1

Using MCH to Protect Trees and

Stands from Douglas-fir Beetle

Infestation

Forest Health

Technology Enterprise Team

TECHNOLOGY

TRANSFER Anti-aggregation

pheromone

Darrell W. Ross

Kenneth E. Gibson

Gary E. Daterman

Forest Health Technology Enterprise Team —

Morgantown, West Virginia

United States

Department of

Agriculture

Forest

Service

FHTET-2001-09

Revised March 2006
2

ACKNOWLEDGMENTS

The authors thank Tinathan Coger for editing and assisting with the layout of

this manuscript. The USDA Forest Service, Forest Health Technology

Enterprise Team, Morgantown, West Virginia provided funding for printing

this publication.

Cover Photo: Douglas-fir beetle caused tree mortality in northeastern 

Oregon.

Additional Copies

For additional copies of this publication, please contact Darrell W. Ross in

Corvallis, Oregon at (541) 737-6566 (E-mail: darrell.ross@oregonstate.edu),

Kenneth Gibson in Missoula, Montana at (406) 329-3278 

(e-mail: kgibson@fs.fed.us), or Richard Reardon in Morgantown, 

West Virginia at (304) 285-1566 (E-mail: rreardon@fs.fed.us).

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means for communication of program information (Braille, large

print, audiotape, etc.) should contact USDA’s TARGET Center at 

(202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of

Civil Rights, Room 326-W, Whitten Building, 1400 Independence

Avenue, SW, Washington, D.C. 20250-9410 or call (202) 720-5964

(voice and TDD). USDA is an equal opportunity provider and

employer.

The use of trade, firm, or corporation names in this publication is for the benefit

of the reader. Such use does not constitute an endorsement or approval of any

service or product by the U.S. Department of Agriculture to the exclusion of

others that may be suitable.
3

Using MCH to Protect Trees and Stands 

from Douglas-fir Beetle Infestation

Darrell W. Ross1, Kenneth E. Gibson2, and Gary E. Daterman (Retired)3

1 321 Richardson Hall 

Department of Forest Science 

Oregon State University

Corvallis, OR 97331-5752

2 U. S. Department of Agriculture

Forest Service

Forest Health Protection

200 E. Broadway

Missoula, MT 59807

3 U. S. Department of Agriculture

Forest Service

Pacific Northwest Research Station

3200 Jefferson Way

Corvallis, OR 97331
4
5

The Douglas-fir beetle (Fig. 1) is

normally present in forests at low

densities, breeding in Douglas-fir

trees that are injured or have recently

died. Tunneling by adults and larvae

beneath the bark produces a characteristic pattern distinguishing the

Douglas-fir beetle from other bark

beetles (Fig. 2). Beetle larvae need

fresh, moist phloem (inner bark) for

food, so trees that have been dead

for more than a year are not suitable

habitat. Injured or recently killed

trees have little or no defensive capabilities making them ideal sites for

beetle larvae to feed and develop.

Periodically, natural or humancaused disturbances such as windstorms, fire, defoliator outbreaks or

logging create an abundance of suitable breeding sites that

allow beetle populations to rapidly

increase to high densities. At high densities,

beetles are forced to

attack healthy, live

trees because there are

not enough stressed

and dead ones to support the population. By

attacking a live tree in

large numbers, the beetles are able to

overcome the tree’s natural defenses

and successfully reproduce. If an

attacked tree is not killed, then the

beetle’s eggs and larvae will not survive to the adult stage. Sometimes

only a portion of the tree is killed

and only the brood in that part of the

tree survive. This is commonly

referred to as a strip or partial attack.

Douglas-fir beetle outbreaks typically last for several years and may

result in the mortality of large numbers of trees. In some cases, this tree

mortality may interfere with

resource management objectives.

Douglas-fir beetles preferentially

attack large, old trees in dense stands

with a high Douglas-fir component.

In general, for areas east of the

Cascades in the Pacific Northwest

and the northern Rocky Mountains,

trees in stands with an average age

over 120 years and diameter at

breast height (dbh) of more than 14

inches are at the highest risk for

infestation during outbreaks. These

conditions are typical of late-successional or old-growth forests that are

becoming increasingly valuable for

recreational uses, watershed protection, wildlife habitat, and other reasons. Individual mature trees in resiFigure 1. Adult

Douglas-fir beetle

and eggs in gallery.

