Last July, I heard though the grapevine that Stratiolaelaps scimitus, a predatory mite formally known as Hypoaspis, were available locally. These little darlings eat mites, potentially varroa mites.
(A side note: links to photograph sources are in text under the image. WordPress is having issues with my 7 year old computer, and not all link options are available.)
STRATIOLAELAPS SCIMITUS – predatory mites
Stratiolaelaps scimitus eat lots of other insects. Technically they are termed a” non-specific predator”, gobbling down 1-5 other bugs every day. In the US nursery trade, they are used to kill thrips. Interestingly they have also been used to control mites on tarantulas, snakes, and hermit crabs. In the US, Canada, and the UK (and possibly other areas) some beekeepers are using repeated applications of these mites to control varroa. Here’s some UK links.
The Bee Vet (U.K.) : home page
The Bee Vet (U.K) : Predatory Mite PDF : Predatory Mite PDF from The Bee Vet, UKClare Densley (Beekeeper Buckfast Abby who uses these mites): homepage
Clare Densley : blog post about predatory mites:
There is a downside for their use in beekeeping: Stratiolaelaps scimitus, once placed in a hive, do not stay in the hive. They are ground dwellers. Conceptually, they eat and kill their way though the varroa, while heading for the ground where they will burrow in and reproduce.
MY MITES (the “good guys”) and HOW I TESTED FOR VARROA
My mites were raised in British Columbia, Canada, by Applied Bio-Nomics Ltd. and distributed by a Bellingham Horticulture company, Sound Horticulture . The 25,000 that I got arrived mingled with vermiculite in a one-liter canister. These predatory mites are tiny, smaller than 1 mm in length, which is about 1/25th of an inch.
Tube of Mites that Might eat Mites
There are mites in there
When I received the predatory mites, I was participating in the beeinformed.org bee health survey, which I mentioned in the last post. So every month I had the luxury of having bees from selected hives tested for both varroa and nosema loads. Seemed like a perfect time to test Stratiolaelaps scimitus mites against varroa in my hives.
Marker Designating A Bee Health Survey Hive
TEST OVERVIEW
I was not impressed by the mites work. The results were all over the place.
Treated hives: varroa number went:
- Down in one hive
- Up in two hives
- Down then up in the fourth hive
Control hives (no Stratiolaelaps scimitus applied): varroa numbers went:
- Up in three hives
- Down, then up in the fourth hive
I’ll get to the test results in a moment.
First I would stress that all the hives already had varroa present.
Other beekeepers in the UK and Canada have seemed to have some success
Those having success have noted that they do not work well if the hives have a varroa infestation.
- I used them in July. Varroa numbers were already high.
- I wanted to see what they would do if one had varroa.
HOW MANY MITES TO USE:
High Tech Calculations
I found a range of suggestions on how many mites to use.
The U.K. sources suggested:
- 800 mites / hive every month in the dormant season (hives with no varroa)
- 1000 mites/hive every 2 months, from March to September
Remember these folks are starting with non-infected hives.
My mite supplier suggested 2,500 mites for an infested hive
Another test I found (and then lost the link, sorry) used
- 3,750 mites on a non-infected hive
- 6,250 mites on an affected hive – that is one-quarter of the tube of mites
As you can see, there were a lot of options from which to choose.
I opted for 4 different doses. One dose per each hive. These were approximately:
1,000 mites
2,000 mites
2,500 mites
6,250 mites
MY TEST: (finally eh?)
- First, I gently rotated the container, as instructed, to mix the predatory mites in the vermiculite
- Then I measured the mite/vermiculite mix with tablespoons and teaspoons.
Applying Stratiolaelaps scimitus Mites
- The mixture was placed on top of newspaper, as suggested by my supplier.
Mites on top of brood top bars
- The newspaper was placed on top of the highest brood box.
The test results:
The numbers that precede each result is the number assigned to the hive in the bee health survey.
