Our local club held a Mite Assessment Workshop in my yard this past weekend, so thought it might be a good time to review my mite status. I’m a little laid back when it comes to Varroa mites. I only use organic compounds, and only when my counts exceed my threshold.
This was actually our second workshop of the year. We had one in April, also in my yard. I try to check the hives once a month, and having workshops in my yard in April and August certainly helps me keep up!
The classic bees vs mites curve, shown below with caption from Randy Oliver’s Scientific Beekeeping web site, illustrates the problem. After the summer solstice in June, the bee population ramps down in preparation for winter. The mites keep chugging along, and without an intervention the mites overwhelm the bees in fall or winter.
The main problem with Varroa, of course, is the viruses they vector. Like mosquitoes, which transmit Zika, dengue fever, malaria, and other diseases into humans, Varroa mites transmit deformed winged virus (DWV), acute bee paralysis, and other viruses into honey bees. That’s why humans work to keep the mosquito population down, and why beekeepers should work to reduce mite populations.
In any case, back to my hives. I captured one swarm and have made some splits, so I now have 9 hives. Here is a table of my mite checks in 2019. This shows the number of mites seen per 300 bees. I use a threshold of 2%, which is 6 mites from my roughly 300 bee sample.
|Hive Name||Apr 28||May 18||Jun 30||Aug 25||Notes|
|Venus||13||1||–||–||Treated with Formic May 4, removed May 12|
|Pandora||2||–||3||34||Treated with ApiGuard Aug 25|
|Calypso||3||–||10||0||Treated with ApiGuard Jul 21, added ApiGuard Aug 4, removed Aug 18|
|Mercury||–||–||1||–||Ran out of time, didn’t check|
As you can see, I had a high value (10) in Venus on April 28, and another in Calypso (13) on June 30. Since these exceeded my threshold of 6, I treated Venus with Formic Pro, and Pandora with ApiGuard. The subsequent reading in each of these hives verified that my treatment worked well.
In our workshop, there are few high readings, but Pandora really stands out with 34 mites, which is over 11%. Readings above 18 (6%) are considered a likely winter death. Perhaps these bees had drifting from Calypso (right next to her) or picked up mites elsewhere. Replacing this queen is a good idea, since her workers clearly do not handle mites well and we don’t want to preserve such terrible genetics.
I should point out that a high value like this is also problematic because even with a solid treatment mites are left behind. Say we kill 90% of mites, that leaves 10% in the hive. So starting at 34, we should still see 3-4 mites per 300 bees in a subsequent test. This is why I treated right away with ApiGuard, to get this started, and I will consider a follow-on treatment of Formic Pro. I will definitely look to replace this queen at my first opportunity.
My top bar hive row, with Saturn, a medium nuc, Titan2, and Venus, all had a reading near 6. I need to get some Formic (I am out) so I can treat these hives, as this time of year the numbers will only rise. We didn’t test Venus because her bees are a bit aggressive and I didn’t want to open her up around visitors. I need to replace this queen as well, I think.
Even though the other hives tested okay, I will check them again soon, especially Venus and Mercury. In the fall mite counts can rise rapidly, and with a “mite bomb” like Pandora nearby drift can be a real problem.
By performing regular checks, I have a sense of which hives are faring well (most of them) and which ones are a problem (Venus and Pandora), so this will help me decide some strategies going into winter.
This popular song from the musical Grease is about the summertime affair between the main characters Danny and Sandy. The most popular version of the song was performed by John Travolta and Olivia Newton-John in the hit movie released in 1978.
For my bees, the days and nights have certainly been hot and heavy lately. This past week is the first time we’ve had daytime temperatures regularly below 90 F (32 C) for a while. When I though of our hot summer, this song just popped into my head. So it seems an appropriate metaphor for this particular post.
May you prosper and find honey.