ll end up with less nutritious compost, but even then the damage is minimal.

Your garden will still be better off with your less-than-perfect compost than with none whatsoever.

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Editor: Rick Worst

Rick is a home design consultant and enthusiast, who’s life is consumed by all things home and garden. Starting as a hobby, Worst Room has grown into an information and inspiration wheelhouse for professionals and home owners alike. Rick serves as owner and editor for our many content contributors. Learn more about Rick & the Worst Room operation here.

Black Soldier Fly Larvae: Pest or Partner?

As if the potential “ick factor” with worms wasn’t enough, some vermicomposters have moved beyond earthworms to eradicating organic waste with the Black Soldier Fly Larvae, a nice way of saying maggots. I resisted learning more about BSFL because a man in the suburbs has his limits.

Many vermicomposters I speak to, especially those in warmer climates, encounter BSFL in their bins by accident. At some point, the Black Soldier Flies themselves found themselves a nice worm bin, laid their eggs and left, only to die themselves no more than 8 days later.

People post pictures of the larvae on the extremely helpful Facebook groups, wondering what these “pests” are and how to get rid of them. Hell, I’d probably want to get rid of them too.

But it wasn’t until my friends Larry Shier and Quoc-Huy Nguyen Dinh each separately began writing about BSFL with Larry taking a more academic angle by writing a highly enjoyable book about BSFL’s potential for waste mitigation while Quoc has documented his own experience with them, both on his site at The Little Worm Farmer , via his really cool online magazine, and his own how-to e-book aimed at getting people started with BSFL.

The BSFL Life Cycle

BSFL end up spending precious little time in the “fly” stage. The adult Black Soldier Fly didn’t exactly win the Darwinian lottery as it lacks a mouth, believe it or not. Not being able to eat, it spends its last few days breeding and laying eggs before, predictably, starving to death.

Under ideal conditions, these eggs grow into larvae in about 4 days, spend at least two weeks in the larval stage before becoming pupae, then finally adults, where they spend their last few days in increasingly hungry copulation.

Black Soldier Fly Larvae’s Amazing Composting Chops

As it turns out, Black Soldier Fly Larvae are ridiculously effective composters!

For instance, here’s a side-by-side of Quoc’s bin.

A couple things to note here though.

Find the fish in the photo on the right. Gone. As you know, fish in a worm bin is a bad idea.

And the time between these two photos? 8-12 hours.

If you’re still not convinced, check out this video of BSFL destroying a couple fish.

It’s pretty gross, in an awesome sort of way.

BSFL Misconceptions

Newer vermicomposters – and I still consider myself in that category – need to overcome a couple common misconceptions about our vermicomposting bins to fully appreciate BSFL.

  • A vermicomposting bin should include only worms, worm castings, and decomposing organic matter. False.
  • A vermicomposting bin will be an ecologically diverse environment, attracting all sorts of critters.Some of these are actually pests, like mites and centipedes, but you should see various forms of life as a sign of success, not failure.
  • Worms are always the best composters. False.
  • BSFL are 75-100 times more efficient at processing waste than earthworms.If castings for your garden are your objective, stick with composting worms like the Red Wiggler, European Nightcrawler, or Indian Blue. But if eradicating waste is the point, then worms don’t hold a candle to BSFL.

BSFL is a Partner For Sure

Now if your objective is to harness the BSFL and possibly raise them, you’ll need a specialized bin like Quoc shows us here. But if they have found their way into your worm bin, there’s no reason to pull them out.

In fact, I’ve learned their frass (which is another fancy word for poop) makes an excellent food for your worms, so there is some serious recycling going on in a bin with both composting worms and BSFL, so much so that I can imagine you’d struggle to find enough feedstock in a worm bin with a lively BSFL community.

To boot, the BSFL themselves make an excellent source of protein for chickens, fish, and other animals while their oil content makes them a candidate for production of biodiesel if production can reach scale.

Learn More About BSFL

Exactly how to grow and use BSFL effectively is beyond the scope of both this article and my own knowledge. But if you’re interested in how BSFL can process your own household waste (to include meats, which is pretty cool) or even how BSFL can be applied to larger-scale municipal waste mitigation, then I recommend Larry Shier’s book, Black Soldier Fly: Eco-Technology for a Sustainable Future and following Quoc’s progress at The Little Worm Farm and maybe even pickup his own book, A Guide to Composting with Black Soldier Fly Larvae.

