December 17, 2022


The similarities between a colony of worms to a colony of bees continues. 

My worm bin has mites. They look very much like varroa mites, only smaller! About the size of the period at the end of this sentence. Most Internet sources say the mites are harmless, that they're a common co-habitant. My issue with them is I found a pile of them about 5 feet away from the worm bin which, I remind you, is in my kitchen. Had a bag of potting mix not been there for them to congregate under, who knows where I would've found them? I need to get them under control.

Enlarged video of a mite on a egg carton (ideal bedding BTW).
Even more enlarged photo of a mite on a paper towel, head to the left.

Where did they come from in the first place?

From Jim's Worm Farm. Despite negative reviews, and the website stating, "We strive to maintain insect/mite free orders! However,…" I was definitely wishfully thinking when I bought worms from them. So the lesson is, if you're establishing a worm bin, find a friend who has a mite-free vermicomposter who can give you a quart of worms in finished compost. A nuc as it were.

If you click on this photo of my Worm Farm's leach tray, the barely visible dark specks are composting mites.
How to control composting mites?

Mites are actually normal in a worm bin population, but they can become overpopulous. Apparently, too much moisture and mites proliferate. Indeed, I find them in the leach tray, which collects excess moisture (i.e., liquid in your leach tray means you're not managing moisture properly).

Besides adding additional Neem Bliss, here's everything I'm doing and why, in order of what I think will be most effective:

  1. Manage moisture so nothing is in the leach tray.*
  2. Don't feed anything in the cucurbit family, which seems to be the mites' fave. (Big oops on the double dose of butternut squash skin.) 
  3. Reduce pH. Acidity brings mites. Eggshells can provide all the calcium carbonate the soil needs, which helps to lower the soil's pH level and make it more alkaline as opposed to acidic. 
  4. Sprinkle diatomaceous earth over the bedding. DE supposedly is deadly to mites but not harmful to earthworms. However, it only works when it's dry so won't be effective unless I properly manage moisture.
Forget trapping. Sticky traps are minimally effective. Akin to using drones to collect varroa mites, supposedly mellons/squash can be used to collect the composting mites to then be tossed outside. I steamed a butternut and left a pile of guts on a yogurt lid in the upper tray overnight. Very little interest, so mellons/squash being highly attractive is Internet myth.

The bottom tray is where all the action is: worms, mites and gnats feeding on moist bedding and kitchen scraps. I'm using the top tray like a Warré hive quilt. It is filled with dry bedding that is wicking moisture from the colony below. I'm dismayed that there's quite a few mites running around up there.

UPDATE: the mites congregate on the lid, effectively acting as a trap so I could knock down the population by simply cleaning the lid periodically. Managing moisture by setting the working bin askew on the leach tray is a must. No leach, no mites.

What's Neem Bliss?

Besides earthworms and mites, fungus gnats just adore a moist medium of decaying plant matter. They definitely found my worm bin but a couple of doses of Neem Bliss (neem seed meal) appears to be resolving the problem. Neem Bliss successfully eradicated an outright infestation in a bag of Fort Vee compost stored in my garage. The gnats originated in another bag of potting mix on the other side of the garage. If anyone tells you that gnats are weak flyers, then you might also like to know that wolverines make great house pets. Anyway, I simply thoroughly mixed in about a half-cup of the neem seed meal and set the bag outside for three weeks.** Not one gnat to be seen now! I've been using the meal on some houseplants that have been quarantined for months and had way more success with Neem Bliss than anything else I've tried: sticky traps, DE, hydrogen peroxide, soapy water, Root Cleaner and Sacred Soil Tonic. It's been a real battle! Have you ever beaten a fungus gnat problem? How did you do it?

*"The notion that a worm bin should be producing leachate is one of the biggest misconceptions that I feel a need to correct. While all leachate isn’t stinky or hazardous (some may even be beneficial!), it is NOT a desirable by-product of a well-managed worm bin. It indicates too much watering, too much feeding, or not enough bedding added relative to food added."

**The 3-week life cycle of fungus gnats is almost the same as varroa, and understanding it is critical to combatting the pests. See "A look under the cap.pdf".

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Also Good Reading: The Worm Farmer's Handbook by Rhonda Sherman - her explanation for high mite populations are a) too much moisture, b) overfeeding, and c) excessively wet or fleshy feed.


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