United States 

Department o 

Agriculture 

Forest 

Service 

Northern 

Region 

200 East Broadway 

P.O. Box 7669 

Missoula, MT 59807 

Report 04-17 December 2004

A Summary of Verbenone Treatments on Lookout Pass Ski and Recreation Area, 2004

Carol Randall, Tom Eckberg, Gary Kempton, Doug Wulff, Lee Pederson of Forest Health Protection and 

John Wright, Coeur d’Alene River Ranger District 

Executive Summary 

The forests in and around Lookout Pass Ski and 

Recreation Area has a significant component of 

lodgepole pine susceptible to mountain pine 

beetle (MPB) (Dendroctonus ponderosae) 

attack. Aerial detection surveys (ADS) began to 

detect lodgepole pine mortality attributed to 

mountain pine beetle in the vicinity of the 

recreation area in the mid 1990’s. 

In 2003, to protect lodgepole pine in buffer strips 

between existing ski runs, the Idaho Panhandle 

National Forest’s (IPNF) treated 40 acres of 

buffer strips containing large diameter lodgepole 

pine with verbenone, the anti-aggregant 

pheromone for the mountain pine beetle. In 

2004, 100 acres were treated-on the wholetreated areas were protected. Some attacks 

were noted, particularly along the edges of 

treated and untreated polygons and in units 

treated for the first time in 2004, which had 2003 

attacks. 

Surveys conducted in the fall of 2004 in 

untreated areas show continued beetle activity 

in untreated polygons. In one untreated unit, the 

District is responding with a timber sale to 

remove currently infested and older dead trees. 

Prompt removal of currently infested trees 

should reduce beetle population pressure on 

adjacent units; however, will not eliminate the 

potential for additional mountain pine beetle 

attacks. 

To prevent mountain pine beetle mortality, an 

application of verbenone in high priority buffer 

strips in 2005 is advisable. Currently infested 

trees should be harvested prior to beetle flight 

(July) in 2005. In addition, managers might want 

to consider individual high-value tree protection, 

by using insecticidal sprays or for all trees in 

important buffer strips to protect against MPB 

and pine engraver (Ips Species) (IPS) attack 

(verbenone is not effective against IPS). Longterm solutions to bark beetle threat on Lookout 

Pass Ski and Recreation area should include 

development of a comprehensive vegetation 

management plan. 

Introduction 

Lookout Pass Ski and Recreation Area operates 

under a Forest Service special-use permit. 

Located on the border of the Idaho Panhandle 

and Lolo National Forests (LNF) the recreation 

area has provided winter recreation 

opportunities for over 67 years. The forests in 

and around the recreation area have a 

significant component of lodgepole pine 

susceptible to mountain pine beetle 

(Dendroctonus ponderosae). If mountain pine 
2 

beetles were to infest the forests of the ski hill, 

many of the larger diameter lodgepole pine trees 

in existing buffer strips between designated ski 

runs could be killed. 

In 2003, in order to protect the lodgepole pine in 

buffer strips, the IPNFs, which administers the 

ski hill’s special use permit, requested Forest 

Health Protection (FHP) funding to treat 40 

acres of buffer strips having large-diameter 

lodgepole pine with Verbenone, which is the 

anti-aggregant pheromone for mountain pine 

beetle. The Forest also conducted an extensive 

survey of buffer strips on the existing ski hill, and 

on buffer strips between new runs that were 

being created in the summer of 2003. There 

were no new mountain pine beetle attacked 

trees in the 2003 verbenone-treated areas on 

the ski hills. A detailed summary of 2003 

treatments and surveys on the ski hill can be 

found in, Randall, Carol. 2004. An Evaluation of 

Bark Beetle Conditions and Treatments on 

Lookout Pass Ski and Recreation Area, 2003

(R1-FHP-TR-04-04).

This report summarizes information on the 2004 

verbenone application, reapplication, and 

evaluation of treated and untreated units. It also 

discusses the 2005 FHP suppression request. 

2004 Treatment 

The Idaho Panhandle National Forests 

requested suppression funding to treat 100 

acres in the Lookout Pass Ski and Recreation 

Area with verbenone in 2004. Polygons were 

prioritized for treatment using the following 

criteria: percent BA lodgepole pine, location of 

the polygon on the ski hill, mountain pine beetle 

hazard rating, and average diameter of the 

lodgepole pine component. A map of the buffer 

strip polygons is in figure 1 and their priority for 

treatment is summarized in table 1. 