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A not uncommon experience with home worm farms is lifting the lid to discover a writhing mass of maggots, usually white in colour with a segmented body. Whilst your initial reaction may be one of horror and disgust it is nowhere near as bad as it looks!! Most likely they are the larvae of the soldier fly and they play a fairly positive role in the composting process in that they eat rotting organic matter in much the same way earthworms do. They just like a much wetter environment than earthworms.

Soldier fly larvae in my worm farmSoldier fly larvae

These larvae are the progeny of a benign insect called the soldier fly which is a common inhabitant of kitchen areas particularly. The scientific name for these interesting insects is Hermetia illucens and they are a common inhabitant of compost heaps, manure piles as well as worm farms. They perform much the same role as tiger and red worms in that they eat dead organic materials and recycle the nutrients from them. They are not generally harmful to humans but their presence in a worm farm is not ideal as the conditions that suit them are not optimal for your worms. They tend to exude acidic substances that are detrimental to earthworms and they prefer very moist conditions.

Soldier fly ready to lay eggs in my worm farm

It is my experience that soldier fly maggots appear when the contents of your worm farm become too wet (often when too many moist kitchen scraps are added in one go) or too acidic, or both. They can also appear in compost heaps if they contain lots of kitchen scraps or other organic waste.To tip the balance back in favour of your earthworms, mix in a coarse fibrous material such as shredded newspaper or lucerne hay with moist materials. Also, a sprinkle of garden lime (or Tumbleweed Worm Farm and Compost Conditioner) will neutralise any build up of organic acids.
There is a whole variety of organisms such as mites, frogs, flies and spiders that will be attracted by the composting process. The challenge is to keep the environment such that your earthworms thrive!

For lots of information on home growing vegies, worm farming and lots more, check out the book

“Grow Your Own”….buy it here>>>>

Where do I get the worms?

Flies, ants and other insects

The hungry bin is designed to prevent pests from entering. However, it is a living ecosystem and some small beneficial insects can exist in the bin quite happily. Sometimes these other insects are eating food the worms don’t like or prefer not to eat. Insects may also be present in food scraps that are introduced to the bin, e.g. fruit fly larvae.

The food in the bin will naturally attract other creatures. Sometimes insects like white fly are attracted to the bin because the food is too acidic. Try balancing the food with a little lime, shredded paper, dead leaves or sawdust. Covering the food with a hessian sack, old carpet or damp newspaper will also discourage unwelcome visitors.


If the farm is too dry, ants can also establish their nests in the hungry bin itself. Keeping the surface moist will help discourage ants. Ants can be discouraged from enetering the bin by ensuring the bin is not touching a surface the ants can enter the bin from, and then smearing a layer of petroleum jelly on the legs just under the sockets on the lower body.

Fruit flies

Fruit flies are attracted to rotting fruit or sweet smelling scraps in the bin. Fruit flies will normally be present in the bin, but if you have large numbers it can be unpleasant and indicate that the balance in the hungry bin has changed.

Try burying your food scraps under the top layer. In addition, you can place a couple of layers of damp newspaper flat over the surface. Each of these helps to keep adult fruit flies from accessing the buried food, where they lay their eggs.


Maggots are the larvae of flies. There are many different kinds. The type you may see in your bin will depend on what you are feeding your worms, where you live and the time of year. While many people find maggots unpleasant, they will not harm you or your worms. In fact, they are good decomposers and, like the compost worms, will produce a high-quality casting.

If you haven’t added animal proteins, and don’t have any foul odours in the bin, then it is likely the maggots you are seeing will be black soldier fly larvae. Once your bin has black soldier flies present, it can be difficult to get rid of them. It may be best to simply allow them to grow out of the larval stage (which they do quickly) and fly off. If you have large numbers present, harvest the worms and get rid of all your affected castings (put them in an outdoor compost pile, or bury them in the garden). Then put your worms back into fresh bedding.


Also known as pill bugs, sow bugs and woodlice. They are beneficial bugs in your bin helping to break down all the compostable material. If you wish to remove them, you could lay damp newspaper on top of the food scraps overnight, in the morning remove the paper with the slaters attached. If you have chickens, you could feed them the slaters. Slaters can also be an indication that the bin is dry so add some water to reduce their population.

