Agricultural Innovations

Integrated Pest Management for Varroa Destructor 

in the Northeastern Un ited States using Drone Brood 

Remova l and Form ic Acid 

Nicholas W. Calderone

Cornell University

Introduction

T

his bulletin focuses on the management of the parasitic honey bee mite Varroa destructor (V. destructor) 

in the northeastern U.S. It contains information that will 

allow a beekeeper to: 1) identify V. destructor, 2) recognize 

the symptoms of mite infestation, 3) determine pest densities, and 4) implement an effective IPM program for keeping mite populations below the economic injury level. 

The western honey bee, Apis mellifera, was introduced to 

the U.S. from Europe in the 1600s. Today, the honey bee 

provides essential pollination services for over 45 commercial crops grown throughout the U.S., adding $14.6 billion 

to the value of the country’s agricultural production each 

year. In addition, U.S. beekeepers produce between 170 

and 220 million pounds of honey each year, more than 50% 

of total U.S. consumption. Hence, a sustainable supply of 

healthy and affordable honey bee colonies is a critical factor 

affecting farm productivity and the stability of farm incomes and food prices. 

The parasitic honey bee mite V. destructor (photo A) is 

considered to be the most serious global threat to beekeeping and to the sustainable production of crops that rely on 

(Introduction continued on page 2)

Inside this fact sheet:

# Introduction

# Origins and Distribution of V. destructor

# Symptoms and Damage of V. destructor

# Life Cycle of V. destructor

# Transmission of V. destructor

# Monitoring and Thresholds

# Rationale for IPM Program

# IPM Chemical Control Methods

# IPM Non-Chemical Control Methods

# Treatment Regimes

# Important Terms

# SARE Research Synopsis

# References

SARE Agricultural Innovations are based on 

knowledge gained from SARE-funded projects. 

Written for farmers and agricultural educators, 

these peer-reviewed fact sheets provide practical, 

hands-on information to integrate well-researched 

sustainable strategies into farming and ranching 

systems. The articles are written by project 

coordinators and published by SARE.

The methods discussed in this fact sheet were developed 

and evaluated in the northeastern U.S. Drone brood removal will benefit beekeepers throughout the U.S.; however, formic acid and other miticides acting as fumigants 

work best in areas where colonies are broodless or 

nearly broodless for at least four weeks during the fall or 

winter. When a colony is rearing brood, most mites are 

present in brood cells where they are protected from the 

effects of fumigants. During broodless periods, mites are 

present on adult hosts and are susceptible to fumigants. 

Since fumigants have a relatively short treatment period 

(about three weeks) compared to other pesticides 

(about six weeks), it is critical that the majority of mites 

be present on adult hosts for fumigants to be effective. 

GE O G R A P H I C RA N G E :

Fact Sheet Practical applications for

sustainable agriculture

PDF available at www.sare.org/publications/factsheet/pdf/02AGI2005.pdf

Sustainable Agriculture Research & Education

Photo A. A mature adult female V. destructor.
Integrated Pest Management for Varroa Destructor SARE 2

A. mellifera for pollination. V. destructor, which kills 

honey bee colonies of European descent within one to 

two years, has killed millions of managed and wild 

colonies in the U.S. in the past two decades. Apistan® and CheckMite+® have provided some relief, 

but control always has been unpredictable due to the 

fact that mite populations often rise rapidly during 

the honey-producing season, when treatment is proscribed by label restrictions. Consequently, colonies 

often suffer serious damage while the beekeeper waits 

for a legal treatment window to open. The threat 

from V. destructor has become a matter of grave concern as resistance to both Apistan® and CheckMite+® has become widespread.

To continue to be viable, the beekeeping industry 

requires sustainable management practices that will 

keep mite populations below the economic injury level and 

maintain the high quality of hive products. The best way 

to achieve these goals is to use a management program that 

relies on multiple tactics, rather than solely on chemicals. 

One such approach is referred to as Integrated Pest Management or IPM. IPM incorporates chemical and nonchemical tactics; however, for several reasons, IPM minimizes the use of chemicals whenever possible. First, 

chemicals add a recurring cost to a beekeeper’s management program. Second, chemicals inevitably show up as 

residues in hive products, and that jeopardizes their reputation as pure and natural products. Third, chemicals can 

be injurious to the applicator and may pose a risk to the 

consumer. This raises the issue of liability, especially for 

beekeepers with employees. Fourth, the less a pest population is exposed to a pesticide, the more slowly it develops 

resistance to that pesticide. So, by minimizing the use of a 

pesticide, its useful lifetime is extended. 

Origins and Distribution of 

V. destructor

V. destructor is an obligate parasite of cavity-dwelling 

Apis bees. It cannot reproduce on yellow jackets, wasps, 

bumblebees or any other species. Early reports of this mite 

on the western honey bee inaccurately identified it as V. 

jacobsoni Oudemans, which exists in a sustainable association with the eastern honey bee, A. cerana. In 2000, the 

genus Varroa was reported to consist of at least two species, V. jacobsoni (which infects A. cerana, but not A. mellifera) and V. destructor (which infects both A. cerana and 

A. mellifera). Consequently, literature reporting on V. 

jacobsoni and the western honey bee prior to that time actually refers to V. destructor. 