Based on the experience of other Forest Health 

Protection Specialists in Regions 1 and 4 

(Gibson, Munson, and Progar, Personal 

Communication, 2003), we applied 20, 5-gram 

verbenone pouches per acre on a 15-meter grid 

(~45’) to the treatment areas (polygons C, I&J, 

K, L, M, N, AA, BB, CC, DD, EE, FF, HH, & II) 

on May 2-3, 2004. We reapplied an additional 

20, 5-gram verbenone pouches per acre to the 

treatment areas on July 13-14, 2004. Refer to 

Appendix A for lot numbers of the verbenone 

pouches applied to treatment polygons. 

During the re-application process in July, crews 

looked for new mountain pine beetle attacks and 

found none.

Table 1: 2004 verbenone treatment priorities for buffer strip polygons between ski runs on Lookout Pass 

Ski and Recreation Area. (Refer to Figure 1 for polygon location). 

Polygon Acres Priority Polygon Acres Priority 

A & B 10 Not treated AA 3 1 

C 1.2 12 BB 4.7 6 

E 2.5 Not treated CC 4.3 7 

F 1.3 Not treated DD 6 8 

G 1 Not treated EE 25 10 

H 1 Not treated FF ~11 11 

I&J 5.5 13 GG ~9.5 Not treated 

K 1.1 2 HH 7 9 

L 2.5 3 II 2.5 14 

M 12.1 5 JJ & KK 25.7 Not treated 

N 14.1 4 

P 9.6 Not treated 
3 

Figure 1: Lookout Pass Ski and Recreation Area Ski Hill Schematic Spring 2003. Green polygons (A-P) 

represent buffer strips between established runs in the spring of 2003. Blue polygons (AA-KK) represent 

buffer strips between runs created through harvest in the summer of 2003. O represents an area 

surveyed but not treated in 2004. 

2004 Evaluation Methods 

In September, Carol Randall, Tom Eckberg, 

Gary Kempton, Doug Wulff, and Lee Pederson 

of Forest Health Protection were joined by John 

Wright, Coeur d’Alene River Ranger District to 

evaluate the treatment at Lookout Pass. Treated 

and untreated units were surveyed to determine 

if beetle activity was present on the ski hill. 

Surveys were conducted using defined Forest 

Insect and Disease Tally System (FINDITS) 

(Bentz 2000) methodologies. Based upon the 

size of the polygon, a number of basal area 

factor 20 variable radius plots were established 

a minimum of 130 meters apart and at least 60 

meters from the edge of surveyed polygons. In 

each variable radius plot, the species and d.b.h. 

of “in” trees was noted as was a FINDITS 

damage code (0= healthy tree, 1= unknown 

mortality, 2= current year mountain pine beetle 

(MPB) attack, 3= last year MPB attack, 4= older 

MBP attack, 5= unsuccessful MPB attack, 6= 

current strip attack, and 7= older strip attack). 

2004 Results and Discussion 

The number of variable radius plots, trees 

surveyed, and insect activity noted is 

summarized by polygon in Table 2. 

AA

A

C

B

E

D F

G

KK 

JJ 

II 

HH 

GG 

FF 

EE 

DD CC 

BB

P

O

N

H

L

M

I J 

K

 Recreation Area 

 Boundary 

 Existing Buffer 

 Strips 

 Buffer Strips 

 Created in 2003 
4 

Table 2: Number of 20 basal area factor (BAF) variable radius plots, total number of trees sampled, and 

number of trees attacked in 2004, 2003, and earlier for polygons surveyed on Lookout Pass Ski and 

Recreation Area Fall, 2004. 

POLYGON 

# BAF 20 

Plots 

# Trees 

Sampled 

# 2004 MPB 

Attacked 

Trees 

# 2003 MPB 

Attacked 

Trees 

# Older MPB 

Attacked 

Trees 

A 7 75 0 0 0 

D 2 19 0 0 0 

E 2 19 0 1 1 

F 2 24 0 0 1 

H 2 21 0 0 0 

I&J 6 64 3 0 0 

K 2 32 0 0 0 

L 3 52 1 0 0 

M 10 166 0 0 0 

N 10 97 4 (2 plots) 0 0 

O 10 99 16 (4 plots) 14 (4 plots) 5 (3 plots) 

P 7 43 11 (4 plots) 7 (2 plots) 0 

AA 3 33 0 0 0 

BB 4 51 0 0 0 

CC 4 45 0 0 0 

DD 5 66 0 0 0 

EE 10 123 0 1 4(2 plots) 

FF 5 56 1 5 (1 plot) 2 (2 plots) 

HH 7 77 4 3 (2 plots) 1 

II 2 21 0 0 0 

Survey data was entered into Excel 

spreadsheets then run through the Forest Insect 

and Disease Tally System (FINDITS) program. 

