The Importance of Timing in Varroa Mite Management

In our PerfectBee Snippet series all about the feared Varroa mite, we’ve covered what the Varroa Destructor mite is, how mites can transmit viruses that can harm our honeybee colonies, and how you can go about managing mite infestations by using an Integrated Pest Management system.  

We’re now tying them all together to talk about the importance of timing when it comes to Varroa mite testing and treatments. We all know how much timing and biology play a role in most beekeeping tasks. Managing Varroa mites is certainly no exception! 

The Correct Sampling Process & Timing

To estimate, as accurately as possible, the number of Varroa mites that are present within a beehive, the beekeeper should ensure they are testing the right kinds and number of bees. Regardless of whether you’re collecting a sample of bees for a sugar roll or alcohol wash, you’ll need about 300 bees or about ½ cup of bees (lightly packed).  

Keep in mind that an alcohol wash test does kill the sampled bees, so although it is less accurate, the sugar roll test method may be preferred for smaller or weaker colonies to avoid sacrificing all of those integral nurse bees.  

Since varroa mites reproduce and live primarily inside honeybee brood cells, those 300 sampled bees should be taken from frames that are within the brood nest, specifically on frames that have open brood and older larvae. 

Mites prefer to hang out on nurse bees that are taking care of larvae just about to be capped. Just before the cap is added, they hop off of the nurse bees and sneak into the cell to feed on the developing bee larva and reproduce inside the cell.  

Take great care to ensure the queen is NOT included in your sample of 300 bees! If she is on a frame that has open brood, move her to another frame and take your sample. Even the sugar roll method, though gentler than other methods, can still harm or kill a queen if included in the sample.  

Timing for Completing Varroa Mite Testing

Just like sampling the right bees can make a difference in the accuracy of your mite counts, testing for Varroa mites at the right time can make a difference in the effectiveness of your testing.  

Since varroa mite reproductive cycles follow along with honeybee reproductive cycles, higher levels of varroa are often found within honeybee colonies that are rearing brood. This means that the timeline for starting to complete testing and the acceptable thresholds for the number of mites found can vary based on your region and the times of year that honeybees are actively raising brood.  

During the late summer and fall months, both bee and developing brood cell numbers start to decline. Since fewer brood cells are open for mites to hide in, the mites move onto the remaining adult bees to overwinter. Varroa mite counts may spike by the end of fall since most mites in the hive are on bees and not in cells.  

With just one female mite inside a hive, mite levels can begin to increase quickly. Pay close attention to the brood rearing cycles of your bees, and begin your mite tests before brood levels, and therefore mite levels, begin to increase. For most areas of the U.S., monthly mite testing is recommended between the months of March through the end of October.  

You should consider testing all colonies in your bee yard once per month, but you should always test colonies that you suspect may have a higher mite load. Mites can spread quickly within an apiary from simple interactions, like two foraging bees on the same flower or when bees are drifting which is where they are caused to enter the wrong hive inadvertently. With larger apiaries, start by selecting a sample set of hives to test first, then determine whether testing and treatment are required for the rest. Even large, robust colonies that seem healthy often carry higher mite loads that could decimate them if left untested and untreated.  

Seasonal Impacts

Toward the end of summer and beginning of fall, especially in colder areas, honeybees will prepare to overwinter by doing one last push in brood rearing. These bees will be the “winter bees” that live through to see spring and help to keep the queen and colony warm in the cluster.  

It is integral to pay close attention to mite counts that may spike during this time of final brood rearing. Any mites left in the hive throughout the winter months will continue to decimate the adult bees as they transmit viruses and feed on bees’ hemolymph (or bee “blood”). 

Knowing what the mite levels are in your hive, and how they may change depending on the time of year and what’s happening inside the hive, can help you to get ahead of infestations before they have the chance to decimate a colony.  

Timing for Treatment Applications

If you’ve determined that varroa mite levels in your hive are above treatment thresholds, (we’ll go further into detail about this in an upcoming Snippet) you may determine it’s time to apply a treatment to your honeybees.  

The timing of applying treatment is important, and if a high mite load is detected you may feel like you need to treat them ASAP, possibly even the same day you complete a test.  

But be patient! The inspection and varroa mite testing you just completed was enough to introduce some stress to your colony. Bees take some time, roughly 3 days or so, to get back to their normal state after a beekeeper completes any type of in-hive inspection or testing. Adding a treatment directly on top of that can add additional stress and increase the risk of damage to the bees, brood, or queen. It even causes the colony to abscond (where all bees in the colony leave the hive together) in some cases.  

Planning Ahead

This is where the importance of using an Integrated Pest Management system to plan out your varroa mite management can be a huge benefit to combating infestations. By knowing when your honeybees may have an increase in reproducing brood, you can introduce proactive measures and plan to have the right treatment close by before mite levels spike and get out of hand.  

Honeybees and Varroa mites follow the same phases in population cycles throughout the year, so get out your calendar and take note of when your honeybee colonies are active in raising brood, when they are experiencing a decrease or increase in population, and at what times of year they typically are at their peak in population. 

Keeping these types of records and notes throughout the season, and talking with other local beekeepers, can give you an idea of what usually happens in the hive and when, making it much easier to plan for upcoming seasons.  

Timing for Re-Testing After a Varroa Mite Treatment 

After you’ve decided mite levels require treatment and you’ve applied it, you’ll want to know if that treatment was effective. To find that out, you should complete another sugar roll or alcohol wash to find out what the hive’s new mite count is. 

Don’t complete another test too soon, though! Beekeepers completing inspections, doing mite tests, or applying mite treatments can have quite an impact on the bees inside the hive. It’s best to wait at least two weeks or so after adding treatment before going back in to complete another mite test. Giving the bees time to readjust, and for new nurse bees to be born, can make for more accurate mite counts, and can certainly make things easier for both you and the bees.  

Keep an eye on your inbox for more PerfectBee Snippets about Varroa mites, on topics like further understanding mite counts and applying treatments.  

Learn More

We’ve compiled some of our free resources below, with articles, guides, lessons, and blog posts specific to the dreaded Varroa Destructor Mite.   

As is the case with most beekeeping tasks, there are special tools and pieces of equipment that can help with managing Varroa mites in your bee yard. Check out the PerfectBee Store to find all of your Varroa mite testing, management, and treatment needs. Here are a few of our favorite options: 

  • Varroa EasyCheck – For measuring a mite count using the alcohol wash method. 
  • Sugar Roll Testing Kit – For assessing mite count using the sugar roll method. 
  • Oxalic Acid Kit – A kit that gives you all you need to complete an oxalic acid dribble 
  • Drone Frame – Adding a drone frame to your hive can help manage varroa mite levels, but only if timed perfectly right before the drones inside emerge and a ton of mites emerge with them! 
  • The Langstroth Screened Bottom Board and Varroa Monitoring Tray – Use the screened bottom board with tray to take a 24-mite count by counting how many phoretic mites fall off of bees within that time period 
  • A Field Guide to Honeybee Maladies – An excellent guide to many honeybee viruses, diseases, and pests. Includes information and photos of Varroa Mites and the issues they cause. 

Colony Member Resources

Colony members, check out these member-only Academy lessons to learn even more about Varroa Mites: 

And login to the Colony Forum to view some interesting discussions specific to Varroa Mites: