A Mite is a Mite is a Mite? Not Quite!

worm bin mites

Apologies for the lapse in posts lately! Lots on the go these days, but still aiming to be much more active in coming weeks and months.

Today I wanted to chat about worm bin mites. Pretty well everyone who sets up their own home system is bound to encounter mites at one time or another. Many people tend to lump them together as a group (ie. “I have mites”) and assume they are ‘bad’ – especially when there is an abundance of them.

Well, mites are of course a ‘group’ – they belong to the class Arachnida (along with spiders) and the subclass Acarina – but they are a hugely diverse group, with thousands of species occupying many different niches and serving a wide array of functions. They are found in abundance both on land and in aquatic habitats.

They are among the smallest of the arthropods (the group that includes crustaceans, insects, mites and spiders – among others), and thus are often over-looked. This also helps to explain why people have difficulty distinguishing different varieties in their bins. According to Walter & Proctor (1999) the highest diversity of mites occurs in soil and decaying organic matter – apparently a handful of forest soil can contain as many as 100 different species (and many thousands of individuals).

Mites can be predators, detritivores, herbivores, and parasites. Some (predator) species are widely used as biological control agents, feeding on a wide array of different plant pests. Generally speaking, most mites found in a compost heap (or worm bin) are relatively harmless, simply feeding on decaying organic matter.

Let’s now chat about some of the varieties you can encounter in your bin. This is purely based on personal observation, and thus not scientifically validated.
My descriptions are based mainly on colour, body shape and speed of locomotion. I’m hoping to study mites a lot more in the future and will hopefully be able to add to this info at some point.

Flattened / Fast moving / Light Brown – These are usually predatory mites. I actually bought some Hypoaspis miles (a predatory biocontrol agent) once in an attempt to deal with a really bad fungus gnat infestation I had in a couple of my bins. They were very small, light brown in colour, and very fast! I’ve seen similar mites in outdoor manure and compost piles, and sometimes in my indoor bins as well. Predatory mites are of course encouraged in a worm composting system since they can feed on other creatures typically thought of as pests.

Reddish-Brown / Slow moving – Mites like the one picture above on the left seem to be fairly common in my worm bins. They seem especially attracted to water-rich cucumber family fruit (or vegetables – however you choose to look at it). The photo above was actually taken on a watermelon rind (during my coffee cup challenge), but I’ve seen lots on squash as well. I’ve actually read that putting some watermelon in your bin is a great way to get rid of them (if you have a major infestation and are worried they are competing with your worms for food). Simply leave the melon to sit for a day or two then remove it (presumably with a huge number of mites attached). For the most part, these mites won’t cause your worms any harm other than potential competition.

White Shiny Round Mites / VERY slow moving – many people report seeing lots of “eggs” in their bins. Most of those who have not yet seen a worm cocoon (which is much larger) assume they are ‘worm eggs’, and I’ll even admit to being fooled into thinking they are the eggs of some other creature. Upon closer examination, you will see that they are in fact mites. This type of mite (which may in fact be a couple different varieties – as the pictures above almost seem to suggest) is sometimes assumed to be a worm predator or parasite since they sometimes found covering worms. The only times I have seen this myself has been when my worms were dying or dead already – the mites seem to be scavengers (like little worm bin vultures – haha). I currently have quite a few of these (or at least a similar variety), but they seem to be attracted to some squash segments I’ve been composting (for an upcoming video).

Those are the main groups of mites I have encountered indoors. In outdoor systems there will definitely be a much greater diversity of species.

One other variety I should mention. There is apparently a ‘red mite’ that is parasitic on adult worms and eggs. Infestations of this mite seem to occur in the beds of worm farmers on occasion. The only (academic literature) records of parasitic mites – on worms that is – I could find were those species that parasitize worm eggs (not adults). Bottom-line, you definitely don’t need to worry TOO much about the parasitic varieties. There haven’t been all that many cases reported from the sounds of things.

Here are some additional thoughts and generalizations about worm bin mites…

They seem to like high moisture conditions and water-rich foods. An population explosion of mites in your system(s) could be an indication of over-feeding, or of your worms dying (which could of course occur if you were over-feeding). Again, for the most part you don’t need to get too stressed out about mites in your bin. Be assured, they are there to serve a function, and may simply indication that your system has shifted out of balance somewhat. In fact, they often appear in abundance early on when systems are not yet balanced.

Ok, thats all for now. Be sure to share any interesting mite experiences you might (or should I say ‘mite’ – yuk yuk) have had as well!

