Sampling for Varroa Mites from a Honey Bee Brood Nest

Hello.

I'm Carolyn Breece, research assistant for the Oregon State

University Honeybee Lab.

We're at the OSU Apiary.

We will be demonstrating how to sample a honeybee colony

for Varroa mite populations.

It's September and it's a crucial time of year

to sample a hive for Varroa mites,

as the mite populations are increasing,

while the honeybee populations are decreasing

in preparation for winter.

We also want to know how well our late summer mite treatments

were effective and how the mite populations change

throughout the season.

Field Equipment

We will begin with the alcohol wash method.

The field equipment you will need to sample for Varroa mites

are your standard beekeeping equipment,

a wide mouth jar with a sealable lid,

and a cooler filled with ice.

First, smoke the entrance.

Open the hive and smoke the top bars of the brain.

All samples should be taken from the brood nests

where the mite count is most likely to be the highest.

Find a frame in the brood nest.

Make sure the queen is not on the frame

that you are sampling.

You can hand the frame to a second person

to double-check for the queen.

When you're ready to sample, brush

the edge of the jar along the backs of the bees.

Using long downward strokes, the bees will fall into your jar.

The right amount of pressure is important.

Too much pressure can damage the brood,

but too little pressure will result in an inadequate sample

size of bees.

Gather approximately 300 bees, which is about a half a cup.

You can take samples from multiple frames

if you don't collect enough bees.

Seal the jar and place in the cooler

until you can place the jar in the freezer.

Equipment needed for the mite count in the lab

includes ethanol, or isopropyl rubbing alcohol, a dish

for counting, and forceps.

Remove bees from the freezer.

Pour enough alcohol in the jar until the bees are submerged.

Empty contents of the jar into a dish and separate mites

from bees by washing.

Count mites and bees.

The number of mites divided by the number of bees

is the percent infestation in your colony.

Sampling

We will demonstrate the powdered sugar shake

method of a Varroa sample.

For sampling, you will need a wide mouth jar

with a 1/8 inch mesh screen lid, and powdered sugar.

First, smoke the entrance.

Open the hive and smoke the top bars of the frame.

All samples should be taken from the brood nest

where the mite count is most likely to be the highest.

Find a frame in the brood nest.

Make sure the queen is not on the frame

that you are sampling.

You can hand the frame to a second person

to double-check for the queen.

When you're ready to sample, brush

the edge of the jar along the backs of the bees.

Use long, downward strokes, and the bees

will fall into your jar.

The right amount of pressure is important.

Too much pressure can damage the frame of brood,

but too little pressure will result in an inadequate sample

size of bees.

You will be able to determine the right amount of pressure

after sampling a bit.

Gather approximately 300 bees, which is about a half cup.

Sift two tablespoons of powdered sugar, or enough to coat

all of the bees, through the mesh lid,

and roll the jar to distribute the sugar.

Let the jar sit for a minute.

With the bees still in the jar, shake all the sugar

into a container, preferably white,

and add water to dissolve the sugar.

Return the sugar-coated bees to the colony when done shaking.

Count the mites in the container and calculate the percentage

of mites over 300 bees.