The association of V. destructor with the western honey 

bee reportedly originated in the 1950s, when mites transferred to A. mellifera colonies introduced to the home 

range of A. cerana. Subsequently, V. destructor has established a nearly cosmopolitan distribution with respect to 

its new host, with Australia being the only mite-free continent. V. destructor was discovered in the U.S. in 1987. 

Due to the highly mobile nature of both the honey bee and 

the U.S. beekeeping industry, V. destructor quickly became endemic, and it can now be found in every state in 

the continental U.S. 

Symptoms and Damage of 

V. destructor

An adult female, V. destructor is elliptical in shape with a 

width of 1.5 mm, a length of 1.0 mm, and four pairs of 

legs. Mature female mites are brown, dark brown, or cordovan (photo A). During immature stages, the bodies of V. 

destructor are light and translucent, but those attributes 

tend to disappear on adult hosts. Usually, there are no obvious symptoms at low levels of infestation. As the mite 

population increases, a suite of symptoms, collectively designated parasitic mite syndrome, becomes apparent. Initially, adult workers with damaged wings are seen (photo 

B). This damage is a result of DWV (deformed wing virus), which is introduced either directly or indirectly to the 

developing bee by the mite. 

As the infestation rate increases, more damaged workers 

are seen and otherwise healthy looking bees may be seen 

crawling in front of the hive, unable to fly. This condition 

is also caused by a virus. Finally, the brood begins to detePhoto B. A worker honey bee with deformed wings.
Integrated Pest Management for Varroa Destructor SARE 3

riorate, appearing to be infected with a variety of pathogens (photo C). Although these brood symptoms superficially resemble American and European foulbrood, the 

causative organisms of those diseases have not been identified in the deteriorating brood and treatment with antibiotics does not eliminate the condition. As the syndrome 

progresses, the worker death rate exceeds the birth rate, 

and most new worker bees that do emerge are seriously 

impaired. As a result, the colony’s population begins a 

rapid decline. From the time that a colony first exhibits 

brood symptoms until its total collapse can be as little as 

three weeks. 

Life Cycle of V. destructor

The life cycle of the mite can be divided into phoretic and 

reproductive phases. The reproductive phase begins when 

a mature female leaves her adult host, enters a brood cell 

containing a worker or drone larva shortly before it is 

capped, and sequesters herself in the bottom of the cell. 

Soon, the cell is capped; and shortly thereafter, the immature bee enters the pupal stage. Egg-laying commences 

about 60 hours after a cell is capped, and both mother and 

offspring feed on the host’s hemolymph. Mature offspring 

mate within the cell, but only mature females survive outside the cell. 

The number of offspring that reach maturity is positively 

correlated with the length of the host’s capped stage, 

which is greatest for drones, intermediate for workers, and 

shortest for queens. Mites that reproduce on drone brood 

average 2.2 to 2.6 female offspring per host, while those 

reproducing on worker brood average 1.3 to 1.4 female 

offspring per host. Mites cannot reproduce on 

queen brood due to its short capped period. Not 

surprisingly, mites are found more often on drone 

brood than worker brood, with average differences 

between 5- and 12-fold. Mites are only rarely found 

on queen brood. 

The phoretic phase begins when the host emerges 

from its cell as an adult bee. The mature female 

mite may leave the cell with its adult host, or it may 

walk out of the cell and acquire an adult host. 

Mites remain on an adult host for a few days or 

weeks before entering a brood cell for the next 

round of reproduction. Mites are found twice as 

often on bees in the brood nest as on bees in the 

honey supers, and 10 times as often on brood nest 

bees as on foragers.

Transmission of V. destructor

Robbing by bees is a major source of transmission. As an 

infected colony become progressively weaker, its defensive 

capabilities decline, and it becomes susceptible to invasion 

by workers from nearby colonies (the robbers) seeking its 

valuable cache of honey. In the process of removing the 

honey, robbers become infected with mites and transport 

them back to their own colonies. Swarms from infected 

colonies also contribute to the local reservoir of mites. 

These colonies are particularly susceptible to being robbed 

because they do not receive any treatment for mite control. 

They weaken and die within a year or two and may be 

robbed by workers from nearby colonies. Drifting bees, 

especially in apiaries where colonies are kept close together, also contribute to the spread of mites among colonies.

Beekeepers also play a major role in the transmission of 

mites. Moving brood among colonies for the purpose of 

strengthening or equalizing colonies is a common practice 

that transmits mites. In addition, beekeepers often purchase colonies of bees in the spring to replace winter losses 

or to increase colony numbers. Some beekeepers purchase 

small nucleus colonies, usually called ‛nucs,‛ from local or 

regional suppliers. These colonies consist of one to five 

combs of bees and brood and usually come with a queen. 