Actual size of the

adult is 4.5 - 7.0 mm

(about 3/16 - 1/4

inch) long. Photo

courtesy of Oregon

Department of

Forestry.

Introduction
6

dential settings may also be at highrisk for infestation when local beetle

populations are at high levels.

Mortality of large trees may reduce

the value of residential properties,

and such trees are often expensive to

remove when they are near homes or

other structures.

Until recently, resource managers

and homeowners had only one

option for protecting high-valued

trees from Douglas-fir beetle infestation during outbreaks. They could

spray a chemical insecticide on the

bole of the tree to kill arriving

insects. Effective insecticide applications require the entire lower and

middle portion of the bole be completely covered. This requires special

equipment that is not easily transported in the forest. Because of logistics and costs, only very high-value

trees in accessible areas could feasibly be treated with insecticides. In 

addition, concerns about non-target

effects of insecticides further limit

their application.

An alternative to insecticide applications became available for the first

time in spring 2000. This treatment

involves application of the Douglasfir beetle’s anti-aggregation

pheromone, MCH. (The chemical

names of all pheromones mentioned

in this paper are given in the appendix). This paper briefly describes

MCH and how to use the material to

protect live trees from infestation.

Bark beetles, including the

Douglas-fir beetle, rely on chemicals

known as pheromones to communicate with one another. Pheromones

are chemicals that are released by

one individual that affect the behavior of others of the same species. The

two most important types of bark

beetle pheromones are aggregation

and anti-aggregation pheromones.

As for all beetles in the genus

Dendroctonus, female Douglas-fir

beetles initiate new attacks. Upon

finding a suitable breeding site, the

female releases an aggregation

pheromone that is a blend of several

compounds including frontalin, seudenol, and MCOL that is attractive to

both male and female beetles.

Additional host tree odors may

enhance attraction to the pheromone.

As more beetles arrive and mate, the

concentration of aggregation

pheromone declines while the concentration of anti-aggregation

Figure 2.

Characteristic

pattern of

Douglas-fir

beetle egg and

larval tunnels.

Douglas-fir Beetle Pheromones

6
7

pheromone increases. The changes in

pheromone concentrations result

from females ceasing to release

aggregation pheromone while males

release the anti-aggregation

pheromone, MCH. The anti-aggregation pheromone serves to prevent

overcrowding and optimize brood

survival. In simple terms, MCH acts

as a "no vacancy" signal to late-arriving beetles, causing them to avoid

that tree or log. 

MCH was first isolated from

Douglas-fir beetles and identified in

1971. The ability of MCH to interrupt

the aggregation of Douglas-fir beetles was demonstrated in the early

1970’s. Subsequently, an operational

treatment for aerial application of

MCH to windthrown trees was

developed and demonstrated to be

highly effective. This treatment was

developed with the intent that it

could be used to prevent outbreaks

by keeping beetles from breeding in

trees killed or damaged during

windstorms. However, since this formulation of MCH was never registered with the Environmental

Protection Agency (EPA), it was

never available for widespread use.

In the early 1990’s, several studies

consistently demonstrated that MCH

could be used to prevent the infestation of live trees in high-risk stands.

These studies used MCH formulated

in individual releasers that were stapled to trees, snags, and shrubs

throughout areas to be protected. In

1999, the first EPA registration for a

bubble capsule formulation of MCH

was obtained for use in the U.S. Each

year since spring 2000, several thousand acres of high-value Douglas-fir

stands have been treated with MCH

throughout the western U.S. to prevent Douglas-fir beetle attacks. To

date, there have been no reports of

unsatisfactory results.

MCH Application

Where to Apply MCH

MCH applications should be prescribed in the context of a long-term

resource management plan. The

treatment is appropriate for any

stand where Douglas-fir beetlecaused tree mortality is expected to

be high enough to significantly

impact resource management objectives. In research and operational

tests, areas from less than one acre to

over 300 acres have been successfully treated. State or federal forest

entomologists or private forestry

consultants can help to assess the

risk of beetle infestation and the

potential value of an MCH application. Until recently, MCH sales were

limited to those with forest pest

management expertise, and knowledge of the product and its uses. This

policy was designed to prevent misuse of MCH and dissatisfaction that

might result. While MCH is now

available to the public from several

sources, consultation with pest management specialists is still recommended to ensure its proper use.