References:
Walter, D. and H. Proctor. 1999. Mites: Ecology, Evolution & Behavior. CABI Publishing, New York. 322pp.

Technorati Tags: mites, worm bins, worm composting, vermicomposting, worm compost, composter, red worms, red wigglers

Written by Bentley on November 13th, 2007 with 34 comments.
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34 comments

Read the comments left by other users below, or:

Colleen
#1. March 23rd, 2008, at 5:23 PM.

We had a massive red mite infestation – where did the red mite come from ? Never had it before and it just appeared when we got some new worms …..

Nancy
#2. April 7th, 2008, at 11:43 PM.

How big are the white mites? My kitchen worm bin has only been going a couple months. Today I found tiny white “pearls” on the sides of the bin that are the size of table salt gains. There were also worm castings all over the sides of the bin. The sides are wet, but the compost doesn’t seem particularly wet. Are the white “pearls” likely to be mites?

This happened one other time a couple weeks ago. I freaked out thinking the white specks were the eggs of some horrible flying pest that would take over my condo. If they could pay the homeowner fees, I’d let them have the condo, but that is another story. That time I set the worm bin outside for two days, and removed what might have been too much pineapple for the worms. No plague or pestilence appeared.

This time I’ve just taken the lid off the bin and covered it with burlap to let it dry. Otherwise, my worms seem happy. There are baby worms, so I would say that worm cocoons look like popcorn kernels when you know for sure you never put popcorn in the bin.

Thanks for your mite ideas.

Bentley
#3. April 8th, 2008, at 2:01 AM.

Hi Nancy,
Your ‘pearls’ do indeed sound like the same white mites that I get. They look like some sort of eggs, and a lot of people have similar thoughts as yourself.
I generally just don’t worry about mites in my bins – they don’t do any harm, and likely do their part to help breakdown wastes.

They seem particularly fond of cucumber family wastes – eg. squash, watermelon, zucchini, pumpkin – I’ve heard of people using these materials to attract the mites then simply removing it (along the attached mites) from the bin.

Kurt
#4. April 8th, 2008, at 12:57 PM.

I too have recently seen an explosion of the little white guys. Table salt size white specks is a good way to describe what they look like. I’ve only had worms for a little over a week now, and I really did add new food to the bin too soon. Plus, in that new food was a handful of cherry tomatoes, which the mites seem to be concentrated on. For the first week I had no worms on the wall of the bins, but I did see a couple in the last two days. Guess that’s a good indication of an out of balance condition. I’l try to leave them alone for a while and let things get settled down….

John
#5. May 9th, 2008, at 3:20 AM.

Ditto the above, I guess it’s pretty common. thanks!

Natasha
#6. December 8th, 2008, at 4:03 PM.

I am also seeing the white mites in my bin and they do not seem to be causing any problems, although I was very worried when I first noticed them. They seem to like tea bags and someone else here mentioned cherry tomatoes. Perhaps they are attracted to acidic things that are added to the bin. Also, I probably have been overfeeding them, but the good news is the worms are still doing very well. I saw plenty of baby worms this morning as well as all sizes in between so it does not appear that the mites are harming the worms at all. I appreciate the posts of others on this topic. Thank you.

Bentley
#7. December 8th, 2008, at 5:08 PM.

Thanks for sharing that, Natasha
In my experience, overfeeding and acidic conditions (often going hand in hand) both seem to cause outbreaks of these mites. Very moist conditions also seem to play a role. I’ve never had issues with them in open systems.
Like yourself, I haven’t had any actual problems resulting from the mites themselves.

Natasha
#8. December 29th, 2008, at 11:00 AM.

What worked for me – I ordered COIR (http://www.gardeners.com/Coir-Worm-Bedding/20708,36-080,default,cp.html) and added about 1/3 of a moistened brick (about 2 inches) of it to the top of my bin. I did not mix it in, just a layer at the top. In less than a week (maybe even 3 days) the mites were gone! The bin also smells like soil again.

Thank you for your comments, Bentley.

Brenda
#9. January 23rd, 2009, at 12:43 AM.

Thanks for the article! I had one small bin that i left alone for 2 months, and it was sludgy (but not smelly) and completely covered in the small brown mites. I knew they were too small to be worm eggs, and then they i realized they were actually moving very slowly. It freaked me out, and i spent all day today wondering if they were a bad omen. You explaination was great.
Btw, I often have the small white “salt” and didn’t know what it was, but it never seemed to do anything bad, so i usually leave them alone and bin conditions eventually balance themselves out.

Bentley
#10. January 23rd, 2009, at 3:17 PM.