Red spider mites

Red spider mites are very common in worm bins. They are usually present when there is a source of bread and protein. These mites can be a problem if you find your worm population depleting. You can remove them by putting in food overnight that the mites are attracted to (like watermelon rind) then remove the next morning with the mites attached and wash them off. Repeat the process until you are satisfied with the result.

Black soldier fly

See Maggots above.


Also known as pincher bugs, these are harmless creatures in the worm bin. They generally indicate a slightly acidic environment, which can be remedied easily by adding a handful of garden lime.

White worms

Also known as pot worms or grindle worms. They will not harm your worms but can be an indication that the bedding is too acidic. Add a handful of dolomite lime or garden lime.


These little arthropods feed on composting material but are also known to feed on small insects including the odd worm. Best to evict these visitors as you see them. Watch out for their pincers!


These omnivores are attracted to food scraps. Avoid putting in any meat products. They also like dark tight crevices so you could uncover the bin for periods of time, which will make the worms work at lower levels and discourage the cockroaches from taking up residence. However, keeping the lid on in the first place will prevent them entering. To get rid of cockroaches without using baits you could try a 1:1 mixture of baking soda and sugar. Spread it around the outside of the bin.

Bugs! Creepy Crawlies! What’s in my Worm Bin?

In addition to the millions of micro-organisms working to help your worms digest and compost your waste, there are larger organisms that will appear in your worm bin. Here is a guide to critters you might find, their relationship to your worms, and whether or not (and how) to get rid of them.


Potworms are common in worm bins and enjoy slightly acidic conditions.

Potworms are small white worms commonly found in soil. They can develop into massive populations, especially in compost piles or in earthworm farms. They’re scientifically known as enchytraeids (enn-kee-TRAY-ids) and are segmented relatives of the earthworm. They are often thought to be baby red wigglers, but baby red wigglers are reddish even when they are tiny.

The name “potworms” comes from the fact they inhabit the soil in pots and containers. There is some unnecessary worry that overpopulation will choke out the worm population. That is typically not the case as potworms and a host of other creatures, including those that cannot be seen except under a magnifying glass or microscope, reside peaceably with earthworms, often in great numbers.

When a potworm invasion occurs, they can number as many as 250,000 in a ten-square-foot area. Adults measure about a quarter of an inch, and can literally appear to be in the millions in comparison to your red wiggler worm population. Potworms tend to congregate together under food.

Potworms feed on the same type of litter as earthworms and inhabit rich organic environments such as a compost heap or worm composter. They are efficient at aerating soil and breaking down just about any organic material. This species prefers an acid environment that is moist. Commonly they will spring up (seemingly out of nowhere) when lots of acidic materials are added to the bin, or when starchy materials are added and allowed to ferment. If the bin is too dry, they will die.

The easiest way to reduce potworm populations is with bread soaked in milk. They will flock to a piece of soaked bread and can be lifted out and destroyed in large batches

Just as potworms won’t harm other living worm species, they do no damage to living plants. The only possible problem that could occur with potworms in a worm bin is if their population grows so large that they compete for food with the red wiggler composting worms. However, this rarely happens and potworms generally help with the composting process.

Earwigs can be identified by their pincers on the back of their abdomens.

Earwigs are outdoor insects usually found under mulch, logs or dead leaves. They both need and are very attracted to moisture. Earwigs are rapid runners, and are easily identified by the prominent pincers on the end of the abdomen. The common earwig is a light, reddish brown flattened insect, up to one inch in length. Most species of earwigs are scavengers that feed on dead insects and decaying plant material. Some species are predators. Earwigs may try to pinch if handled carelessly, but are harmless to people. They are not harmful in a worm composter but may eat some of the earthworm food.


The rove beetle is the most common beetle in worm bins.

The most common beetles in compost are the rove beetle, ground beetle and feather-winged beetle. Feather-winged beetles feed on fungal spores, while the larger rove and ground beetles prey on insects, worms, snails, slugs and other small animals. Rove beetles are the most common group of beetles found in composting bins. They are slender, elongated beetles with wing covers (elytra) that are much shorter than the abdomen; over half of the top surface of the abdomen is exposed. Their tail often bends upwards and they can be mistaken for earwigs. Most rove beetles are black or brown. Most rove beetles are medium sized beetles; a few species are up to one inch long. Rove beetles are active fliers or runners. When they run they often raise the tip of the abdomen. Rove beetles don’t sting, but can give a painful bite. They are found in or near decaying organic matter and feed on other insects such as fly maggots.