The varroa mite count number is the number of mites/100 bees
| Hive | Dosage
(number of predatory mites) |
Mite count
Pretreatment July |
Mite count
Post-Treatment August |
Mite count
Post-Treatment September |
| 2 | 2,500 mites
(6 TB, 1.75 teaspoons) |
14.02 | 12.5 | 5.34 |
| 3 | 1,100 mites
(3 TB) |
6.29 | 10.19 | 21.45 |
| 6 | 2,200 mites
(6 TB) |
12.9 | 6.18 | 12.25 |
| 8 | 6,290 mites
(17 TB) |
6.92 | 7.11 | 31.09 |
Non-treated hives of the same period:
| Hive | No Treatments | Mite count
Pretreatment July |
Mite count
Post-Treatment August |
Mite count
Post-Treatment September |
| 1 | No treatments | 9.53 | 11.93 | 11.26 |
| 4 | No treatments | 2.77 | 9.39 | 15.66 |
| 5 | No treatments | 5.3 | 4.2 | 24.57 |
| 7 | No treatments | 4.36 | 5.25 | 23.76 |
DISAPPOINTMENTS ARE PART OF LIFE
Did the predatory mites work in hive Number 2? I have my doubts, as hive 8 had similar varroa numbers; it got a higher dose of mites yet the varroa count went up, dramatically.
If the predatory mites worked in hive Number 6, then they were effective for only one month.
OK, I was bummed. I really wanted these little mites, who already live in the US, to be the magic bullet that was going to get rid of the Varroa mites. The only other varroa predator I have heard of would have to be imported to the US, and that is a really, really bad idea : the importation of a non-native animal to kill a pest. That leads to environmental destruction and chaos (as we humans have proved time and time again).
THE DOWN SIDE OF THE MITES (in my humble opinion)
- They do not take up residence in the hive.
- They, apparently, must be applied repeatedly, beginning before varroa season
- They do not attack varroa inside of capped brood (the real problem area).
- They are not inexpensive I figured that the suggested rate for application in an affected hive cost (one quarter of the tube) is around $6.50/hive. Hop Guard is cheaper, and it, like the predatory mites, affects varroa out and about in the hive but not in capped cells
- They don’t seem to work in my hives.
ANYONE OUT THERE FIND THEY WORK?
If you or a beekeeper you know has used these mites and they worked. Do write and share. As I have often said, every hive is different; every hive location is different. My results show results on only for four hives, with varroa, here a remote corner of northwest Washington state.
WHAT HAPPENED TO THE VARROA IN FURTHER TREATMENTS
The hives are fine. I used other natural treatments in the fall. The results of those treatments are in the previous post LINK.
Brookfield Farm Bees & Honey Blog 
What a shame that you didn’t have positive results. Thank you for posting about your experiences.
But it seems you all have good results in the UK. But then their use on your side of the ocean starts with hives with little to no varroa… so perhaps that’s the key
Thanks from me too! I was also hoping these little guys would be a potent weapon. At least one of our club members is trying them out in 2014. Interesting to compare results.
Great – I hope you are able to let us know how that works out for your club member. Is s/he starting with low (or no) mite count?
Great information. Here is an eco floor that as Phil Chandler says “to enable Stratiolelaps to breed in the hive, as part of a balanced environment.” This is a top bar hive but he says it could be built for any hive design. https://www.youtube.com/watch?v=SWB-pdlqeFQ
That is really interesting. I wonder if anyone is using it and how it’s working for them. I have to say I immediately thought “small hive beetle home?” I know we don’t have them up here, yet, but they’ll probably get here :(. If you hear of someone using the eco-floor I’d love to hear about it.
The other issue is that there would be no sunlight that is required for the growth of algae and plant life that is part of their diet. Can they live without this? Also the mites like cool, damp conditions (60-70 fahrenheit) which are not ideal hive conditions and in nature they live their lives in soil. Would they crawl up the frames to feed on the mites? I will keep in contact with Phil Chandler in England to see how his eco floors are working.
That’s great I appreciate all the info, as I’m sure others do as well. – I had kind of hoped the SSmites would find their way to the ground through my screened bottoms (1/8″ hardware cloth), which sit about 6 to 8 inches off the ground (concrete blocks).
A positive video from Niagara Beeway (http://www.niagarabeeway.com/) on the use of Stratiolelaps. http://vimeo.com/63418711
Hi Bruce – Thank you for the link, on this wet dark day, I got a chance to watch the video. I wonder why they’re showing such a good result and I showed zip. I bought from the same company. Thee Niagara group clearly had mites already, as did I. The only difference I saw was that they put the mites on the top bars, but the company told me not to do that, and to use newspaper…. This is such a mystery to me. Thank you for the link. I’m going to share it on to the bee club here
Hi,
I am planning to try these this spring in the UK. Your results have caused me to waver slightly but I think I will plough on with the experiments. These things are biological and so many factors can effect the outcome; does that sound too much like blind hope ?