MCH effectively protects treated

stands by preventing beetles from

initiating new attacks. Beetles will

move through a treated area and

continue to disperse until they find

suitable habitat elsewhere or until
8

they die. Because beetles moving

through a treated stand will spend

more time searching for a host, they

presumably will have a greater

chance of dying as a result of longer

exposure to natural enemies and

other mortality factors. There is,

however, no evidence tree mortality

in areas directly adjacent to those

treated with MCH is any higher than

it would be in the absence of MCH

treatment. Consequently, landowners

and managers do not need to fear

that beetles will "move" from treated

stands into neighboring ones.

There is no conclusive evidence that

MCH applications alone will actually

reduce tree mortality at the landscape scale during an outbreak. At

the least, however, MCH acts to

redistribute tree mortality by protecting stands that are considered particularly valuable because of their

unique characteristics or special uses. 

How to Apply MCH

MCH is most effective when it is

applied before beetles begin to fly

and attack trees in the spring.

However, if it is applied early in the

flight season but after beetles have

initiated attacks on some trees, it

may still reduce the number of trees

that are killed within the treated area

as compared to doing nothing.

Throughout much of the interior

Pacific Northwest and northern

Rocky Mountains, Douglas-fir beetles begin flying in late April or early

May, so MCH applied by the third

week in April should be fully effective unless it is an unusually warm

year. The bubble capsule formulation

of MCH will last throughout the

period that beetles fly and attack

trees, but needs to be reapplied each

year that protection is desired.

During a typical outbreak, this may

require 1-3 annual applications. For

maximum benefit, protected areas

should be treated every year during

an outbreak. 

For areas greater than 1⁄2 acre, bubble capsules should be applied at a

rate of 30/acre. The current price of

bubble capsules is about $2.00 (U.S.)

each, but may be lower for large volume orders. If added insurance

against infestation is desired and cost

is not prohibitive, a slightly higher

rate may be applied. However, rates

higher than 30/acre should not be

necessary in most situations. The

first step in conducting a treatment is

to determine the size of area to be

treated and calculating the number

of bubble capsules needed.

Bubble capsules are applied by stapling or otherwise attaching them to

trees, snags, shrubs, fence posts or

any other object. They are usually

applied at a height that applicators

can easily reach (i.e., 6-8 feet), but

they can be placed higher in areas

such as campgrounds or residential

sites where it is likely that they may

be disturbed. Ladders or a special

long-handled hammer, known as a

Hundle hammer, can be used to

attach bubble capsules at a height

where they are beyond reach. If it is

necessary to achieve the proper spacing, they can also be attached to

objects such as stumps or logs as low

as 1-2 feet above the ground. Bubble

capsules are placed with the flat side

facing out and the bubble side

toward the object to which they are
9

attached (Fig. 3). They should be

attached on the north side of trees

and snags where possible to protect

them from direct sunlight, although

this is not critical for an effective

treatment.

MCH contained in a bubble capsule diffuses through the plastic and

is dispersed by air movement. In

essence, an invisible cloud of MCH

develops around the point at which

it is dispensed. The shape and distribution of the MCH cloud depends

upon the rate of diffusion, wind

speed, and wind direction. The

objective in area-wide treatment is to

place bubble capsules in a pattern

that results in a cloud of MCH sufficient to affect beetle behavior when

beetles are searching for host trees.

Several different patterns of placing MCH bubble capsules have been

used in research and operational

tests and they seem to be equally

effective. Since air movement disperses MCH as it diffuses out of the

bubble capsules, there is a lot of flexibility in the distribution of bubble

capsules provided the entire area is

covered. In the following descriptions, distances between bubble capsules are only approximate and pacing is accurate enough for effective

treatments. In all cases, bubble capsules should be placed about 30 feet

beyond the boundary of the area to

be protected to avoid an edge effect.

If this is not possible, placing bubble

capsules closer together along the

unit boundary will also help to prevent any untreated spots. For areas

less than about 2 acres, the best

approach is to place the bubble capsules evenly around the perimeter of

the unit. Spacing them about 15 feet

apart will result in a dose close to

30/acre. 