Others purchase package bees (2, 3 or 5 pounds of bees, 

usually with a queen) from a southern location. An estimated 1 million packages are shipped throughout the 

country each year. Each of these practices spread mites, 

including various types of pesticide resistant mites.

Photo C. Deteriorating brood typical with high levels of V. destructor. 
Integrated Pest Management for Varroa Destructor SARE 4

Migratory beekeeping 

also plays a role in 

transmitting mites. 

Over a million colonies 

are moved throughout 

the country each year 

as migratory beekeepers fulfill pollination 

contracts. After the 

bloom is over, colonies 

are widely dispersed to 

other locations for 

honey production. 

During the season, 

some of these colonies 

may issue miteinfested swarms into local environments, while others may 

succumb to mites and be robbed by local colonies. Each 

fall, surviving colonies are returned to a few states in the 

south where colony numbers are restored. This brings 

colonies from many different regions of the country into 

close proximity to one another and provides many opportunities for the transfer of mites among colonies, including 

various types of pesticide resistant mites. In the spring, 

these colonies resume their migratory routes throughout 

the country, and the process is repeated. 

Monitoring and Thresholds

Survey methods provide presence/absence information. 

One such method is the “cappings scratcher,” which requires one to impale a number of capped drone cells with a 

cappings scratcher, and then to pull the immature drones 

from their cells for examination (photo D). This 

method has been found to be highly effective in 

detecting mites when present at very low levels. A 

second survey tool is the “sticky-board,” which 

takes advantage of the fact that mites often fall off 

of bees. Typically, a piece of paper is covered with 

a sticky substance (petroleum jelly or a vegetable 

spray) and inserted into the hive where it rests, 

sticky-side up, on the bottom board. The stickyboard must be protected from the bees. One way 

to do this is to build a wooden frame, cover one 

side with 1/8‛ hardware cloth, and attach the sticky

-board to the other side (photo E). Sticky-boards 

are also available commercially. The board is removed after 24 or 48 hours and the mites are 

counted. Strictly speaking, the sticky board does 

not provide information about pest density; however, it is often used for that purpose. Lastly, mites 

can sometimes be 

seen on adult bees or 

walking on the comb, 

but this is more common when infestation 

rates are very high 

and should not be relied on as a diagnostic 

method. 

Sampling methods

provide an estimate of 

pest density. This is 

the type of information needed to determine whether to apply a pesticide. One method is the “ether-roll,‛ which provides an estimate of pest density in terms of mites per standard volume of bees. Bees are collected from two or three 

brood-nest combs and placed in a quart glass jar. If only a 

few colonies are being sampled, shake bees directly into a 

dishpan. Scoop up 1⁄2 cup of bees and quickly pour them 

into the quart jar. If larger numbers of colonies are being 

sampled, a modified ‚Dust Buster‛ (DC Insect Vac from 

BioQuip®) can be used to collect a standard volume of 

bees, which are then transferred to the quart jar. You will 

need to experiment with the vacuum collector to determine the exact volume that yields about 300 bees. Spray a 

three-second burst of an automotive starting fluid into the 

jar, replace the lid, shake vigorously for 10 seconds, and 

then toss and roll the jar three times along its long axis. 

Mites, if present, will be seen adhering to the sides of the 

Photo D. The ‘cappings scratcher’ method for surveying for mites.

Photo E. The ‘sticky board’ used for surveying for mites.
Integrated Pest Management for Varroa Destructor SARE 5

jar (photo F). This method detects 50 to 

60% of the mites actually present in the 

sample. The resulting ether roll count is 

usually converted to a standardized 300-

bee ether roll count (SER) using the 

formula:

SER = (ER) / (#B/300),

where ER is the ether roll count for the 

sample and #B is the number of bees in 

the sample.

An improvement in accuracy can be 

obtained by calculating the actual miteto-bee ratio. This is done by collecting 

the bees as above and then separating 

the mites from the bees by agitating 

them for five minutes in a container with soapy water or 

alcohol and straining through a 1/8‛ hardware cloth screen. 

The screen catches the bees but allows the mites to pass 

through. Typically, bees are washed several times to remove all of the mites. Mites and bees are counted and the 

actual mite-to-bee ratio is calculated. You can convert the 

mite-to-bee ratio to a standardized 300-bee ether roll count 

using the formula:

SER = ((R * #B) / 1.783) / (#B / 300), 

where R is the mite-to-bee ratio in the sample and #B is 

the number of bees in the sample. The conversion factor 

(1.783) is from Calderone and Turcotte (1998) [1].

Remember! For an estimate of pest density to be meaningful, each step in the sampling method must be standardized. This means monitoring mite levels at the same time 

each year, and monitoring all colonies exactly the same 

way. For the ether roll, this means collecting samples from 

the same place in each colony (tow or three brood nest 

combs), collecting the same number or volume of bees in 

each sample, applying the same amount of starting fluid, 

and shaking the jar in the same manner. For the stickyboard, the same size board must be used each time, the 

sample must be collected at the same time each year, and 

the board must be left in place for the same length of time. 