Beetles are not harmful in the worm composter.


The springtail is usually white and enjoy wet bedding conditions.

Springtails are tiny, wingless insects, usually white in color but may also be yellow, gray, red, orange, metallic green and lavender. They feed on mold, fungi, bacteria and decomposing plant material so they are harmless to earthworms. Springtails can “jump” about 75 mm. They have a tiny spring-like structure under their bellies that causes them to jump when disturbed. Springtails are most numerous in wetter bedding, while numbers decrease as the bedding dries out.

Although they have on occasion been observed to eat dead or weak worms, springtails are primarily a nuisance because they eat the worm’s food and can, when the populations are big enough, drive the worms deep into the beds and keep them from coming to the surface to feed. One deals with them the same way one deals with mites. (See below)


Mites are usually red or brown and enjoy wet bin conditions.

Mites are the most common pests to show up in your vermicomposter. Most worm beds usually contain several species of mites. Earthworm mites are small and are usually brown, reddish or somewhere in-between. They tend to concentrate near the edges and surfaces of the worm beds and around clusters of feed. They are not known for attacking the earthworms but do eat the worm’s food. When the mite population is too high the worms will burrow deep into the beds and not come to the surface to feed, which hampers worm reproduction and growth.

Mites can compete with the worms for available food if the population spirals too high. High mite populations usually result from:

  • Feeding the earthworms overly moist garbage and vegetable refuse as feed.
  • Over-watering. Keep the beds damp but not wet.
  • Poor bed drainage. Ensure that there are adequate drainage holes at the bottom of your worm bin or housing.
  • Remember, the same conditions that ensure high worm production will be less favorable to mites. If you find your worm farm overrun by mites, expose the beds to the sun for a few hours. Cut back on water and feed and then, every 1 to 3 days, add calcium carbonate. Add additional shredded paper or coconut coir to absorb any excess moisture. Drain off any liquid that has collected in the base and check to make sure the spigot is not plugged.

    Fruit Flies

    The worm bin is the perfect fruit fly and fungus gnat haven because of the abundance of organic matter and the moist conditions. Fruit flies are not actually flies because they have multiple wings. Fruit fly invasions are a fact of life in the worm composting world, and they can be unpleasant guests, but they are NOT harmful to your worms or in the composting process. They are simply a nuisance. Fruit flies can be a problem year round but are especially prevalent in the summer and fall because they are attracted to ripened or fermented fruits and vegetables. Fruit flies reproduce quickly and abundantly – each adult can lay 500 eggs in their lifecycle, which is about a week long. The eggs attach to the surfaces of fruits and vegetables, and that is how they travel into our homes. Please see Fruit Flies: Prevention and Control in a Worm Bin for tips and tricks on ridding your worm composter of these nuisances.


    A centipede has one set of legs per body segment and a slightly flattened body.

    Centipedes resemble millipedes, but their bodies are more flattened and less rounded at either end. Centipedes have one set of legs per segment on the bodies and a pair of pincers which originate behind the head. The centipede is generally more reddish than the millipede.

    Centipedes are fast moving predators that will kill worms and should be removed. The stingers behind their head possess poison glands that they use to paralyze small earthworms, insect larvae and small insects and spiders. The only way to control centipedes is to remove them by hand which should be done carefully. They will use the pincers to sting.


    A millipede has a round body and has two pairs of legs per body segment.

    Millipedes have wormlike segmented bodies with each segment having two pairs of walking legs. Colors range from black to red, but those species found in the worm bin are commonly brown or reddish-brown. Millipedes are vegetarians that break down plant material by eating decaying plant vegetation. They will roll up in a ball when in danger. They are harmless to earthworms. Millipedes move much more slowly than Centipedes and have a rounder body.

    Sow Bugs & Pill Bugs

    Sow bugs eat some very tough materials and can help your worms with hard-to-consume items.

    Sow Bugs, also known as a “wood louse” are fat bodied crustaceans with delicate plate like gills along the lower surface of their abdomens which must be kept moist and a segmented, armored shell similar in appearance to an armadillo. They are brown to gray in color and have seven pairs of legs and two antennae. They move slowly, grazing on decaying vegetation. They shred and consume some of the toughest materials, those high in cellulose and lignins. Sow bugs are usually found in the upper areas of the worm composter where there is an abundance of unprocessed organic matter. They are highly beneficial in the worm composter but can harm young plants.

