Earthworm Mites

Dealing With Mites in Earthworm Bins

Mites are tiny invertebrates with eight leg-like appendages, naturally found in composted manure and organic material. Mites are especially attracted to moist, acidic environments. They are a common inhabitant of worm bins and beds and vermicomposting systems. Most mites are not harmful to your earthworms but problems commonly occur when mite population increases to high levels.

Types of Mites

There are many species of mites but two common inhabitants of earthworm beds that can become a problem are Brown or White Mites and Red Mites.

Brown or White Mites

Brown or White Mites compete with earthworms for available food, but do not directly prey on earthworms. They feed on decaying or injured earthworms only. However, during infestations they can devour much of the food available in earthworm beds, depriving earthworms of needed nutrients in the process. This increases costs and time spent feeding worms. High levels of mite populations also cause earthworms to stay deep in the bedding and not come to the surface to feed, which results in poor growth and reproduction.

Red Mites

The Red Mite is smaller than Brown or White Mites. Red Mites first appear as white or grey clusters, resembling mold. What appears to be mold, is really clusters of juvenile Red Mites in various stages of development. Red mites are parasites of earthworms. They attach themselves to the earthworm and suck blood or body fluid, resulting in death of the worm. They are also capable of piercing and sucking fluids from egg capsules.

Conditions Leading to Mite Infestations

Since mites are a common inhabitant of earthworm beds and vermicomposting bins, you need not do anything unless there is an infestation. Dramatic increases in mite populations are almost always caused by one of the following:

Too Much Water

Bedding that is too wet creates conditions that are more favorable to mites than to earthworms. Avoid excessively wet beds by improving drainage, and turning bedding frequently.


Too much food can cause buildup of fermented feed and heat up worm beds plus lower the pH of the beds. Slow down feeding schedules, or lessen amounts fed, so that all feed is consumed within a few days. Modify feeding schedules as temperatures change because earthworms consume less food in colder temperatures. Maintain beds around a neutral pH of 7.

Excessively Wet or Fleshy Feed

Vegetables with a high moisture content or pulp from juicing and blending, can cause high mite populations in earthworm beds. Limit the use of such feed if high mite populations are discovered. Discontinue until mite populations are under control.

Ways to Reduce Mite Populations

The most effective methods of cutting mite populations include the following:

Exposure To Sunlight

Uncover the worm beds and expose them to sunlight for several hours to allow bedding to dry a bit. Reduce the amount of water and feed.

Place Newspaper on Top of Bins

Place moistened newspaper on top of bedding, and remove the paper as mites accumulate on them. Repeat until mite populations are reduced to acceptable levels.

Place Pieces of Cantalope on Top of Bedding

Place pieces of watermelon or cantaloupe rind or potato slices on top of the worm beds. Mites are attracted to the sweetness of the rinds or peels and will accumulate on them. The rinds or peels can then be removed and dropped in water or buried.

Water, Do Not Flood, Beds

Heavily water, but do not flood, the worm beds. Mites will move to the surface, and worms will stay below the surface. Use a hand-held propane torch to scorch the top of the bed and kill the mites. This procedure may be repeated several times, at three day intervals, if needed.

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