The decision to use or not to use a pesticide is based on an 

economic threshold. This is the pest density at which economic damage is expected if a treatment is not applied. 

Economic thresholds for V. destructor vary widely 

throughout the country. The values used below are based 

on studies conducted in the Midwest and Northwest, 

where blooming patterns, length of winter and winter temperatures are similar to those in the Northeast. Significantly different values are used in other parts of the country. Beekeepers should contact their local extension apiculturist for the most current recommendations for their area.

Rationale for IPM Program 

For a colony to survive the winter in good condition, it 

must have a strong population of healthy worker bees in 

the fall (photo G). A colony exhibiting early stages of parasitic mite syndrome in mid-summer can usually be saved 

by the application of an effective miticide because it has 

time to produce several more generations of healthy workers in a low-mite environment. However, in the northeastPhoto F. Mites adhering to the sides of a jar in the ether-roll test.

Photo G. A strong population of workers ready for 

winter.
Integrated Pest Management for Varroa Destructor SARE 6

ern U.S., these symptoms often occur during or just prior 

to the fall nectar flow when chemical treatments are proscribed by label restrictions. By the time the flow is over, 

mite populations have increased dramatically and colonies 

have suffered severe damage. The result is a loss of colonies during the fall flow or shortly thereafter. This phenomenon is known as ‚fall collapse,‛ although it may occur 

in late summer, winter or whenever mite populations are 

allowed to increase to high levels.

Often, infected colonies look strong after the fall flow, and 

the application of an effective pesticide kills most of the 

mites present; however, the colony still collapses and dies 

over the next few weeks or months. Such colonies experienced significant, but less obvious damage while waiting 

for the fall treatment. The lesson is simple. One cannot 

assume that a colony will survive the winter if one waits 

until the end of the fall flow to apply a pesticide. Mite levels must be kept low during the summer in order that colonies can rear healthy workers during late summer and 

early fall. 

IPM Chemical Control Methods 

Available Products

Currently, there are three products with Section 3 

(General Use) registration available for controlling V. destructor. These are Apistan®

(fluvalinate), Mite-Away IITM 

(formic acid) and SucrocideTM (sucrose octonaote esters). 

In addition, CheckMite+®(coumaphos) and Api-Life 

VAR®(thymol, menthol and eucalyptus oil) have been 

granted Emergency Exemptions from registration (Section 

18) by the US-EPA. These latter two products are only 

available in those states that have applied for and received 

Emergency Exemptions, which must be renewed each 

year. 

Pesticide Resistance

Resistance to the two major pesticides, Apistan®and 

CheckMite+®, is widespread. This is problematic because 

the resistance status of the mite population must be determined before treating a colony, rather than after. Presently, such a determination is difficult to obtain. See 

http://www.masterbeekeeper.org/ or to http://

www.ba.ars.usda.gov/beelab/ for information on making 

this determination. There is no known resistance to formic 

acid (Mite-Away IITM) at this time.

Established pesticide tolerances

Honey may contain 0.05 ppm fluvalinate and 0.1 ppm coumaphos. Beeswax may contain 100 ppm coumaphos. Remember! These are limits, not goals. Always think of pesticides as a means of last resort. Formic acid and sucrose 

octanoate esters are exempt from tolerance when used in 

accordance with label instructions. Menthol, thymol and 

eucalyptus oil (the active ingredients in Api-Life VAR®) 

are also exempt from tolerance, but their exempt status is 

subject to periodic renewal. 

How to minimize pesticide residues in hive 

products

The use of pesticides inevitably results in residues in wax 

and honey. To minimize this problem, and to ensure that 

residues do not exceed established tolerances, use pesticides only when necessary and only in accordance with 

label instructions. Use separate hive bodies and combs for 

your brood chambers and honey supers and keep them 

separate. Never move combs from the brood nest into the 

honey supers. An easy way to keep these combs separate is 

to use deep hive bodies for brood chambers and mediums 

or shallows for honey supers. Apply pesticides in the 

brood chambers, never in the honey supers. These practices will greatly reduce the level of pesticide residues in 

the honey and the wax cappings. 

General recommendations for the use of 

pesticides

DO:

1. Read and follow the product label.

2. Follow all safety instructions, and wear all indicated 

personal protection equipment.

3. Apply the proper amount of pesticide in the manner 

specified on the label.

4. Remove the pesticide at the end of the specified treatment period.

5. Dispose of used pesticides in the manner specified on 

the label.

6. Follow any required withholding period. This is the 

minimum time that must elapse between removing a 

pesticide or antibiotic from a colony at the end of a legal 

treatment period and the addition of supers for honey 

production.

7. Place pesticide strips in such a manner that they will 

remain in contact with the bees when the cluster contracts. This is particularly important in the fall. 
Integrated Pest Management for Varroa Destructor SARE 7

DON’T:

1. Leave pesticides in your colonies over the 

winter. It is illegal. It also increases the 

amount of time your combs are in contact 

with a pesticide, thereby increasing the risk 

of residues in hive products. It may also increase the chance of the mite population developing resistance to the pesticide. 

