Mite Management in Top Bar Hives

Mite management of top bar hives

The varroa mite does not care that you’re keeping your bees in a top bar hive–colonies in top bar hives are just as susceptible to the mite.  Unless you are running a truly mite-proof bee stock, you can expect the same sort of buildup of mite populations as in Langstroth hives in late summer, and I have seen plenty of top bar deadouts with clear signs of mite overload.

You will still need to knock the mites back by 90% at least once, and generally twice a season, depending upon your circumstances.  Perform alcohol washes or sugar rolls to monitor your mite levels.

Unfortunately, the lack of space between the top bars makes mite management a bit more difficult than with Langstroth hives, since there would be little bee or vapor movement downward from treatments applied above the broodnest, and oxalic acid solution can’t simply be dribbled into the Langstroth frame interspaces.

However, that doesn’t mean that you can’t apply mite treatments, although depending upon the exact configuration of your top bar hive, you might need to use some ingenuity.  I have zero personal experience with mite control of TBHs, so the following information has been largely gleaned from others who know what they are talking about.

Some Options

Strip Treatments

Dr. Wyatt Mangum, a pioneer of TBHs, no longer finds mite treatment necessary, since he runs resistant bee stock, but he suggests that strip treatments can be applied between the top bars, at the same rate, according to colony strength, as in Langstroth hives (typically 1 strip per 5-10 frames of bees).

Synthetic Miticides

The strips currently available would be:

• Apistan (a synthetic miticide that accumulates in the beeswax, and to which some varroa populations are resistant).
• Checkmite II (an organophosphate that I can’t bring myself to recommend).
• Apivar (the same chemical used in dog tick collars). Apivar should be highly effective against the mites coming from my hives, since I’ve never used the active ingredient.
• Hopguard (a “natural” miticide, organically approved). This treatment may need to be repeated for effective mite control.

Essential Oils

Don’t waste your time.  Bees generally find essential oil treatments to be stressful, and other than thymol, have little effect upon varroa.

Thymol

Apiguard gel can be used effectively, and is organically approved.  For efficacy, the bees must have access to the gel particles, and carry them through the hive (there is very little vaporization).  Thus, the gel must be placed such that the cleaner bees carry it throughout the hive.  You can place 50g below the combs, but might get better results if you can figure out how to place it someplace else that bees will remove it.  Please let me know if you find a method that works well.

Formic Acid

Formic acid is excellent for mite treatment—it’s organically approved, leaves zero residues, works fast, and is the only treatment that penetrates the cappings of brood cells.  Formic acid vapors are denser than air, so it is best applied above the combs.  I suspect that it would work well if you were to spread the top bars slightly, and apply a flash treatment overnight.  You can remove the queen for protection, and keep her in a cage elsewhere during treatment, although young, vigorous queens are not generally harmed by formic treatment.

Unfortunately, formic flash treatment requires mixing formic acid with water and special application.  MiteAway Quick Strips (MAQS) on the other hand are available off the shelf.  They do a decent flash on the first day, but take 5 days for full treatment.  Some report success by applying them below the frames.  You’d likely get best results if you closed off screened bottoms during treatment.

Oxalic Acid

I really like oxalic acid, and Christy Hemenway covers the use of OA in TBHs fairly well in her book Advanced Top Bar Beekeeping.

.Although you can’t dribble as with Langstroth frames, you could temporarily spread your frames tiny bit and dribble between them.  Or better yet, invest in an oxalic vaporizer, close off any bottom screens, and apply vapor.  Vaporization might be easier, but is more potentially hazardous to the applicator.

The caveat with oxalic acid is that either treatment is only effective for about 3 days, and it doesn’t affect the mites in the brood.  Thus, unless you’re applying during a broodless period, either dribble or vapor must be repeated at 4-day intervals at least 4 times (dribble is stressful to the colony if applied that often).

If you are dribbling, adjust the dosage per comb relative to the size of a deep Langstroth comb (134 sq. in. per side), which takes 5 mL.

For best results with OA, apply only during natural or induced brood breaks (when there is no sealed brood in the hive).  An induced break can be created by splitting the hive or caging the queen for a minimum of 12 days.  The queen can be released after 12 days, and the OA needs to be applied before 8 days have passed since her release.  This method can result in over 90% mite kill.

Although not yet approved, the oxalic shop towels covered at https://scientificbeekeeping.com/oxalic-shop-towel-updates/ hold great promise for TBHs, if applied as some sort of strip (such as Strait-Flex  Drywall Shims).

Answers from two others

Kristina Williams (Boulder, Colorado)
I’ve successfully used MAQS or Apiguard on the on the bottom of the
hive.  I sometimes have to trim the bottom edge of 2-4 comb to get the
treatments to fit. If using Apiguard in the single serve trays, I dump it
upside down onto the foil cover, more like the bulk form.  Those trays are
just too thick.  I’ve used Hopguard II in a TBH.  It’s as effective as it
is in a US standard hive.  That is to say, not very, but it will keep the
mites down to a dull roar until the weather cools off somewhat.  I’ve used
OA vapor in January, but there has to be a slot type entrance for the
cooker.  Some TBHs only have bung holes.
One problem with treating a TBH is that there are no honey supers to
pull off.  I tell people to mark ALL the bars in the hive when Apiguard or
OA is applied as not-for-humans.  I put Hopguard only in the brood area.  I
put Apiguard far from the entrance so the bees have to carry it through the
hive.
There’s no standard size or entrance configuration.   For dosage of the
organic acids and thymol I estimate volume (they’re all different), and
sort of take into account the shape and how much air flow there is.   Some
are pretty congested with cross comb and attachment to the walls.  I
haven’t used an OA dribble, but it could be done IF the combs are free
enough to be moveable a half inch apart.
For monitoring, it’s a little tricky getting a sample off those combs,
especially the new ones. Maybe brushing bees into a tub and then scooping
up a half cup would be safest.  And of course the sugar shake is what most
prefer, at least to start.  Three to four years of dead bees will sometimes
change minds, though.
I have alcohol wash data before and after on my hive.  On other
people’s hives I have pretreatment data, but only whether the hive survived
or not for post treatment.  Generally they do survive if they’re treated
adequately.  My steady TBH customers are splitting hives, cancelling
package orders, and saying they don’t want more hives.  So, it can be done.
I have a talk with people about ‘natural’ treatments.  Plants and
insects are mostly enemies and those secondary compounds we like in our tea
are mostly made by plants to repel or kill insects.  So hold off on those
plant products unless they’re necessary, effective and safe for the bees
and you.  Add that lemongrass and wintergreen to your own tea.  It’s lovely.
I also try to point people at evidence based resources no matter what
type of hive they have – University, USDA, extension, your site – and away
from blogs, opinions, Facebook unless backed by the former.  Most people
really don’t know where to find good information.

Bill Hesbach (Connecticut)

The treatments that are most effective are HopGuard during bloodless periods with small populations. You can open the top bars and slip the strips in then move the bars back together – no problem.  The same is true for an OA dribble- separate the bars, dribble the seam and close them again. I don’t use Amitraz but I’d assume those strips could also be placed between bars. The easiest broodless treatment is sublimating OA. My TBHs allow rear access (see photo) so I can slide my varrox right under the cluster or place in the center of the colony.

During periods with brood I use MAQS.  I just slide the pads along the bottom board and position them under the brood.  Even though the formic acid vapors are heavier than air they seem to work just fine.  If you monitor the colony and keep the numbers low, same as you would in a lang box,  you get the same results- colonies that survive – I just split one two days ago after its third year.