predatory mites v. earthworms

philippejardinierJuly 27, 2013

IâÂÂve recently resumed composting, and with no outdoor garden space where I live in Thailand IâÂÂm composting in plastic trash bins on a balcony. Layering well-aged cow manure, veg/fruit kitchen waste, and dry semi-decayed tree leaves, the process has worked well, with breakdown nearly complete in two weeks. The mix, which I turn regularly, is damp but not wet, except when I add a layer of kitchen waste topped with manure.

Hoping to enrich the almost-finished compost, I added a dozen earthworms and watched them burrow and eat, on or near the surface, although I placed some deeper. Within ten minutes they were attacked by what appear to be red mites. The worms convulsed and shriveled, drained of blood, and all died within an hour. The mites are about the size of a pinhead and a semi-glossy red-brown. Whatever their classification, these feed not only on decaying vegetable matter but on live worms.

To see if I could eliminate the mites and re-stock with worms I laid strips of papaya or mango skin on top of the compost. The skins quickly attracted dozens of mites, and I disposed of the lot, repeating the process several times over two weeks. But many mites remain. (A second bin, containing older and more advanced compost, has many fewer mites, but there were still enough to kill all the worms.)

I know that the mites and other invertebrates contribute to breaking down organic matter. But I had looked forward to the results of wormsâ superior aerating and their castings. However, it seems I must choose: Mites or earthworms. I would rather not introduce more worms, only to have them killed by the parasitic mites.

Part of the problem may be that I am composting in plastic bins with no holes in sides or bottom, and at night in the monsoon season I must cover the bins with tight-fitting lids. In this somewhat sealed environment, neither mites nor worms have any place else to go. And despite my regular turning of the mix, perhaps it has remained damp enough to over-balance the mite population.

Should I just let the mites do their job and forget the earthworms? Or should I persist in trapping and clearing out the mites (assuming I could get them all)?

Last question: is there any downside to the mites, such as seeking living plants or humans as hosts? I am new to gardening in the tropics, and have no experience with predatory mites. I would be grateful for suggestions.

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Hmm, this is the first that I heard about mites attacking and "eating" live worms. So far I have known about mites co-habiting a worm bin, sometimes even over-populating it if too much food scraps is present, but the worms will just hide deeper down.
If it were me, I wouldn't use the VC for indoors. If you are determined to have a worm bin, I suggest to start new and not taking stuff from outside especially manure, no matter how well aged, or even tree leaves unless maybe you nuke them for a bit, just for fiber and C. Bottom line, I would only use kitchen scraps and paper product. (Unless you buy your veggie from the Super Market where I suppose it's clean of soil, I wouldn't use unwashed trimmings when bought from the open market/street vendor). With temp. in Thailand, I am sure your scraps will have enough MO in no time to make the worms at home.
Good luck.

    Bookmark   July 27, 2013 at 1:01PM
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It was astonishing to see the mites attach themselves to the worms, and their speed. They stayed fastened on the nightcrawlers, presumably sucking their blood until the worms were literally a loose shell of what they had been. The mites continued to work until the worms had become part of the compost.
IâÂÂm mainly trying to produce my own potting soil because commercial soil mixes at local nurseries are loaded with chemicals, partly from rice hulls. The worms would have been a great benefit. And I like the general idea of their contribution to a small ecology. Years ago when I had outdoor space I had compost piles that pretty much regulated themselves.
You suggest avoiding manure. IâÂÂd thought manure was valuable as a source of nitrogen (in compost with no worms to add castings). Not so? I will try with just kitchen scraps and âÂÂbrownsâÂÂ, paper materials as you suggest and see how it goes.
I also must be careful because of my urban environment. I compost in plastic bins on the balcony and monitor the process closely. Some neighbors in my building likely would be distressed at the idea of balcony composting, however careful I am.
Many thanks for your help.

    Bookmark   July 28, 2013 at 12:40AM
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Worms LOVE manure, It's just with the pred. mite problem you are having, the mites must have come from outside. I was simply doing the elimination process. Hence my comment about where you got your produce/fruit from.
Is it possible to keep your worm bin indoors? A properly maintained worm bin doesn't smell. (Just don't tell your neighbour what's in the box, lol) You still can have your pre-compost bin on your balcony with the tight lid during monsoon season. It will go anaerobic and smell but airing the feed portion before feeding will get rid of most the smell (I hope,lol) Or like many of us, you could store your scraps in the freezer.until needed.

    Bookmark   July 28, 2013 at 1:47AM
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Thanks again. Good tips.

    Bookmark   July 29, 2013 at 12:06AM
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Your composting and vermicomposting abilities need more space. More balconies or gorilla composting which is composting on land you do not actually own. Possibly your kitchen scraps are more than the bins can handle. Are there more outlets to use it? The red mites need a predator to balance their numbers. With both kitchen scraps and manure both being green maybe there is no need for manure unless it is from an animal you are keeping. The red mites in my mind suggest too much green matter and not enough bedding. Living in an urban or even a suburban setting, like I do, with no chickens to feed excess to is sad because it is difficult to put all of our excess resources to their best use. This turns them to waste. Unless bokashi I am unsure about not keeping everything oxygenated. Keeping kitchen scraps with no oxygen turns them to bad things that are hard to then add into a living system. Are there planters in front of your building? Can you visit an area where people rent land to garden? You might enjoy chatting with them. They might want compost.

    Bookmark   July 29, 2013 at 12:56AM
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Those are Bangkok vermi-vampire mites.....very hard to get rid of without physically separating them out of the "bin". I tried those little tiny wooden stakes but......

About the monsoon situation: you might drill some holes in the sides of the "bins" and, for sure, the bottoms.

Also, in every case I've ever seen with unwanted critters like that the problem was mainly overfeeding.

It mine, I would begin separating out the mites a cup of materials at a time. On the other hand, with only those few worms, maybe becoming a vermi-vampire mite composter "mite" be interesting.


    Bookmark   July 29, 2013 at 12:56PM
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