2. Reuse products.

3. Use any chemical, pesticide or formulation 

of a chemical or pesticide to control V. destructor unless it is legal to do so in your 

state.

4. Use any pesticide in a manner inconsistent 

with its label.

IPM Non-Chemical Control Methods 

Drone brood removal

Research: Mites are found most often on drone brood 

where they produce about twice as many offspring as on 

worker brood. Therefore, by removing capped drone 

brood from an infected colony, you remove a disproportionately large number of mites without affecting the 

worker population, and you remove those mites with the 

highest fecundity. Research at Dyce Laboratory for 

Honey Bee Studies at Cornell University has shown that 

the periodic removal of drone brood from a colony allows 

a beekeeper to skip the usual spring treatment, keep mite 

levels low throughout the summer and prevent fall collapse 

(figure 1). It may also eliminate the need for a fall pesticide 

treatment. The only way to determine that is to estimate 

the pest density on a colony-by-colony basis after removing the fall honey crop.

Implementation: You will need four drone combs per 

colony to use this method. Drone foundation can be purchased from several supply houses. The foundation is 

wired into frames and drawn out by colonies. One piece 

plastic drone combs are also available. Use two deep hive 

bodies for brood chambers, and separate them from the 

honey supers with a queen excluder. Cull worker combs in 

the brood nest with more than 1 to2 square inches of drone 

cells (photo H). Remember! The goal is to get the colony 

to consolidate all of its drone production in the 

removable drone combs. 

Place two drone combs in the upper brood 

chamber, one or two combs in from each side. 

Visit your colony every 26 to 28 days, remove 

the drone combs (photo I) and replace them 

with the drone combs that you removed on the 

previous replacement date. Place the combs of 

capped drone brood in a freezer, and keep 

them there until you are ready for your next 

exchange. Allow frozen drone combs to come 

to ambient temperature before placing them 

back in a colony. Be sure to visit your bees at 

least every 28 days to exchange combs because 

you don't want too many drones actually 

emerging in your hive. If a drone comb becomes filled with honey, you will need to substitute an empty drone comb and extract the 

honey before reusing it. In the north, you can 

exchange combs up to six times a season using 

Photo H. Comb of capped drone brood being removed from colony.

Apiary

N DH CG

Mites / Bee 

Control 

Drone Comb Exchange

0.25

0.20

0.15

0.10

0.05

Figure 1. September mite-to-bee ratios in colonies with and without drone 

brood removal during the spring and summer in three apiaries. 

Site 1 Site 2 Site 3
Integrated Pest Management for Varroa Destructor SARE 8

a 28-day interval between exchanges. The more often you 

exchange combs, the more you will suppress the mite 

population. The drone brood removal method has no 

known deleterious effects on colonies, and honey production may be marginally increased. 

Screen bottom boards

Research: Many studies have shown that mites 

fall off of bees at relatively high rates, even when 

no chemical treatment is present. Many of these 

mites are still alive and manage to reacquire a host. 

It is commonly believed that mite populations can 

be suppressed if these fallen mites can be removed 

from the colony before they reacquire a host. The 

screen bottom board allows mites that fall from 

bees to fall out of the hive. Since they cannot reenter the hive, they cannot re-acquire a host and 

they cannot contribute to the growth of the mite 

population. 

Three years of research at Dyce Laboratory at Cornell University have shown that screen bottom 

boards have no effect on mite populations (figure 

2). The reason for this is unknown, but it may be 

because the fallen mites are sick or old and no 

longer able to reproduce. However, research on the 

efficacy of screen bottom boards is mixed. Two 

other studies have shown numerical benefits from 

screen bottom boards, but the advantages were not 

statistically significant. One study has demonstrated a small but statistically significant benefit. 

Screen bottom boards do not appear to damage 

colonies. If effective mite knockdown agents can be 

identified, screen bottom boards may play a more 

significant role in mite management. 

Mite-resistant stock

There are two stocks of mite-resistant bees available. One 

is descended from Russian queens imported to the U.S. 

The other is known as SMR stock (for suppressing mite 

reproduction) that was developed from bees already present in the U.S. Both are the result of work conducted at 

the USDA-ARS Honey Bee Breeding, Genetics and 

Physiology Lab in Baton Rouge, LA. Performance of 

commercially available variants of these stocks is mixed. 

However, stock improvement is ongoing, and you are 

strongly encouraged to try them.

Swarm prevention

A swarm from one of your colonies will establish a nest 

within foraging distance of its parent colony. Invariably, 

swarms will have some mites, and since they do not receive treatment to control the mites, they will eventually 

collapse and die. As they do, the colonies in your apiary 

will likely rob them and return to their nests with a large 

Photo I. A worker comb with excess drone cells. Such a 

comb is best culled and replaced with a comb of 95-100% 

worker cells.

B. 