    Pill bugs, or “roly polly bugs” look similar to sow bugs but roll up in a ball when disturbed.

    Slugs & Snails

    Slug eggs can be transferred in finished compost and after hatching, the young slugs can destroy young plants. It is best to remove slugs from your bin.

    Slugs and snails can be found in your vermicomposter. While they will not harm the worms they will eat any fresh kitchen waste in the composter. The biggest detriment is the eggs they lay. The eggs can be transferred into your plantings in the compost providing them with a meal of succulent young plants.

    It is best to remove any slugs or snails you find immediately. If they become a problem you can make a slug trap as follows:

    Cut several 1 inch opening in the sides of a clean, covered plastic container. Sink the container into the bedding of the top tray of the worm composter so that the holes are just above the level of the compost. Remove the lid and pour in ½ inch of beer or a yeast mixture of 2 tablespoons flour, ½ teaspoon baker’s yeast, 1 teaspoon sugar, 2 cups warm water. The slugs will be attracted to the beer or yeast mixture, fall in and drown. Check the container regularly.

    Ants are attracted to a dry bin, so sprinkle water on your bedding or add moist materials to discourage ants.

    Ants are attracted to the food in a worm bin. They feed on fungi, seeds, sweets, scraps, other insects and sometimes other ants. Try not to spill anything near your bins and clear away any spillage as soon as it is spotted. The presence of ants is an indication of dry bedding. Moisten the bedding and turn it with a trowel to disrupt their colonies and most ants will find some place else to live.

    One way to keep ants out of your worm composter is to put each of your bin’s legs in a dish of water that has had a drop of dish soap placed in it to reduce the surface tension of the water. This prevents the ants from walking across the water. Alternatively, most of the garden centers sell ant goo, a sticky substance that is painted around the stems of rose bushes to trap ants. It is eco friendly as it doesn’t contain any insecticide poisons.

    If all else fails and the ant invasion has already become serious, you can dust the area around your beds with pyrethrum dust or douse the ant nest and the trails leading to your bin with a granular insecticide, or use commercially available ant traps, which contain slow release poisons that the ants take with them back into their nests. Please be sure not to use any insecticide on the actual worm bed soil or you will kill your worms. If ants are already established inside the beds soak the section they are in with water and they will usually go away.
    If you don’t want to go to that much trouble, take heart! The ants don’t bother the worms and they actually benefit the composting process by bringing fungi and other organisms into their nests. The work of ants can make worm compost richer in phosphorus and potassium by moving minerals from one place to another.

    Blow Flies & House Flies

    The presence of house flies in your bin can indicate improper food that has been added.

    Excess flies buzzing around your worm bins or worm farms are usually the result of having used meat, greasy food waste, or pet feces as feed. They spread disease and make life miserable for the worm farmer and his family. They can also result in maggots if the beds aren’t properly sealed. If your farm is kept indoors or under some sort of shading – as it should be – then you can hang up some fly strips, which will draw them away from the farms. Again, a properly maintained worm farm will normally not stink and therefore not attract flies.

    Soldier Flies

    Soldier fly larvae and adults are not harmful to your worm bin.

    Soldier flies are true flies that resemble wasps in their appearance and behavior. Adult flies vary in color from black, metallic blue, green or purple, to brightly colored black and yellow patterns. The larvae of the fly are a type of small maggot that feeds exclusively on putrescent material. They are often found in worm composters but are not a real threat to the worms. They do not attack them or compete with them for food and may in fact complement the compost worms activities. Like the vermiculture worms their feces make excellent compost. They can best be kept out of the worm composter by not using meat and fatty waste and by keeping the moisture on the dry side. Make sure that there is a good cover of bedding material over the feeding area.

    These remarkable creatures, unlike the common housefly, do not spread bacteria or disease. In fact, the larvae ingest potentially pathogenic material and disease-causing organisms and thus render them harmless. Moreover black soldier flies exude an odor which positively discourages houseflies and certain other flying pests. When the larvae reach maturity they leave the feeding area to pupate. The adult fly is nocturnal and characterized by very fast and rather clumsy flight. It has no mouth and cannot bite or sting.

