Ways To Treat A Hive With High Varroa Mite Count

The Varroa mite. That's the buzz these days...

And there’s a pretty good reason why!

If you’ve read our previous post on, ‘The Best Way To Test Your Hive For Varroa Mite’, you now know how to test your hive for this mite and that this little creature kills and makes your bees abandon the hive if you don’t take necessary actions in time!

If your hive is tested and you got a high Varroa mite count, it’s time to get on your feet. There are several techniques and products you can use to get rid of this destructive pest. You can use a chemical, mechanical or cultural approach to help your bees fight the Varroa mite.

Varroa mites reproducing throughout the spring and summer usually result in a larger mite population in the fall. And a chemical approach is the best way to address this issue before the production of your winter bees starts. You can use either soft chemicals or hard chemicals in this approach. If you use this method, first try applying soft chemicals and then move into hard chemicals if needed.

Soft chemicals

Naturally derived chemicals like essential oils, organic acids and hop beta acids are soft chemicals and unlike wax, these treatments do not leave any chemical residues in your hive.

Formic acid: this acid is a natural component of honey that occurs in the venom of honey bees. At high concentration levels, it penetrates the wax cappings and kills reproducing mites effectively. But it can cause serious damage to your colony if used at ambient temperatures (higher than 85F) since it can increase brood mortality, and if used below 50F, it results in lower efficacy.

Oxalic acid: this is also a natural compound that can be used for mite control. It’s most effective during broodless periods as it doesn’t penetrate the cappings. So, winter or early spring will bee a good time to apply this method. 

Thymol: for varroa mite control, thymol can be considered a widely used essential oil. But it cannot penetrate the cell cappings. Therefore, it’s unable to control mites in brood cells. And given its scent, thymol treatment can also inspire robbers and increase aggressiveness in the hive.

Hops beta acids: this is a treatment you can use any time of the year. But it’s effective when you use it when there’s less brood, as it doesn’t go through the cell cappings. But the efficacy of this method is not as high as other soft chemical treatments.

Hard chemicals

Using hard chemicals may be effective and kill around 95% of the mite population. But, if we take chemicals like fluvalinate or coumaphos, their residues persist and accumulate in wax, which harms bees and makes the final products less preferable to the end user. Upon all that, mites have developed resistance to these chemicals so most likely these chemicals are out of the picture.

Amitraz: some metabolites of Amitraz or Apivar(R) are persistent and powerful enough to effect viruses that are spread in your hive and linked to increased bee mortality. So, you can apply this chemical to help your bees in desperate times.

Mechanical approaches to treat your affected hive include drone brood removal and powdered sugar treatment which may sound familiar to you from our last post.

Drone brood removal

This technique uses mites' preference for drone broods for reproduction and makes a trap out of it. You can add a drone comb to your colony to encourage drone production that also acts as a trap for mites. You can then remove the comb before the drone emergence. It will effectively remove the Varroa mites reproducing in its cells.

Powdered sugar

Sprinkling powdered sugar on your bees can serve as a technique to control mites, as it stimulates bees’ grooming behavior which results in more mites on your bottom boards.

Using cultural approaches to mitigate and prevent Varroa mite population is aimed at pest reproduction.

Brood break

You can perform a brood break in the colony that can impact the availability of brood cells for mite reproduction. You can try this by caging or removing the queen from the colony for not more than 3 weeks. All of the brood will hatch during this time period and the mites will be forced out of the cells. This will affect the population growth of Varroa mites. Since the absence of brood increases grooming behavior of bees, mite population will fall during their usual hussle in the hive as well.

To make it more effective, we recommend you don’t stick to one method, but try in combination to treat your colony fast, so that your hive won’t be compromised and your bee-friends don’t have to abandon their home!

Sources:

https://www.extension.iastate.edu/smallfarms/managing-varroa-mites-honey-bee-colonies

https://sfyl.ifas.ufl.edu/media/sfylifasufledu/osceola/documents/agriculture/varroa-mite-control.pdf

http://www.simonthebeekeeper.co.uk/blog/varroa-mites-and-how-to-treat-them-n5

http://extension.msstate.edu/publications/managing-varroa-mites-honey-bee-colonies