2002 2003

Mites / Bee

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Solid Bottom Boards

Screen Bottom Boards

A. 

MP N SM w

Mites / Bee

0.0

0.1

0.2

0.3

0.4

Solid Bottom Boards

Screen Bottom Boards

Figure 2. September mite-to-bee ratios in colonies with and without 

screen bottom boards during the spring and summer. No significant 

differences were found.

Site 1 Site 2 Site 3 Site 4
Integrated Pest Management for Varroa Destructor SARE 9

number of mites. Attend your bees, especially in the 

spring, when swarming is likely, and take all necessary 

steps to prevent it. Remember! A colony that you allow to 

swarm not only has created a future threat to your bees; it 

also will not produce nearly as much honey as if it had not 

swarmed.

Isolation

One way to reduce the rate at which mite populations rebound after treatment is to keep apiaries isolated from each 

other. Increasing the distance between apiaries reduces the 

chance of re-infestation from nearby collapsing colonies. A 

separation of three miles will provide some protection, 

while a separation of five miles is better. Isolation is not 

practical where colony density is high, and isolation cannot 

guarantee that your bees will not be re-infested because 

there may be wild colonies in the area. However, this 

method should not be overlooked when selecting apiary 

sites. 

Treatment Regimes

Modified traditional program (without 

drone brood removal and without economic thresholds)

If you do not base your treatment decisions on an estimate 

of pest density, you will need to treat your colonies twice 

each year: once in the late winter or early spring and once 

near or immediately after the end of the goldenrod flow. 

However, even that may not be sufficient. Therefore, inspection for evidence of parasitic mite syndrome prior to 

the start of the fall flow is highly recommended, although 

it is not as effective as estimating pest density. 

Late winter or early spring: 

! Treat colonies with Mite-Away IITM, Apistan® or 

CheckMite+®. 

Late summer (about 2 weeks before start of 

goldenrod flow):

!Inspect colonies for symptoms of parasitic mite syndrome. Remove all marketable honey from colonies 

with symptoms and initiate treatment with Apistan® or 

CheckMite+®. Mite-Away IITM (formic acid) will not 

work well at this time due to the presence of large 

quantities of brood. Procrastination at this stage will 

result in the loss of your colony. 

! Provide treated colonies with empty supers for fall 

honey production. Honey produced while pesticides 

are present in the hive may not be used for human consumption. However, it may be used as feed for other 

colonies. This allows a beekeeper to remove both the 

surplus honey and the winter stores from healthy colonies that were not treated during the fall flow and to 

replace their winter stores with surplus honey from 

colonies that were treated. Using this method, you save 

the bees and harvest the same amount of honey.

Late summer - early fall (when the goldenrod 

flow is about 80% complete):

! Remove surplus honey.

! Reduce colony to two, full-depth hive bodies.

! Treat with an approved pesticide. Note! Mite-Away II®

should be applied after the majority of brood rearing 

has ended but while daytime temperatures range between 50 and 79 oF. In Ithaca, NY we initiate treatment 

with formic acid during the last week of September or 

first week of October, but not earlier and not later than 

that.

Basic IPM program (without drone brood 

removal but with economic thresholds): 

The best strategy for using a pesticide is to apply it only 

when the pest density reaches the economic threshold, that 

is, the level at which you must control the pest or expect to 

experience damage to your colonies. 

Late winter or early spring: 

! Treat colonies with Mite-Away II®, Apistan® or CheckMite+®

. 

Late summer (about 2 weeks before start of 

goldenrod flow):

!Estimate pest density in each colony with the ether roll. 

!If an ether roll count is less than or equal to three, or if 

you observe any symptoms of parasitic mite syndrome, 

remove all marketable honey from that colony and initiate treatment with Apistan® or CheckMite+®

. MiteAway II®

(formic acid) will not work well at this time 

due to the presence of large quantities of brood. Procrastination at this stage will result in the loss of your 

colony. 

! Provide treated colonies with empty supers for fall 

honey production. Honey produced while pesticides 

are present in the hive may not be used for human consumption. However, it may be used as feed for other 

colonies. This allows a beekeeper to remove both the 

surplus honey and the winter stores from healthy colonies that were not treated during the flow and to replace their winter stores with surplus honey from colonies that were treated. Using this method, you save the 

bees and harvest the same amount of honey.
Integrated Pest Management for Varroa Destructor SARE 10

Late summer - early fall (when the goldenrod 

flow is about 80% complete):

! Remove surplus honey.

! Reduce colony to two, full-depth hive bodies.

!Estimate pest density in each colony with the ether roll. 

!If an ether roll count is more than or equal to two, treat 

that colony with an approved pesticide. Note! MiteAway II®

should be applied after the majority of brood 

rearing has ended but while daytime temperatures 

range between 50 and 79 oF.. In Ithaca, NY we initiate 

treatment with formic acid during the last week of September or first week of October, but not earlier and not 

later than that.