    Soldier fly larvae are harmless to you, your worms and your plants. They are very good decomposers and, if allowed to stay in your vermicomposting system, will help to recycle your waste. Just be sure that your worms get plenty to eat as well. The soldier fly manure does make good worm feed as well.

    Maggots or Larvae

    Maggots are good composters and will not harm your worm bin.

    The most common type of maggots found in a worm bin are grey-brown and about 1/2″ long. These are the larvae of the soldier fly, a large pretty, blue/black fly. These larvae are attracted to compost piles and to the worm bin, and will not harm you or your worms. In fact, they are good decomposers and, like the redworms, will produce a high quality casting.

    If you haven’t added animal proteins, and don’t have any foul odors in the bin, then in all likelihood the maggots you are seeing will be soldier flies. Once your bin has soldier flies, it can be difficult to say goodbye to them. Your best tactic is to simply allow them to grow out of the larval stage (which they do quickly) and fly off. If you really can’t stand them, you’ll have to harvest the worms and get rid of all your vermicompost material (put it in an outdoor compost pile, or bury it in the garden). Then put your worms back into fresh bedding.

    Flat Worms & Land Planarians

    Land planarians should be removed from your worm bin immediately.

    Land Planarians, also called Flatworms, are iridescent slimy worms with a hammer or disk shaped head. They eat slugs, each other, and are voracious predators of earthworms. Much like slugs, they hide in dark, cool, moist areas during the day and require high humidity to survive. They are rare in rural sites. Feeding and movement occur at night.

    Land Planarians are extremely destructive to earthworm populations and need to be removed and destroyed upon sight. They can survive desiccation only if water loss does not exceed 45 percent of their body weight. They are thought to primarily be distributed by tropical plants. Planarians are a predator that you will want to remove and destroy every time you see one. Spray with orange oil or bleach, or collect to dry out in hot sun.

    Maggots In A Worm Composting Operation

    “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

    Hi 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.

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    You are likely to find many organisms other than worms in your worm bin! Like backyard composting, you will see a diverse, interdependent community of large and small organisms. They serve as food for each other, clean up each others’ waste, convert materials to forms that other organisms can utilize, and control each others’ populations. For us to arbitrarily decide who should live and who should die in this complex system is difficult, given that one could spend a lifetime studying the various creatures in a worm bin, trying to determine who eats whom and under what conditions.

    So what are those tiny white things in my worm bin? Known commonly as white worms or pot worms, enchytraeids are small (one-fourth to one inch long), white, segmented worms. These creatures are often mistaken for newly hatched redworms because of their size. However, young redworms are a reddish color because of their red blood. Although related to the larger earthworms, enchytraeids do not have hemoglobin-based blood and remain white throughout their lifetime.

    Some worm growers also incorrectly identify enchytraeids as “nematodes” which tend to be present in large quantities in worms bins. However you would not likely see nematodes without a microscope. Nematodes eat decomposing plant material, but they digest only part of it; they like to share! Some commercial growers express concern that these white worms will out-compete the red worms for food and diminish their numbers. However, if your purpose in vermicomposting is to get rid of food waste then the presence of an organism that helps do the job is an asset, not a detriment. These little guys are fine!

    In your worm bin, you may also see hundreds of tiny (1/16 of an inch) white creatures that “spring” away in all directions if you try to touch them. Springtails are primitive wingless insects with a pointed prong extending forward underneath their abdomen from the rear. By quickly extending this prong, their bodies “spring” forward. Springtails are not only numerous but they are diverse with over 1200 species. They feed on decaying matter and fungi, so they are also a helpful member of your bin community.

    Most people shudder when they see white maggots in their worm bin or compost pile. These maggots are the larvae of “compost-dwelling” soldier flies. But don’t be grossed out! In fact, these larvae play a role in breaking down and recycling nutrients back into the soil. Soldier fly larvae are voracious consumers of nitrogen-rich decaying materials, such as kitchen food scraps and manures. Females lay eggs on the surface of the nitrogen-rich material for newly hatched young to feed. So if you want to avoid having these flies and their maggots in your compost pile, make sure you have enough shredded paper and organic “brown” material in the bin to cover the nitrogen sources. In a worm bin, you should bury food scraps down at least six inches down and not worry about competition between the flies and the worms; flies aren’t predators of the worms or their eggs.

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