I am thinking on what I have read to do 1000 mites per hive once and then measure the results weekly over 8 weeks, or until I get bored if it does nothing.
I did wonder about giving them a soil floor to live in, but I don’t have enough hives to try that, I am doing 2 on mites, 2 on one chemical treatment, 2 on another and 2 with nothing.
Half the issue for me is ensuring no residue from previous varroa mite treatment (which would kill the nice mites).
Nice to see pictures of how to apply them, I had read before but photos are so much more… 🙂
Oh good, plow on with the experiments and let us all know what happens. As we all know, hives differ from apiary to apiary – weather, location, type of bee and on and on… I’d really love to see more tests done with these little mites – it would be so nice if they did work. I like how you are setting up your experiment – it will be very interesting to follow.
Really enjoyed reading about your experiment. I plan to use the Ss mite in my hives this year. I was wondering two things. Did you only treat your hives only once in July? If so, do you think it would be a good idea to try the experiment again using lower treatment doses more regularly. Finally, can you tell me if you know, how long do the Ss mites last in the container? Thank you
Yes, I only used the SS mites in July, when I had them – plus I had that lovely survey I was taking part in, so the “pros” did the testing. The people I got them from suggested the highest dose. Now, in the UK, where they’re used, it is suggested that you start treatments before the mites take hold — like in winter (if it’s warm), or in the early spring. I think that might work: let the SSmites build up along with the varroa numbers — My assumption was that they mites would die pretty quickly in the container. I got them, took them home, and put them in the next day — there’s nothing to eat in the container. But that was just my guess. Do let me know how they work out for you. I wasn’t impressed, but with a regular, earlier application, maybe they’d work.
After reading all this plus some other reports I’m going to knock the mites to their knees with oxalic acid in the winter as they do in the uk and then add mites in the spring and summer to keep them down. There is no magic bullet but I think a comprehensive approach using several types of control would be an improvement to using api strips.
They say oxalic acid works. Our local bee club (Mt. Baker Beekeepers Assoc) might be doing a demo this winter – I hope so. The only reason I’m reluctant is that I don’t like to mess with my hives here in the winter – it’s too wet and too cold. I would say that whatever you do – vary it from year to year (unless you’re going treatment-free, then stick with that if it’s working — nothing humans do kills every mite – some will survive and they will adapt to whatever is put on them….that’s evolution for you. So something different each year does not give them a chance to adapt…in my humble opinion. That’s why breeding is the best solution: then the bees evolve as the mites evolve…as it should be in nature
I like to use oxalis acid in the winter. It’s most effective when the hive is broodless, which in southern England is often around the time of the winter solstice – December 21st this year. The acid should be done very quickly – warmed beforehand in some hot water or an airing cupboard and then drizzled between each frame the cluster is on. It can be done in about a minute and then the hive roof whipped back on. Wear protection as the bees may not be happy to see you!
That’s a good summary Emily – I direct folks to your site about this (and other issues) – my local club might do a demonstration this winter. But I’ve still got this “hey there’s snow out here, I’m not pulling the top off” thing going. Maybe the demonstration will convince me….
I will be vaporizing with a vaporizer. I’m told this works better.
I’ll be interested to hear how that works out. But it’s still wet, yes? like a mist? I’ve got this bees-wet-in-winter-paranoia in this area.
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Very interesting, thank you for sharing your information! – vaporizing with oxalic acid is the most effective way to get ride of varroa, in my experience. You can get one from Heinz at: http://www.members.shaw.ca/orioleln/vaporizer.html. (he iis a beekeeper in our local club) All I know is that I used to really have troubles with varroa and used many methods were both not so effecive and toxic and I wanted to be an organic beekeeper – so by using a vaporizer and the thymol strips the last 5 years of beekeeping has been wonderful. This was big change from the first 6 years… (this is only an endorsement that it works, I have no pecuniary interest in the vaporizer) and for the many beekeepers that I mentor, it has really made their beekeeping more enjoyable. The only problem is that it is very dangerous to breath the vapor when you do it, so you have to wear a NOSH mask that works with VOC’c. Generally 3 times a year and thymol and things are good!
But doesn’t it get the bees damp? That’s my worry – I live in the land of “wet”, and I hate to do anything that makes their world even more damp.
No it is a solid that vaporizes when heated, then crystallizes in the hive covering everything with small oxalic crystals.
That’s interesting. Thank you. Do the bees then remove the crystals? Or do they just dissolve over time in the hive?