Intensive IPM program (with drone 

brood removal, formic acid and 

economic thresholds)

The best strategy is to suppress mite populations during 

the summer with a non-chemical method, and then to treat 

with a natural product in the fall if the pest density exceeds the economic threshold. Drone brood removal can 

eliminate the need for a spring treatment and prevent fall 

collapse. Occasionally, it will result in the fall ether roll 

count being below the economic threshold level, eliminating the need for that treatment as well. Incorporating both 

drone brood removal and mite resistant stock into your 

management program may increase the number of colonies 

that do not require a fall treatment. At this time, it is recommended that you use a spring treatment if you did not 

use a treatment the preceding fall.

Late winter or early spring: 

! Make sure two empty drone combs are present in the 

upper brood chamber.

! No chemical treatment is necessary at this time if the 

colony was effectively treated with a miticide the previous fall.

Apple blossom until just before the end of the 

goldenrod flow:

! Use drone brood removal every 26 to 28 days with the 

last exchange taking place when surplus honey is removed just before the end of the goldenrod flow. If a 

drone comb becomes filled with honey, replace it with 

an empty comb and extract the honey before reusing it.

Late summer (about 2 weeks before start of 

goldenrod flow):

! Requeen with mite resistant stock and check for acceptance in seven days.

Late summer - early fall (when the goldenrod 

flow is about 80% complete):

! Remove surplus honey from colonies.

! Reduce colonies to two full depth hive bodies.

! Determine pest density in each colony with the ether 

roll.

!If an ether roll count is ≥ 2, treat that colony with MiteAway II® (photo J). Note! Mite-Away II®

should be 

applied after the majority of brood rearing has ended 

but while daytime temperatures range between 50 and 

79 oF. In Ithaca, NY we initiate treatment with formic 

acid during the last week of September or first week of 

October, but not earlier and not later than that.

!If you do not need to treat a colony in the fall, you 

should treat it the following spring.

Notes on treatment regimes

Be sure to determine if the mites in your colonies are resistant to Apistan® or CheckMite+® before applying either 

of those products. Always use the appropriate product. 

There is no known resistance to formic acid (Mite-Away 

II) at this time. 

SucrocideTM and Api-Life VAR® are not included in the 

treatment regimes at this time because there is insufficient 

data available on which to base such recommendations. 

Preliminary tests have found SucrocideTM to be ineffective 

in the northeast. It is also very labor intensive. Previous 

work with Api-Life VAR® was based on a single application and yielded highly variable results. Current label inPhoto J. A formic acid pad similar to the Mite-Away IITM pad.
Integrated Pest Management for Varroa Destructor SARE 11

structions call for three applications at seven- to 10-day 

intervals. This may prove more effective, but confirming 

studies have not been published. Treatment regimes will 

be updated as information becomes available.

The drone comb exchange method must be used as indicated above in the ‘Implementation’ section. NEVER leave 

drone combs in colonies unless you are going to exchange 

them at least every 28 days. 

Ether roll counts given above are 300-bee counts.

Other treatment regimes for V. destructor are constantly 

being evaluated by a number of researchers, and the number of available options is increasing rapidly. Check with 

your local extension apiculturist for the most recent updates before implementing any IPM program. 

Important terms 

drone and worker comb: wax comb built by bees for 

storing honey and pollen and for rearing drone (male) and 

worker (female) honey bees, respectively. The cells that 

make up drone comb are slightly larger than those that 

make up worker comb. 

larva: the feeding stage of an immature insect. 

pupa: the quiescent stage of an immature insect during 

which time it undergoes dramatic physiological and morphological changes as undergoes the transition from the 

larval stage to the adult stage. 

brood: the immature stages of the honey bee, including 

the egg, larval and pupal stages. Immature workers and 

drones develop in worker and drone cells, respectively. 

Queens are reared in special queen cells, which are seasonal and relatively few in number.

capped stage: the period when a cell containing an immature bee is capped with wax. A brood cell is capped 

from the late larval stage until the bee emerges from the 

cell as an adult.

hemolymph: insect blood.

pest density: the number of pests in a sample of known 

size. Mite density can be measured several ways. Some of 

these include the number of mites per adult bee, the number of mites per 300 adult bees, or the number of mites in a 

standard volume of adult bees.

economic injury level (EIL): the lowest pest density 

that causes economic damage.

economic threshold level (ETL): the pest density 

that triggers an action designed to prevent the pest population from reaching the economic injury level. The ETL is 

always less thanor equal to the EIL.

pesticide: includes many kinds of ingredients used in 

products, such as insecticides, miticides, fungicides, rodenticides, insect repellants, weed killers, antimicrobials, and 

swimming pool chemicals, which are designed to prevent, 

destroy, repel, or reduce pests of any sort.

pyrethroids: a class of synthetic pesticides with chemical structures similar to pyrethrum, a naturally-occurring 

substance in chrysanthemums with pesticidal activity. 

