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Worm Bin Critter Gallery E-mail
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Written by Administrator   
Sunday, 11 September 2005

by S. Zorba Frankel

The worm bin is an amazing, complex habitat, with hundreds or thousands of decomposer species all working together to turn your kitchen scraps into fertilizer. And you thought you just had a bin of redworms! Not true - redworms are greatly outnumbered by other macro- and microscopic organisms.

All these organisms are decomposers and beneficial to the ecosystem - so don't fear any newcomer you may find in the bin - in all likelihood it's just another one of your redworms' friends.

People new to worm composting sometimes worry that critters will harm houseplants. Remember that these are decomposers that eat dead organic matter, and will not eat living plants. Using your vermicompost in your garden or on houseplants is safe - any critters that come with it will only eat decaying organic matter or simply die off.

Will worms and other critters leave my indoor worm bin and start exploring the house?
Almost never. Your worm bin is the cozy, damp environment, with meals included, that decomposers enjoy.

With that we now introduce you to the most common inhabitants of your worm bin:

Bacteria are the most numerous organisms in the vermicompost system, and the primary decomposers of organic matter on earth. They work on organic material by secreting enzymes which break the bonds holding molecules together, thus simplifying and reducing the molecules to their component elements for absorption. As bacteria simplify the organic matter they make it available to earthworms and other organisms in the system, as well. On the same size scale as bacteria are thousands of other species of microorganisms, feeding on decaying organic matter and each other, forming a complex, microscopic ecosystem called the soil food web.

Molds and fungi

It's not just arthropods and bacteria decomposing the organic material in the worm bin! Molds and fungi are common organisms in a healthy worm system. They feed on decaying organic matter with tiny, hair-like hyphae, secreting enzymes which break down and simplify the organic material. They are also an additional food source to other organisms in the system, including earthworms.

Molds and fungi can also serve as an indicator, telling us if the feeding rate is adequate. Because they grow most prolifically in still, quiet environments, large amounts of mold and fungi indicate there is more food than the system can quickly manage and the feeding rate should be decreased.

Mold and fungi pose no threat to the garden or the animals living in the worm bin, but can cause irritation to humans with mold allergies. If you are allergic to molds, your bin should be kept outdoors or in a garage or basement that is well ventilated to reduce or eliminate irritation.

Mites (Acarina)

Mites are among the most numerous inhabitants in the worm bin, with many different species feeding on decaying organic matter, fungi and other organisms. They are generally found on the surface of the bin, though some predatory species will venture deeper if the material is loose and there is a food source. While beneficial to the system for the most part, it is not uncommon for mite populations to become so large that they stress the worms. Infestation level blooms generally occur on the surface of the bedding and cause the worms to remain in the lower areas of the bin and to decrease their activity. Mite populations can be controlled by removing the upper few inches of bedding during an infestation level bloom, or by placing melon wedges, fleshy side down on the bedding. This is a favorite mite food, and they will soon collect on the melon, which can then be removed from the system. Leaving the bin lid open and exposing the bedding surface to drying and UV light will also control mite populations.

The vast majority of mite species in the bin are beneficial organisms which make up a significant part of the bin ecosystem. Mite species which damage living plants are not found in the worm bin. Control of mite populations should only be considered if the worms are demonstrating stress behaviors like refusal to come to the surface, huddling in a ball, low reproduction or mass exodus. What worms consider to be infestation levels of mites is often very different from the human view.

Mites are cousins to spiders and have large bodies, small heads and eight legs. Their colors range from mottled brown, to red, to glossy white. Species of mite found in the worm bin pose no threat to garden plants or people.

Springtails (Colembola)

There are hundreds of species of springtail, all primarily decomposers of organic matter. They are generally beneficial in the system and have no interest in living plant tissue. It's estimated that more than 80% of the organic matter on earth passes through the gut of a springtail or sow bug on its journey to becoming topsoil.

Springtails in the worm bin are generally small enough to walk on the head of a pin and range in color from brownish to striking white. Being insects, these animals have three distinct body segments, six legs and a pair of short, stubby antennae. Most species have an organ, called a fercula, which is held against the belly. When the springtail needs to move quickly it releases the fercula, which rapidly and suddenly catapults it into the air, hence the common name "springtail". The species most commonly seen in the bin does not possess a fercula, however, and is commonly seen in large numbers on the surface of the bin when there is a quantity of finished material.

Potworms (Enchytraeidae)

Sometimes called white worms, these small, white, threadlike worms are found in worm bins when there is a quantity of finished material. They are beneficial organisms that feed on decaying organic matter and are considered a prized tropical fish food. Some worm growers culture this species of worm for the pet food market. While usually found when the bedding in the bin is slightly acidic, their presence does NOT indicate a pH problem and pH adjustment is not recommended.

Pot worms are white, segmented worms, frequently mistaken for baby redworms. Their bodies are nearly transparent and their digestive system quite visible when viewed through a hand lens. Potworms do not feed on living plants and pose no threat to the garden or people.

Sow or pill bugs (Isopoda)

Also known as woodlice or roly poly bugs, these animals are found in the worm bin, where they shred and consume some of the toughest materials, those high in cellulose and lignins. They may be found through all areas of the bin, except the bottom where there is primarily finished vermicompost, but are most commonly found in the loose surface layers. Sow and pill bugs are considered omnivores, meaning they will feed on both living and dead organic matter. They are sometimes considered garden pests, though they are more commonly found in compost and organic debris piles. In the worm bin they are highly beneficial organisms. Sow bugs have a segmented, armored shell similar in appearance to that of an armadillo, are brown to gray in color, have seven pairs of legs and two antennae.

