How To Test For Varroa Mites [3 Ways]

Varroa mites multiply quickly, spreading bee viruses through the colony. These pests are a significant threat to honey bees and will wipe out colonies that aren’t treated in time.

There are a range of effective varroa mite treatments available to beekeepers. However, nothing will help your bees if you don’t know how to identify mites at an early stage. In this guide, we provide step-by-step instructions to test for varroa mites.

Be sure to also check out our essential guide to treating varroa mites.

How do I test for varroa mites?

Beekeepers have a range of testing methods available to detect varroa mites. The most popular options are the sugar shake, alcohol wash, and sticky board drop. Keep reading to find out how it’s done.

1. Sugar shake method

The sugar shake method is a surveillance method that detects varroa mites along with other parasites like Braula fly and Tropilaelaps mites.

This method won’t kill your honey bees and is quick and easy to carry out. The sugar dislodges the mites, making examination and number counting much easier. 

You’ll need a jar with a mesh lid to keep the bees in.

1. Pour clean water into a bucket until it reaches half full.
2. Add a heaped tablespoon of icing sugar to a jar.
3. Open the hive to be tested and place the upturned lid on the ground. Add a puff of smoke to help calm the bees.
4. Collect a sample by shaking bees from three separate brood frames onto the hive lid.
5. Scoop half a cup of bees (300 bees) into the jar and replace the lid to stop any bees getting away.
6. Slowly rotate the jar for 2 minutes until the sugar has dusted all the bees. Allow two minutes, then continue gently rotating for another 2 minutes.
7. Shake the sugar into the bucket of water and wait a few seconds to see if any mites float to the surface.
8. Set the bees free on the ground next to the hive entrance.

That’s all there is to it. Of course, if you discover varroa mites your job isn’t over. Be sure to get busy treating the hive to get your colony back to full strength.

Quick tips for the sugar shake method

• When shaking the sugar into a bucket, be sure to do it in a sheltered place away from gusty winds.
• Take extreme care to ensure the queen isn’t part of your sample.
• If the hive has no brood for collecting the bees, get your sample from one central comb where the bees are clustering.

2. Alcohol wash method

Although some beekeepers use this method we don’t endorse it. Why harm bees when there are other less invasive options?

1. Remove the lid of the hive to be tested and place it upside down on the ground. Puff a little smoke to help calm the bees.
2. Shake some bees from three separate brood frames onto the hive lid.
3. Scoop 300 bees, about half a cup, into a wide mouth jar and cover the top with a mesh wire lid to stop any bees from escaping.
4. Pour in 70% alcohol or soapy water and shake gently for one minute, then pour the liquid through a cheesecloth or coffee filter.
5. Count the number of mites that get trapped in the filter. 

3. Natural drop method

Varroa mites will occasionally fall to the bottom of the hive. This allows beekeepers to insert a white grid board designed to help check for varroa infestations.

1. Apply a thin layer of cooking spray or petroleum jelly to the top side of a grid board.
2. Insert the board under the screen bottom and leave it for 24 hours before removing it.
3. Inspect the board and count the number of mites or other pests that are visible.

If you use the natural drop method, only leave the board in the hive for 24 hours. The reduced ventilation in the hive will agitate the bees.

There are special sticky liners that you can purchase from any good beekeeping supplier. They’re a good alternative to using oil or other sticky substances for catching the mites.

How to identify a varroa mite

The varroa mite (Varroa destructor) is a parasite that lives externally on honey bees and their brood. They have a flat oval-shaped body that is similar in size to a pinhead (1.1x 1.7mm).

Although these reddish-brown mites are visible to the human eye, they often burrow into hard-to-see places between the bee’s exoskeletal plates.

A beekeeper shouldn’t rely on visual testing when checking a hive for varroa mites. In the early stages of development, these mites mostly live inside capped brood cells so you won’t see them.   

Symptoms of a hive infested with varroa mites

During routine hive inspections, you should check for signs that varroa mites are present. Here are some symptoms to watch out for. Be sure to use one of the above detection techniques if you suspect an infestation.

• Are bees showing signs of deformities like poorly shaped wings or short abdomens?
• Do any white larvae have red or brown spots on them?
• Can you see any mites trying to hide between the adult bee’s abdominal sections or behind their head?
• Is your hive showing signs of weakness or suffering from losses?

If you don’t see any of these symptoms then it doesn’t mean your hive is free from varroa mites. A proactive approach is essential to minimizing colony damage.

How to calculate the severity of the varroa mite infestation?

Calculating the proportion of bees that are infected helps the beekeeper understand how severe the varroa mite infestation is. Don’t worry, you don’t need to be a math genius to work this out!

Infestation percentage = number of mites/number of bees.

If your test reveals 3 mites and you collected 300 bees, then the calculation would be 3/300=1%

How many varroa mites are too many?

The beekeeper must make a call on whether treatment is required based on the mite count. While many bee researchers suggest 50 mites discovered in a 24-hour is too many, other beekeepers will act if they discover 6 or more.

Ideally, beekeepers would love their hives to have zero mites. But keep in mind that most colonies with a low number of mites will often deal with the situation on their own. If they can’t, and numbers increase, that’s when a beekeeper should step in and help.

Why do I need to check for varroa mites?

Varroa mites are excellent at spreading viruses between bees within a hive as well as to other nearby hives. Deformed wing virus, slow bee paralysis virus, and acute bee paralysis virus are all transferred by these pests.

An infested colony will usually produce less honey and is more likely to pick up secondary infections. It’s in the best interests of every beekeeper to check for varroa regularly.   

Commonly asked questions

How often should I check for varroa mites?

At a bare minimum, beekeepers should test for varroa mites in early spring and late summer. During the bee season, it is best to check your hives once a month.

What natural remedies do varroa mites hate?

Varroa mites are repelled by pure thyme or mint essential oils. They will fall off the honey bee and won’t come back. It is a safe way to kill mites, even if honey supers are present.

What is a varroa mite test kit?

A varroa mite test kit is a simple way to test for external parasites without killing the honey bees. Although testing for parasites is possible with a few household items, these test kits include everything a beekeeper needs in one handy box.

Summing up

Varroa mites are one of the biggest threats to the honey bee population. They reproduce fast and are capable of spreading viruses from one hive to the next via drifting and robbing bees.

An essential part of beekeeping is testing for varroa mites. You need to know if hive treatment is required; it’s also important to test after treating a colony to find out if it worked.

If you’re new to beekeeping, you may also like to attend a local course or get some assistance with testing for mites. Getting it right from the outset will help your odds of managing a healthy apiary.