For larger areas, bubble capsules

can be placed around the perimeter

and in parallel lines across the unit

spacing them about 15-20 feet apart

(Fig. 4). The number of parallel lines

and spacing between them will

depend upon the size and shape of

the unit. The lines of bubble capsules will need to be spaced about

115-165 feet apart to achieve the

desired dose. If possible, these lines

should be placed perpendicular to

the expected wind direction on

warm afternoons in the spring when

beetles are most likely to be dispersing. After treating the perimeter and

determining the number of parallel

lines that will be needed to cover the

unit, the remaining bubble capsules

from the predetermined number

needed to treat the unit should be

divided into a number of lots equal

to the number of parallel lines. This

will help to ensure that the bubble

capsules are evenly spaced across

the unit. An alternative is to place Figure 3. MCH bubble capsule stapled to a tree.
10

the bubble capsules in an

even grid pattern across

the area (Fig. 5). Spacing

the bubble capsules 40

feet apart in the grid will

result in the desired dose.

Using the grid pattern

may require a little more

time since more of the

unit must be covered by

applicators. However, this

pattern may be easier for

the applicators to follow

and result in better coverage, particularly on large

areas. Either pattern of

deploying the bubble capsules will provide an

effective treatment provided the unit is evenly

covered. If bubble capsules are left over from

the predetermined number needed to treat a

given size unit, they

should be evenly distributed throughout the unit

or placed in areas with a

particularly high concentration of host trees.

For all areas less than 1⁄2

acre, a minimum of 16 bubble capsules should be evenly placed around

the unit boundary. Although this is a

higher dose than recommended for

larger units, it is necessary to ensure

complete coverage of small areas.

Individual-tree tests and operational use since 2001 have consistently shown 2 bubble capsules per tree

placed on opposite sides of the tree

will protect all but the largest susceptible Douglas-fir. For trees larger than

24 inches dbh, we suggest 4 bubble

capsules per tree placed equidistantly

around the bole. Height of placement

is not critical; however, it may be

preferable to place them out of reach

(10-12 feet from the ground) in recreational areas.

If bubble capsules are left in place

after treatment, they will eventually

fall to the ground and become less

noticeable as they break apart over

time. However, if this is unacceptable,

they can be collected and disposed of

after the beetle flight period has

ended. Bubble capsules should not be

collected before September.

Figure 4. Diagram of the perimeter and parallel line method of deploying

MCH bubble capsules. Bubble capsules are spaced about 15 feet apart

and lines are spaced 115-165 feet apart. Not drawn to scale.

Figure 5. Diagram of the grid method of deploying MCH bubble capsules.

Bubble capsules are spaced about 40 feet apart. Not drawn to scale.

30 foot wide buffer Bubble capsule

30 foot wide buffer Bubble capsule
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Checklist for Prescribing

and Applying MCH

● Seek guidance from a forest 

health management specialist

● Determine if the stand is at high 

risk for Douglas-fir beetle infestation

• Does the stand have a significant component of large, old 

Douglas-fir trees?

• Has the Douglas-fir beetle been 

causing mortality in the stand or 

adjacent stands in recent years? 

• Has there been a disturbance 

such as a windstorm that killed 

or weakened Douglas-fir trees 

in the stand or adjacent stands 

in the last 2 years?

● Develop MCH prescription 

consistent with an integrated 

resource management plan

● Determine size of the treatment 

area

● Determine number of bubble 

capsules needed to treat the area

● Order bubble capsules and store 

in a freezer, refrigerator or cold 

room whenever possible

● If necessary, flag treatment area 

boundaries and lines through 

the unit to facilitate the

application

● Avoid prolonged exposure to 

bubble capsule fumes during 

transport and application

● Wear gloves when handling 

bubble capsules

● Apply bubble capsules at 

30/acre before the third week 

in April in the interior Pacific 

Northwest and northern Rocky 

Mountains

● Attach bubble capsules at a 

height of 6-8 feet on the north 

side of objects with the flat side 

facing out

● In high use areas, attach the 

bubble capsules at a height that 

is out of reach

● If desired, collect bubble capsules no earlier than September

● Evaluate treatment effects one 

year after the application

● Retreat the area each year that 

Douglas-fir beetle infestation 

is likely

Appendix

Pheromone Names

(Common name/Chemical name)

Frontalin

1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane

Seudenol

3-methylcyclohex-2-en-1-ol

MCOL

1-methylcyclohex-2-en-1-ol

MCH

3-methylcyclohex-2-en-1-one
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