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Frequently Asked Questions

Getting started:


There are over 300 species of segmented worms that live all over the world. Eisenia fetida, more commonly known as red wigglers are the best species for eating garbage and living in captivity. Red wigglers are surface feeders, adapted to foraging for food just below the surface and hiding there as they consume double their body weight in food sources daily.


The number of worms you will need in your bin depends on how much garbage your household consumes in a week and how quickly you want your garbage vermicomposted. If you have a large family that eats lots of fruits and vegetables you will need more worms than a single person who eats less compostable matter. We suggest 3-5 lbs. of worms for a large outdoor black bin, 1-2 lbs for an 18 gallon bin and ¾ lb for a smaller under the sink bin.

What do the worms eat?  Is there anything I shouldn’t feed them?

Worms eat garbage. They especially like organic waste such as discarded fruits and vegetables — typical household waste that would normally be sent to the landfill or traditionally composted. But worms will eat lots of other things as well, such as vacuum cleaner bags, discarded natural fiber clothing, and animal fur.

There are those who say: “Don’t feed them citrus.” Or “They don’t like onions or acid food”. We don’t know if anyone has ever REALLY studied these food items. It may take the worms longer to eat these items, but if that is all there is – I would bet they will be right there eating. Just like all of us, they have their favorite foods. We have found they especially like melons. If they have a choice between melons and apples they will choose melons; between apples and orange peels, they will chose apples. The conclusion is that you don’t really need to worry too much about what they want to eat. They will adjust given time. The bigger your bin, the more options they can have. With a small, under the sink bin, it may make sense to be a little more discriminating since they don’t have as much room to move around and pick and choose. Everything is fine in moderation (this includes coffee grounds). They do not like Lunchables – a good thing for those of you teaching nutrition!


Bedding material should be different from the food you feed your worms even though your worms will eat the bedding. Shredded paper, torn up cardboard, peat moss, coir (coconut husks), or any combination of the above are frequent bedding materials. Bedding should be moist but not wet. It is a good idea to mix several bedding materials of different sizes and consistencies so air pockets will form. The worms need an aerobic environment because they absorb air through their skin. If the bin is too wet it becomes anaerobic and will begin to smell.

General info:


Regular composting is thermophilic which means that it depends on heating the material to 135oF and requires bacteria that like high temperatures. Temperatures that high will kill worms. Vermicomposting is mesophilic and doesn’t require high temperatures, but rather works at variable air temperatures and uses different bacteria. The worms speed the decomposition of organic matter, add beneficial organisms to their castings which enhance the soil, and play other more complex roles in the soil food web.

Do worm bins smell?

Worm bins should not smell if they are properly cared for and in balance. If your worm bin smells it has probably become anaerobic because there is not enough air. The lack of air could be caused by not enough holes to allow the air in, or by too much liquid in the bin. If your bin is too wet, anaerobic microorganisms will take over and things will begin to smell.

Should I be stirring my worm bin the way I might a regular compost bin?

No! Let the worms do the work. Worm bins should not be stirred. It is best to leave them alone and let the worms do their work. This is especially important when you have started a new bin. Leave the worms alone and let them adjust to their new home. It will take them some time to get used to their new surroundings and the change in food. Just like these changes would affect us, it is best to give the worms time on their own to get used to their new home. This adjustment should take at least a couple of weeks.


The worms prefer to work when the temperatures are between 60oF and 80oF. They will survive higher and lower temperatures but if the extreme temperatures are prolonged they may become overly stressed. It is important at higher temperatures to make sure the worms do not dry out. If the worms are subjected to freezing temperatures leave them alone. In extreme temperatures, either hot or cold, the worms will migrate to areas that are more comfortable.

What should I do with my worms in the winter?

If you have an inside bin, your worms can continue just where they are.  As the temperature drops their activity may slow down, but unless the temperature drops below freezing, they will be just fine.  Worms in outside bins, depending on how cold the winter gets, should survive with a few considerations. The more insulation they have, the happier they will be. Cover them with any type of insulating material – old blankets, vacuum cleaner bags, sheep’s wool, etc. The worms will gravitate to a safe, worm place or go down into the ground and return in the spring. If they are particularly stressed by the cold, they will reproduce, leaving cocoons behind that will hatch in the spring. Don’t be discouraged if you don’t see any worms early in the spring. Be patient and they will show up when the conditions are right.  You should continue to feed them all winter — even if at reduced levels.

What do baby worms look like?

Baby worms look like tiny pieces of white thread less than an inch long. They gradually turn a light shade of pink and then begin to add weight and look more like the adult worms. It will take them awhile to develop the clitellum that is necessary for reproduction. In a healthy bin you should see worms of all sizes.


My worms are escaping, what should I do?

When you first put worms into fresh bedding, they may initially try to escape.  If you keep the lid on, they will gradually get acclimatized and remain in the bin even when it is uncovered.  Once your vermicomposting is underway, worms attempting to escape is a signal that conditions in the bin are not favorable.  The bedding may be too moist, which you can solve by mixing in some dry bedding. Or, the conditions may have become too acidic.  Another possibility is that the worms are not getting enough to eat.  If all of the food and bedding have decomposed, the remaining castings will not continue to adequately nourish the worms, and it is time to harvest them and begin again with fresh bedding.

If my bin has become anaerobic and smells, what should I do?

If the bin is too wet you must drain the liquid.  Tip the bin and get rid of the extra water. If this is not possible, add some shredded paper, cardboard, or a knee high filled with dry peat moss. Do what you have to do to get rid of the extra liquid. You can also leave the top off for a while. Generally we don’t recommend stirring the bin up – but this is one time when that might help produce some air pockets. The worms breath through their skin so they will not survive in an environment that is so wet or compacted that they can not breathe.

Why do I see dead worms?

In a properly maintained worm bin, worms will continually die and decompose without being noticed, and the population with replenish itself through reproduction. If you notice many dead worms, there is a problem. Either the mixture has become too wet or too dry, too hot or too cold, or available food supplies have become depleted (see “My worms are escaping, what should I do?”).

How can I control the fruit flies?

Although fruit flies do not pose any health hazards, they can be a nuisance. To avoid breeding flies in worm bins, make sure to bury all food scraps in bedding. Monitor the decomposition of food that you add, and hold off on adding more if the scraps are sitting longer than a few days before disappearing. Keep bedding material moist but not too wet, since overly wet conditions encourage the proliferation of fruit flies.

If a fruit fly problem does develop, stop adding food until the worms have had a chance to catch up with the existing supply, and add dry newspaper strips if the bedding appears soggy.  If the outdoor weather is suitable, you might want to air out the bin by leaving it uncovered outside for a few hours.soda bottle

You can build a simple but effective fruit fly trap that can be placed either right in the worm bin or anywhere in the area where the flies congregate. Take a soda bottle and remove the lid.  Cut the bottle in two, with the top part slightly shorter than the bottom part.  Pour cider vinegar into the bottom part to a depth of about half an inch. Then, invert the top of the bottle into the bottom, forming a funnel leading into the bottle.  Fruit flies will be attracted to the vinegar, and they will drown or get trapped.1

1 COMPOSTING IN THE CLASSROOM, Nancy M Trautmann and Marianne E. Krasny, p. 38

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