Thanks, Brenda – glad the article helped!
A lot of people (understandably) worry when they notice LOTS of other creatures in their bin aside from worms – it is kind of a knee jerk reaction since most of us have basically been trained (via media etc) to assume that lots of ‘bugs’ are a ‘bad’ thing.
It sounds like do definitely have the right perspective!

Jenn
#11. April 14th, 2009, at 8:07 PM.

So I’m curious, are these mites bad for my veggie garden? I mean, if I’m transferring the castings (which have mites) into my veggie garden, are they gonna start feasting on my goodies?

Pam from Canada
#12. June 5th, 2009, at 12:01 AM.

Hi there,

Found your article on mites very interesting. I have been doing tons of research on these little guys lately as my whole vegetable garden is INFESTED with predatory mites. I realize they are good guys but I have been trying to knock down the population to one or two zillion as I seem to come away from my garden CRAWLING with mites and hate my kids to go anywhere near the beds. (They are all over in the grass surrounding the raised beds as well.) I filled my garden beds with city compost that had obviously had these little guys in it. Any idea how I may rid just a few of these mites? I have tried Diatomaceous Earth, and sulpher and they did nothing at all! Please Help?!

Thanks,

Pam from Canada

Cameron Willis
#13. August 19th, 2009, at 6:59 AM.

I’m not certain about the red mites. I’ve found them all over a number of dead, dying or other erratic worms, several of which had cysts or abscesses on them. I realize that this may be a coincidence; perhaps my worms are dying of something else, and the mites are feeding on them. But the close coincidence of red mites appearing and then dying worms suggest these may be something unusual. On the other hand, are you aware of any diseases of worms leading to large cysts and erratic, pained or stunned behaviour? I have a small bin, with no problems for six months, and I’ve even managed to introduce sowbugs as a secondary detrivore group, and they are definitely untouched by any parasites (though I realize that annelids and crustaceans are NOTHING alike). Troubling, all the same.

Bentley
#14. August 19th, 2009, at 1:25 PM.

Hey Cameron,
I have yet to even see a “red” mite in my own bins, so I can’t really comment on your observations (other than to thank you for sharing – very interesting).
I do have some other interesting findings to share however (observed after writing this post). The brownish species of mite that I commonly find in my worm bins, while seemingly harmless to worms, actually DOES seem to be an arthropod parasite. I have found groups of them attached to the back of insects, insect larvae and sow bugs on a number of occasions. I am glad you posted your comment since it has reminded me that I wanted to write a post about this!

Lindsay
#15. October 29th, 2009, at 11:16 AM.

Are there any other ways to get those red mites out of a bin? I work in a school and I’m concerned the parents of my science students will freak! I don’t have access to watermelon until summer…

Bentley
#16. November 3rd, 2009, at 7:58 PM.

Hi Lindsay – unfortunately the only real suggestion I have for you is to leave chunks of watermelon (EDIT: Just read that you don’t have watermelon – whoops) canteloupe, squash, cucumber etc in the bin for a few hours then remove them and wash the mites off. If you do this over and over I would imagine the numbers could be reduced quite drastically. Just be sure not to leave the materials in long enough to actually lead to more mites being produced.

Maybe some camouflage would also help – add LOTS of shredded newspaper etc so they are not as obvious.

Lastly, when it comes down to it education is the key. Assure people that these are COMPOSTING mites that feed on decaying organic matter – they will not live for an extended period outside the bin nor will they cause any harm to the students.

Kate in Sacramento
#17. November 9th, 2009, at 3:38 AM.

I found this article because I have both brown and white mites in my outside box in HUGE numbers. This happened before and I had to physically remove them. I took out all my worms and put them in a plastic bin then used the “light sorting” method to remove the compost/bedding etc. and then I was left with a huge writhing mass of mites. I took a Bar-B-Que scoop out and dumped several scoops of mites into a bucket of water. Life in the bin was good for several months but they are back. I was feeding chopped up pumpkin from several neighbors Halloween decorations and obviously over did it. Challenge is that I have A LOT more worms now and I don’t want to pull them all out again.

Here is my question – Will the mites go away when the bin gets back to normal feeding or will the population stay put and just eat what ever is around? I have been using the cucumber method to get rid of them but only the brown mites are taking the bate.

Bentley
#18. November 9th, 2009, at 4:17 PM.

Hi Kate – interesting that you mentioned adding the pumpkin waste. One of the things I have noticed about mites is that they seem to absolutely LOVE cucumber family waste materials – so melons, squash, pumpkins etc.
I my previous response (above) I mention a way you can remove quite a few mites using pieces of cucumber etc as a trap.

