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Find The Varroa Mite

Let’s play a game. You’ve seen Find the Queen all over Instagram, but I’ve got a new one for you that’s been popping up lately- FIND THE VARROA MITE! Take a look at the picture below. We’ll reveal the answer at the end of the article. While you’re reading, watch out for clues to help you find the mite in the picture!

Disclaimer: There are several parasites and mites that affect honeybees. For the purposes of this post, I will use “mite” when reverencing varroa destructor.

Where did varroa mites come from?

In 1967, they were found on imported European honeybees in Hong Kong and Singapore. They began to spread through apiaries across Asia and Europe, eventually reaching the U.S. in 1979. At that time, one mite was discovered in a hive in Maryland. By 1987, Wisconsin and Florida were reporting sightings. Until recent, Australia and parts of Africa were varroa mite free; however, last year (2022) varroa mites were discovered in Australia. Efforts are currently underway to eradicate them.

How do they spread from one hive to another?

Honeybees rob resources from other hives. Mites will hitch rides on the bees and jump to new hosts once they’ve reached a new hive. And though never seen, there is reason to believe that mites may fall off of bees during pollination, waiting on flowers for their new host to arrive.

The life cycle of varroa mites.

*Varroa mite life cycle. www.extension.org*

Varroa mites’ reproduction cycle is closely tied to the brood-rearing cycle of the host bees. Female varroa mites enter the brood cells of honeybee larvae and attach themselves to the developing pupae 1-2 days before the cell is capped, where they feed on the hemolymph (insect blood). About 60 hours later, she starts to lay, on average, 2 eggs per day. These eggs take 3-9 days to mature, depending on their sex. Worker brood is capped for 12 days, whereas drone brood is capped for 15 days. As a result, varroa mite reproduction is closely linked to the production of drone brood, as they require the longer development time to complete their own reproductive cycle.

Here’s some trivia for you. It takes 16 days for a queen to hatch (the fastest development of any of the bees developed in a hive). That amount of time does not suffice for varroa mite development, so it would die. There is speculation, too, that mites are put off by the smell of royal jelly, so they will not even lay eggs there to begin with.

Where are you most likely to see them in the hive?

Outside of brood cells, varroa mites can be found wedged in between the armored plates in the thoracic cavity of adult bees, continuing to suck hemolymph like little vampires, weakening the bees and leaving them susceptible to infections.

What’s the big deal?

https://beekeepingabc.com/what-to-do-with-a-dead-beehive/

The presence of these mites is a significant concern, as untreated infestations can decimate entire bee colonies. Considering that an average colony houses around 60,000 bees, the potential impact is substantial. Varroa mites can severely impair the health of bees, leading to a reduction in the productivity of the hive. When colonies become overwhelmed with these parasites, it's referred to as Parasitic Mite Syndrome.

How can you test for them?

https://backyardbeekeeping.iamcountryside.com/health-pests/catch-and-release-powdered-sugar-roll-varroa-mite-test/

The powdered sugar method is a favorite among beekeepers as it is a non-invasive technique used to estimate the number of varroa mites in honeybee colonies.

This method entails putting 300 bees (1/2 cup of bees) into a canning jar, lightly filled with powered sugar, that’s topped with a wired mesh in place of the solid plate lid. You shake the jar around, coating the bees in the sugar, which causes the mites to lose their grip and fall off the bees. While turning the jar upside down, the dislodged mites fall through the mesh and onto a plate below. The number of mites on the surface is then counted to determine the mite load of the colony.

Here’s the math: if 10 mites are counted = 10 mites/300 bees = .03 = 3%. Now, take into consideration that mites lay eggs in brood cells, so what you just counted was just the tip of the iceberg, as in, most are hiding under capped brood. As of Spring 2018, experts have used 3% as their threshold for treating for varroa mites. So in our example, it would be a good idea to go ahead and treat.

This method is relatively easy to perform and does not require any specialized equipment, making it an accessible option for beekeepers to monitor the health of their colonies.

How do you treat your hive for varroa mites?

Now, do you have to test before you treat? Nope. Chances are, you already have the little devils in your hive. Testing gives you a reality. Does it harm the bees to treat them? Not if you treat as instructed. The harm comes from overusing this treatment, which can build the mite’s tolerance. So, don’t just think of your hive. Think of your bees going to other hives and transferring oxalic-resistant mites to them.

Oxalic acid has been the go-to, most effective treatment against these mites. One treatment of oxalic acid has proven to kill more than 95% of mites in a hive. The process is done through the vaporization of oxalic acid in the hive. The treatment works by creating a toxic environment for the mites, causing them to die off while not significantly impacting the bees. It is generally recommended to treat colonies with oxalic acid during periods of low brood activity, as this is when mite populations are at their lowest, making the treatment more effective. For most beekeepers, this means treating colonies in the late fall or early winter, after the bees have completed their brood-rearing cycle for the season. Another beneficial time to treat is in early spring, killing off any mites that may have survived the winter.

**For more information, read our blog post Effective Varroa Mite Treatment: A Guide to Using Oxalic Acid Vapor for Beekeepers

Did you find the varroa mite?

Here’s the picture again. Based on the above information, it’s no surprise to find the mite on this frame. There’s brood. Also, did you spot the queen at the bottom right? No surprise to see her here either.

Here’s another photo, but a little trickier. Give it a go.

Answer: Find the queen. Look 3 bees to the right of her. Look at the thoracic cavity of the bee.

Thanks for playing! If you want to learn more about beekeeping- no matter the space- follow us on Instagram (@thebeeuchanans) or send us an email with any inquiries!

References:

Burlew, R. (2016). Reduce varroa mites by culling honey bee drones. Honey Bee Suite. Retrieved February 25, 2023, from https://www.honeybeesuite.com/reduce-varroa-mites-by-culling-honey-bee-drones/#:~:text=The%20mite%20eggs%20take%20somewhere,cell%20will%20yield%202.4%20mites.

Jones, R., & Sweeney-Lynch, S. (2011). The beekeeper's bible: bees, honey, recipes & other home uses . Stewart, Tabori & Chang.

(n.d.). Varroa mites. Bee Aware. https://beeaware.org.au/archive-pest/varroa-mites/#ad-image-0

Reid, B. (2004). Varroa Mite (Varroa destructor). Introduced Species Summary Project. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/varroa_destructor.html

The History, Detection and Treatment of Varroa Mites