Generally, moderate to high doses of pyrethroids are necessary to cause acute toxicity in mammals. Apistan®

(fluvalinate) is a pyrethroid used for controlling V. destructor. 

organophosphates (OP’s): a class of synthetic pesticides containing phosphorous. Generally, very low doses 

of OP’s can cause acute toxicity in mammals. OP’s can also 

cause cumulative, irreversible nerve damage at sub-lethal 

doses. CheckMite+®(coumaphos) is an OP registered for 

control of V. destructor in some states.

organic acids: a group of carbon-bearing acids, including acetic, formic, lactic and oxalic acids. Organic acids can 

cause severe burns to the skin, eyes and respiratory system. Mite-Away IITM is a formulation of formic acid registered in the US for control of V. destructor.

essential oil: the volatile and aromatic liquid or semisolid obtained from a single botanical species, primarily 

through a distillation, expression or extraction process. Essential oils are blends of many compounds, the various 

compounds being natural products, many of which act as 

antibiotics and/or pesticides. One such compound, thymol, 

is derived from thyme oil and is the primary active ingredient in Api-Life VARTM, a product registered for control 

of V. destructor in some states.

tolerance: the maximum residue limit, which is the 

amount of pesticide residue allowed to remain in or on a 

treated food commodity. If residues exceed the tolerance 

level, the commodity is subject to seizure and destruction. 
Integrated Pest Management for Varroa Destructor SARE 12

Some pesticides are exempt from tolerance (e.g. formic 

acid), while others have a time-limited exemption that 

must be periodically renewed (e.g. thymol, menthol and 

eucalyptus oil). 

off-label use: the use of any registered pesticide in a 

manner inconsistent with its label. 

Integrated Pest Management (IPM): a pest management program based on the coordinated use of multiple 

tactics (including biological, cultural, genetic, mechanical 

and chemical) and environmental data (pest densities, economic thresholds) and designed to maintain pest populations below the economic injury level with the least disruption to the environment. 

SARE Research Synopsis

Research on the efficacy of drone brood removal for the 

management of V. destructor in colonies of the honey bee 

A. mellifera L. was funded by Northeast SARE, USDA 

and the Organic Farming Research Foundation (Santa 

Cruz, CA). Experimental colonies were treated with 

CheckMite+ in the fall. The following spring, quantities of 

bees and brood were equalized, but colonies were not retreated. The brood nest of each colony consisted of 18 fulldepth worker combs and 2 full-depth drone combs housed 

in two, 10-frame hive bodies. Each worker comb had < 

12.9 cm2 of drone cells. Drone combs were kept in the second and ninth positions of the upper brood chamber. 

Standard management practices were used throughout the 

season, including the addition of honey supers above a 

queen excluder. Colonies were randomly assigned to one 

of two groups. In the control group, drone combs remained in place throughout the season. In the treatment 

group, drone combs were removed on June 16, July 16, 

August 16 and September 16 and replaced with empty 

drone combs (16 June) or with drone combs removed on 

the previous replacement date. In the early fall, the average mite-to-bee ratio was significantly greater in the control group than in the treatment group (figure 1).

Drone brood removal did not adversely affect colony 

health as measured by the size of the worker population or 

by honey production. Fall worker populations were similar 

in the two groups. Honey production in treatment colonies 

was greater than or similar to production in control colonies. These data demonstrate that drone brood removal 

can serve as a valuable component in an IPM program for 

V. destructor and may eliminate the need for other treatments on a colony-by-colony basis.

Research on the efficacy of screen bottom boards for the 

management of V. destructor in colonies of the honey bee 

A. mellifera L. was funded by Northeast SARE, USDA 

and the Organic Farming Research Foundation (Santa 

Cruz, CA). The study extended over three years. 

In the first year, 64 colonies were randomly assigned to 

one of two groups: a treatment group in which colonies 

received screen bottom boards and control group in which 

colonies received regular, solid bottom boards. Equal numbers of colonies from both groups were randomly assigned 

to four apiary sites for evaluation. In both the second and 

third year, 32 colonies were randomly assigned to one of 

two treatment groups, but colonies were kept in a single 

apiary each year. Mite-to-bee ratios were estimated in the 

early fall each year. 

The average mite-to-bee ratio in the treatment group was 

not significantly greater than the corresponding ratio in 

the control group in any year (figure 2). Screen bottom 

boards did not adversely affect colony health as measured 

by the size of the worker population or by honey production. Fall worker populations were similar in the two 

groups. Similarly, seasonal honey production was similar 

in the two groups. These data demonstrate that screen bottom boards do not provide any benefit as a mite control 

tactic during the honey producing season. 

This fact sheet is based on a SARE-funded project. 

For more information, please visit www.sare.org > 

Project Reports > ‘Search the Database’ 

for project #LNE00-130
Integrated Pest Management for Varroa Destructor SARE 13

References

Calderone N. W. and Turcotte R. 1998. Development of sampling methods for estimating infestation levels 

of Varroa jacobsoni (Acari: Varroidae) in colonies of the honey bee, Apis mellifera (Hymenoptera: Apidae) J. 

Econ. Entomol. 91: 851-863.

SARE Fact Sheet #02AGI2005