I myself would personally just let everything sit for awhile – maybe just add moistened cardboard for food. Once all the food waste has become nicely processed you should see the mite population decrease.

Lindsay
#19. February 24th, 2010, at 9:57 PM.

HI all!
So the mite advice was great, kept under control, but they were still present… well we used some of the compost in a planting of a potato, and months later, we’ve discovered that the red mites have eaten half of the potato we’re trying to grow! The potato was planted in a separate container from the worm bin, but with compost from the worm bin. Clearly, the mites travelled with the compost. Am I going to have to throw away my compost?! Are the mites going to eat whatever I plant in the compost!? (I’m a first year science teacher at a school and this whole mite problem just keeps rearing it’s ugly head…)

Mention from Calevphoto.com
#20. April 8th, 2010, at 5:22 AM.

The Mighty Mite | CalevPhoto: course, most of us know mites as garden pests or waste bin pests. I doubt this particular one is ...

sally
#21. August 7th, 2010, at 11:38 AM.

Could someone tell me if these red mite are the same red mite that infect chicken pens??

Bentley
#22. August 10th, 2010, at 4:19 PM.

Hi Sally,
There are many thousands of species of mites in the world, occupying all manner of niches – so the chances of worm bin (composting) mites being the same as a chicken pen mite are pretty slim – unless of course you are referring to mites that live in and feed on the chicken litter – there is certainly a much better chance that you would find similar mites in that sort of habitat.

Jorge Cubas
#23. October 12th, 2010, at 8:31 PM.

Hi,

I’m not sure if my question weill get answered as it seems this was posted a while ago, but here goes.

We have a midscale (3X8 ft) worm bin at the AREAC center in Brooklyn College to grow worms as a protein source for fish in an aquaponics system. Lately, we have experienced a boom in the red mite population. At first, I did not worry too much as they seemed to parasatize other pests (beetles, and other grubs), but lately, I have noticed worms with what I can only describe as pockmark-like indentations and dead/dying worms covered with the mites.

Could they be preying on the worms? The temperatures in the bin are usually 26-28 Celsius and we feed approximately 10-15 kg of food waste a week (which is broken down manually and mixed with about 15% paper, 15% water).

Thanks,
Jorge

Bentley
#24. October 13th, 2010, at 1:30 PM.

Hi Jorge,
I’m definitely familiar with the mites you are referring to, but I just haven’t seen any evidence of them preying on or parasitizing the worms (unlike some of the other critters in the bin). It is however quite common for mites to start feeding on the worms while they are dying (they seem to be like the vultures of the worm bin). The “pockmark-like indentations” sound unusual – not really sure what that might be an indication of. I would probably suggest cutting back on the food and potentially the water (does the bin drain? does it tend to dry out?) while upping the bedding materials.
Keep me posted – this is intriguing.
Thanks for popping by

Jorger Cubas
#25. October 13th, 2010, at 3:55 PM.

Thanks for your quick response! Long time reader, 1st time caller btw.

There is no leachate, and I have actually been using the following report from ROU in Australia to better guide me in the feeding methods –
Recycled Organics Unit
. Although, sampling has shown that we have about 15-16 kg of worms in a 2m^2 bin, so I think you’re right, as I’ve been feeding on avg. 14-17 kg of waste per week.

Here at CUNY Brooklyn, we’ve been trying to work with the dining staff to get as varied a feed as possible – it is difficult, however, and the worms have been mostly raised on grits, bread and coffee grounds. I’m guessing my C:N ratios are out of whack b/c of this.

-Jorge

Bonnie Van Meter
#26. March 28th, 2011, at 1:26 PM.

I had a potted oregano plant from the nursery that I put into my chick brooder for a couple of weeks. A couple days ago, I noticed it was getting puny/beat up, so I set it on top of my white cardboard worm box under the light. The next day I was watering my wormbins and noticed HUNDREDS of tiny fast moving red spider mites. Thinking that wet conditions GOT RID OF THEM, I sprayed them all down with water and squished any that reappeared. Looks like I shoulda let the bin dry out. What I watered them with LAST WEEK was the dirty chicken water from the brooders that was full of chicken feed, chicken poop, and wood shavings. So I am thinking that A) that bin had too much water, B) the chicken water was acidic, or C) the plant contaminated the bin? I checked all the chicks and found no mites on THEM, but when I was working with the bin and squishing mites, they got on ME!
I’m going to Reset the box up in a new cardboard box and throw the white one outside. I’ll add DRY torn cardboard to the bottom of the bin to help soak up excess water, a tablespoon or so of ground eggshells available. Then I am going to go buy some melon and see if that will help trap them. I do NOT WANT mites in my basement with the baby chicks on one side of the room and the worm bins on the other! HELP????