Fruit flies
Fruit flies are small flying insects with large bulbous, often colorful eyes. They pose no health threat to us or to the worms, and do not harm healthy plants. Still, they are among the least favorite and most common visitors to the worm bin. They seem to enjoy darting out of the bin and toward our faces, startling us as we wonder "Did I just breathe that in?"

Fruit fly eggs are introduced to the worm bin on the peels of bananas and oranges tossed into the bin. The bin environment is an ideal breeding ground, with food and moisture in abundance, and so the flies flourish. Fruit flies are best prevented rather than controlled. Once a fruit fly infestation hits a bin it can take several days to bring under control.

Preventing fruit flies in the bin:
1. Bury food waste under several inches of bedding. Several sheets of damp newspaper or landscape fabric act as a barrier to odors, which will help to prevent attracting fruit flies. It will also reduce their access to the bedding below.

2. Make a fruit fly trap using an attractive liquid, such as: vinegar, wine, soda pop, fruit juice, etc. Put a few ounces of "bait" into a jar or cup and attach a plastic bag on top with a rubber band. Then, cut a few small holes in the plastic bag. The flies go in, but don't come out.

3. Destroy fruit fly eggs or larvae, by freezing, boiling or microwaving fruit and vegetable skins prior to feeding to the worm bin.

Note: Less citrus peels in the worm bin is better. If you've ever squirted yourself in the eye, you know well that their peels contain a substance that can irritate your eye's moist tissues - and your worms' skin. Peels take a couple of weeks for bacteria to decompose them to the point that worms are more interested. For a small worm bin, one orange's peel a day is fine.

Soldier Fly Larvae, or "Maggots"
The maggot commonly seen in a worm bin is grey-brown and about 1/2" long. It is, by far, the least-liked of worm bin critters! It matures into the soldier fly, a large slow-moving fly that lives around compost and lays its eggs there. This fly does not carry disease, and is not a housefly. Though you may have a lot of larvae in the bin, few adult flies hatch, because the maggot needs a cooler, dryer place to go to in order to pupate. The worm bin just isn't that place.

What to do about maggots? Worm composters find that these larvae show up in huge numbers, live a short while, and then disappear. So, be patient. Check to see if you have enough bedding in there. You can reduce the likelihood of having maggots in the bin by mixing in plenty of carbon-rich material every time you feed. The flies are attracted by the smells produced when there's excess nitrogen around.

If you absolutely have to get rid of them, you'll have to empty the bin, rinse off the worms (lay them on some kind of screen), and start your bin over with fresh bedding.

Again, soldier fly maggots are good decomposers, producing a good manure that redworms can further process for you. So, if you can stand their appearance, consider them short-term guests in the worm bin.

Centipedes & millipedes

These long, slow moving, wormlike animals are found in small numbers throughout all layers of the worm bin, where they feed on decaying organic matter.

Millipedes are long and segmented, with two pairs of legs per body segment and two antennae with which they sense their environment. Colors range from black to red, but those species found in the worm bin are commonly brown or reddish-brown. The millipede has an armored shell for protection and coils into a ball, like a pill bug, when threatened.

Centipedes resemble millipedes, but their bodies are more flattened and less rounded at either end. They possess one set of legs on most of their body segments and a large pair of pincers which originate behind the head. The centipede is generally more reddish than the millipede, is very fast moving and is generally found only on the surface of the worm bin.

It's unusual to have many centipedes in a worm bin and one or two are no problem. However, because these arthropods will eat worms as well as other organisms it's a good idea to keep their numbers low. The only way to control centipedes is to remove them by hand which should be done carefully. While not poisonous to humans, they can give a nasty bite with their impressive pincers!

Encouraging Them to Eat More - and Reducing Pest Problems
The food waste you add to a worm bin today, as you know, isn't really touched by worms until at least several days later. How long depends on how quickly a population of microbes can begin to decompose that material, and make it ready for worms to consume.

Now, a great variety of food waste harbors fruit fly eggs, which hatch quickly in the bin! If we could only encourage worms to jump right on that material, before most of the flies are born. Actually, we can do this! Just let food waste develop this microbial population before it goes in the bin. If you collect food waste in a countertop food scrap container, try this: cover the container with a towel (to prevent fruit flies from annoying you) and let it sit indoors for a week. For an even better start, sprinkle finished compost or vermicompost directly onto the food waste as you toss it into the food scrap tub.

Other potential visitors: moles, birds and more.
Obviously, there are a number of predators that must be stopped from gaining access to your worm bin. An outdoor bin without a bottom is an invitation for moles to come and have their fill of redworms! To prevent their entry, fasten 1/8" hardware cloth (a strong metal mesh) to the bottom of the bin. Some large-scale worm growers have lost a significant part of their "herd" to birds. While a small worm bin will certainly keep birds out, watch out for raccoons, dogs and housecats!

Ants occasionally will also visit and even try to set up home in a worm bin. To prevent their access, place each of the bin's feet in a container of water.

Last Updated ( Sunday, 18 September 2005 )
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