Conduct an Alcohol Wash for Varroa Mite Monitoring

An Alcohol Wash is an Easy Varroa Mite Testing Method

November 22, 2019Kristi CookHealth & Pests

Conduct an Alcohol Wash for Varroa Mite Monitoring

Reading Time: 5 minutes

Successful beekeeping keeps colonies healthy and thriving year-round. In order to be successful though, management practices must consist of many facets. Properly timed feedings, requeening, splitting, and disease prevention are but a few of the necessary tasks. However, of all the checkboxes listed on a beehive inspection checklist, monitoring Varroa destructor’s infestation levels is arguably the most important — yet mite checks are also the most commonly forgotten task. This doesn’t have to be with so many fast and simple methods available. Of the many techniques out there, the alcohol wash for varroa mite counts is currently considered the most accurate and is both fast and simple after a bit of practice.

While alcohol washes are easy to do by yourself and require little equipment, I find washes much easier and faster with an extra set of hands. With one person helping, I can test about 10 or so colonies in an hour even when taking my time. Without help, I manage about half that. Try to pick a day when you know the bees should be calm, well-fed, and the weather is stable. Don’t attempt mite counts if robbing has occurred. Calm bees make the process so much easier. However, things don’t always go as planned, so don’t allow less than ideal conditions to keep you from those mite counts.

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As for equipment, bee supply stores carry various versions of alcohol wash kits. Kits include a cup-like container that holds 1-2 cups of rubbing alcohol, a strainer that holds the bees in the alcohol while allowing mites to drop through and some way of swirling the bees in the alcohol. However, for those who prefer to DIY, alcohol wash kits are simple to make and various DIY versions are readily found online.

Other equipment needed:
~ rubbing alcohol
~ small plastic tote, preferably with rounded inside corners to assist with scooping up bees
~ ½ c. measuring cup
~ tea strainer
~ glass jar for straining/storing alcohol

Dedicate equipment to mite counts, as propolis sticks to everything and renders cups, jars, and strainers unfit for the kitchen.

Be consistent with the equipment used, the amount of time spent swirling the bees, the location in the hive from which bees were selected, and the counting/recording methods.

Select a frame or two of brood covered in nurse bees. Alternatively, to avoid injury to brood, a frame or two of pollen closest to the brood may be used as nurse bees cover these frames as they feed nearby brood. Just remember to be consistent in the types of frames from which you pull nurse bees. Don’t forget to check for the queen! If you see her, replace that frame and grab another one.

Forcefully tap a corner of the frame inside the plastic tub to release bees. Or, gently rub the measuring cup downward along the frame to cause bees to fall into the cup. An advantage to tapping bees into the tub is to allow the foraging bees to fly out, leaving behind only nurse bees which are slow to fly and are also the most heavily infested adult bees. Also, by having the bees in the tub, the queen will be much easier to spot in the event you overlooked her initially. Once you have at least ½ cup of bees in the tub and you know the queen is safe inside the hive, tap the tub on its corner to force the bees to one side.

Once the nurse bees are corralled, gently run the measuring cup along the side of the tub scooping bees as you go. Fill the cup evenly, running a finger along the top of the measuring cup to encourage extra bees to fall back into the tub. Release extra bees back into the donor hive.

As soon as the cup is filled, dump bees into the alcohol solution and swirl a time or two to quickly submerge all bees to allow for a quick death and no fly-aways.

Swirl bees continuously for one minute to cause mites to release and drop to the bottom of the cup.

Remove strainer and place over tea strainer to drain into a glass jar.

Carefully count mites left in the jar/cup. Sometimes it helps to hold the cup up toward the sun and other times it’s best to place the cup over a white surface, depending on the lighting that day. The number of mites counted is per 300. So if you see 3 mites, you’d record it as 3/300.

Strain the alcohol through the tea strainer. The strained alcohol may be used repeatedly until mites are no longer readily visible as the alcohol darkens with each wash.

That’s all there is to conducting an alcohol wash! It couldn’t be simpler.

Once mite counts are noted, the next step, if not already completed, will be to learn when and how to treat varroa mites. Currently, the recommendation is to keep mite counts below 3% (below 3 mites per 100) with anything higher warranting immediate action. It is also recommended that beekeepers conduct a minimum of four counts per season to monitor for increasing mite loads as the season progresses. However, many choose to monitor monthly from early spring through the first freeze to keep a closer eye on mite counts.

Far too may beekeepers question the necessity of mite counts. However, confirmed mite levels allow the beekeeper to know which hives need treatment, which hives need second and third treatments, which hives are a lost cause, and even which hives exhibit mite resistance — a beekeeper’s dream. Plus, post-treatment mite counts show whether the treatment is effective, mediocre, or failing. As a major bonus, once you become accustomed to checking off that one little box on your inspection list, you’ll see an improvement in bee health and discover that preparing honey bees for winter becomes even easier as the healthier bees are better able to collect sufficient pollen and nectar for the winter while staying strong and healthy. And healthy bees always means fewer losses when all other facets to successful beekeeping are in their proper place.