Jan Mullen
#27. April 20th, 2011, at 5:03 AM.

Bonnie,
I have had white mite infestations in my bin and solved the problem with the watermelon rind lure (leaving it in the bin 12 hours, rinse off the mites and repeat). Just today I found red mites covering banana disks that I had put in a bin I’m trying to remove worms from, so apparently the red ones love banana. Perhaps that would work for you – rinse the mites off the banana chunk and replace the lure. Maybe the red ones like melon rind too – I haven’t tried that. In my case, I didn’t even know I had mites until I checked the banana disks, thinking I would have baby worms crowded around that I could remove, which I did, but I also had red mites covering the banana. I must say that my bin seems quite healthy, so I don’t think these mites are doing anything bad to the worms. Why are you using a cardboard box for worms? They EAT cardboard – perhaps you should switch to a plastic bin – just drill some holes in the bottom and sides for air flow. Good luck getting rid of the excess mites.

Bonnie Van Meter
#28. April 20th, 2011, at 9:30 PM.

I’m using cardboard boxes for my worm bins, BECAUSE THEY EAT THEM. I set them inside a rubber tote. The cardboard wicks excess moisture and allows more air than just filling up a rubber tote. I don’t like ruining a good tote with holes if I want to repurpose it. I fold the tops down on the cardboard box and it provides darkness for the worms. As the bottom fills up and they’ve eaten the bottom out, I lift the box up a little. It works REALLY WELL. My problem is filling totes up too heavy then not being able to work with them. I solved my mite problem by letting them dry out a bit and the mites all disappeared. Worms are great. Cheers!

aegzandra
#29. June 8th, 2011, at 9:23 PM.

Last night my vermi composter had so many mites (the very fast brown ones) on the lid I didn’t even want to touch it. I did a few things and it seems to be much better.

1. The book that came with my composter suggested this. I soaked a toilet paper roll in milk and left it on top of the mound. When I removed it 24 hours later I also removed a lot of the mites.
2. I tried the cucumber thing suggested above – not sure if this was as effective because I didn’t see many mites on it but removed the cucumber anyways.
3. To catch fruit flies I put some rotting apple in a cup, covered it with plastic wrap and punched a few holes in the top. I was hoping this would catch some mites too but they are so small they went in and out of the holes no problem.

I’m not going to add anymore food for a few days to let the worms work away at what is in there.

There are much fewer mites today then there were yesterday though so thats good news!

Dawn, Bryon
#30. June 21st, 2011, at 3:30 AM.

I just found the worm tea loaded with the white mites? Is it safe to use on my plants now?

Bentley
#31. June 22nd, 2011, at 12:48 AM.

Dawn, Bryon – that’s really interesting. My take on the situation – and really ANY situation involving critters in compost etc – is that these guys are adapted for basically feeding on waste materials. It is very unlikely that compost tea is going to be an ideal breeding ground for plant-attacking invertebrates. I personally think you are totally fine using it (and I would certainly do so).
NOW, that being said (haha) – the fact that you’ve ended up with a huge abundance of these mites has me wondering how you made the tea. Or are you referring to the leachate that drains out from the bottom of a worm bin with drainage?
In that case I would likely aerate the liquid for a couple of days before use.

Steve Murphy
#32. July 8th, 2011, at 12:35 PM.

I have quite a few of the red mites in some of my worm/compost bins and have been worried that if I put any of the castings on my roses that the mites may be the ones that are considered a “pest” to roses? Is that likely to be the case?
I also have a lot of the tiny white springtails in some of my bins and would love to know how to get rid of them, as they seem to be competing with the worms for the food.

jen
#33. July 18th, 2011, at 2:33 PM.

i’ve been “wormsitting” a bin for a few months now. just within the past couple of weeks i am noticing mites are actually leaving the bin and crawling around the vents and on the exterior of the bin. i’ve got lots of worms that seem to be healthy and happy and very reproductive, so i’m not worried about them, but i don’t like the idea of mites making a pilgrimage away from the bin which is in my basement. should i be worried? could i get an infestation in my basement/house? any info would be appreciated.

Mention from Forum.grasscity.com
#34. September 28th, 2011, at 7:43 AM.

Stankie’s Organics – Page 170 – Grasscity.com Forums: save me typing time I agree 100% Here's an article from Bentley at ...

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