We should have gotten to treating for varrora mites last weekend, but seeing as it was my Grammy’s 91st birthday she received all my attention. I love my Grammy.
Well we got to it today. Without needing to put the screened bottom board on, our latest check was purely visual with one frame with 10 mites. Consider 10 frames to the brood box … oy!
Varroa mites are nasty little bastards.
These evil little insects climb into developing cells, latch themselves onto larvae and begin sucking the life out of them (do you remember the Doctor Who episode when Donna had the beetle on her back and it modified her memories – well kind of like that and a Dementor from Harry Potter rolled into one jerk). But it doesn’t stop there. If a bee survives to adult then its wings will be severely damaged, likely not able to fly and bee a happy little forager. Poor bees!
What was that? These unrelenting Arthropoda are called Varroa destructor for good reason. When attached to a bee, these wee bit ties spread RNA viruses such as the deformed wing virus (DWV) . If enough of the hive is infestation it will lead to the death of the colony, usually in the late autumn through early spring. There is some thought that mites contribute to CCD (colony collapse disorder). They certainly do not help the health of a hive.
We’d better get a move on!
Possible ways of monitoring for mites include these OMAFRA guidelines.
2014 OMAFRA Varroa Mite Threshold Levels
The following are treatment guidelines. These suggested levels will vary depending on colony strength, apiary location and management. The best way to determine the proper timing for treatment solutions is to monitor regularly and compare results. In most cases, beekeepers must treat in both spring and fall to effectively manage varroa.
Table 9. Threshold guidelines for varroa mite levels in May and August.
Treat when varroa levels are equal or greater than the following:
Ether Roll 1 mite/100 bees 2 mites/100 bees
Alcohol Wash 2 mites/100 bees 3 mites/100 bees
Sticky Board 9 mites/24 hr drop 12 mites/24 hr drop
Alcohol Sample: Place approximately 150 bees per bee yard or 50 bees per colony into a container with alcohol
If you managed to read through that, we typically use screened bottom boards with sticky paper. We do not like to sacrifice our ladies for the greater good. Well, luck had it that we had purchased oxalic acid to mix with sugar syrup but in our recent spring clean up we seemed to have misplaced the bloody container. But we did have a box of MiteAway Quick Strips which are cotton pads soaked in formic acid. We placed one formic acid pad in the centre of each hive as the temperatures have been generously above 10C.
Mites reproduce on a 10-day cycle. I hate varroa mites.
We are trying to treat as organically as possible, so with our smaller nuc (remember Joe’s bees?) we quickly fixed our mistake and removed the pad from the five frame box (although with some death – sorry girls!) and applied icing sugar powder to the top of the frames. A nice dusting produces “Ghost Bees” the most eerie and yet, cute effect ever.
Now a lot of the powder just gets blown away, but it encourages the bees to groom each other eating yummy icing sugar and removing some of the varroa. We will continue dusting but will have to employ other methods as there is little evidence to show that this single treatment will control mite populations. It has about a 36% efficacy rate. That is low.
This weekend we’ll put on the screened bottom boards so if any mites fall they will go to the ground and not just crawl back up onto bees. This will also allow us to do proper mite counts via a sticky board.
This poor weak colony. If it survives, and the queen mates, it will be a miracle. At least we are learning something, right?
Another alternative is using Thymovar (thyme oil soaked into cardboard and placed in the hive). The essential oil will evaporate and is highly toxic to varroa mites but concentrations are not high enough to harm the honey bees.
Would varroa mite populations be lower with plantings of fresh thyme around the hives?
Other naturally occurring chemicals
- Sugar esters (Sucrocide) in spray application
- Oxalic acid trickling method or applied as vapor
- Mineral oil (food grade) as vapor and in direct application on paper or cords
- Natural hops compounds in strip application (Hopguard)
A combined application of Thymovar with an oxalic acid treatment in the broodless time (November – December) has proved very efficient against the Varroa.
Lastly as previously mentioned, mites lay in developing brood with preference to drones, so we have drone boards in the hives which once built up, we will remove and freeze – killing the mites (and sadly the bees). When replaced the workers will clean up the dead and the queen can continue laying drones. Over time we kill drones, but we also kill adult and developing mites.
We’ll keep you posted on our efforts. And like I said,
Varroa mites are nasty little bastards.