FINDITS survey results on 2004, 2003, and 

older mountain pine beetle attacks are 

summarized in Table 3.
5 

Table 3: FINDITS survey results for treated and untreated polygons on Lookout Pass Ski and 

Recreation area, 2004. Grey-shaded rows represent polygons with 2004 MPB attacks. 

Polygon 

2004 

Treatment 

2003 

Treatment 

2004 MPB 

Attacks 

TPA 

2003 MPB 

Attacks 

TPA 

Older MPB 

Attacks 

TPA 

A No Yes 0 0 11 

D No Yes 0 0 0 

E No Yes 0 7 18 

F No Yes 0 19 25 

H No Yes 0 0 0 

I&J Yes Yes 11 0 0 

K Yes Yes 0 0 0 

L Yes Yes 6 0 0 

M Yes Yes 0 0 0 

N Yes No 6 0 0 

O No No 29 43 21 

P No No 27 31 3 

AA Yes No 0 0 0 

BB Yes No 0 0 0 

CC Yes No 0 0 0 

DD Yes No 0 0 0 

EE Yes No 0 1 11 

FF Yes No 19 22 30 

HH Yes No 14 13 3 

II Yes No 0 0 0 

Survey results indicate that the majority of beetle 

activity is concentrated on the Montana portion 

of the ski hill. Polygons FF and HH were treated 

for the first time in 2004. Both of these polygons 

had mountain pine beetle activity in 2003 and 

earlier. Because there were beetles in these 

polygons at the time verbenone was applied in 

2004, we surmise that beetle pressure within the 

unit was stronger than verbenone’s ability to 

prevent attack. 

Treatment polygon N experienced 2004 beetle 

attacks. The attacks in this unit were 

concentrated along the border of polygon N and 

polygon O, an untreated unit. Polygon O 

experienced significant beetle attacks in 2003 

and 2004. It is likely that beetle pressure in 

polygon O was able to overpower the protection 

effect of verbenone along the treatment 

boundary. 

During the survey, we found one current (2004) 

attack in polygon L. 

The only other treated polygon to experience 

new 2004 mountain pine beetle attacks was 

Polygon I&J. Polygon I&J are adjacent to 

polygon P, which was not treated in 2003 or 

2004. In 2003, polygon P averaged 31 attacked 

trees per acre and in 2004 polygon P averaged 

27 attacked trees per acre. This represents a 

significant source of beetle population and, as in 

polygons N and O, we suspect the proximity of 

such beetle pressure to treated polygon I&J 

resulted in beetles overwhelming the treatment 

effect to a limited degree. 

An interesting finding is the lack of current beetle 

activity in polygons E and F. According to the 

2004 survey, both of these polygons had 2003 

mountain pine beetle attacked trees present 

within their boundaries. Survey efforts in 2003 

did not uncover this beetle activity. Neither unit 

was treated in 2004, however no new mountain 

pine beetle attacks were found. 
6 

Rate of Loss Predictions 

A 10-year rate of loss prediction model 

developed by Cole and McGregor (1983) was 

run on survey information collected in the fall of 

2004 from the buffer strip polygons. These 

results are summarized in Table 4. Cameron et 

al. (1990) found that in areas where mountain 

pine beetle populations became established, 

predictions of mortality using the Cole McGregor 

model were within 25% of the actual mortality 

observed. 

Table 4: Cole-McGregor (1983) mountain pine beetle in lodgepole pine 10-year rate of loss prediction 

model (if beetle populations become prevalent in a stand) results for leave strip polygons surveyed in 

2003 on the Lookout Pass Ski and Recreation Area. 

Additional Suppression Efforts

FINDITS survey results for polygon O showed 

unacceptably high mountain pine beetle 

mortality. Lookout Pass Ski and Recreation 

Area is in the process of a continued expansion 

and a timber sale to clear additional runs on the 

Idaho side of the mountain are planned for the 

summer of 2005. The District was able to 

incorporate salvage harvesting polygon O into 

the planned expansion. It is expected an 

estimated 50,000 board feet of beetle-killed 

lodgepole will be removed from polygon O prior 

to beetle flight in 2005. Similar efforts may be 

considered for polygons P, FF, and HH. 

Summary of Beetle Related Findings 

The lodgepole pine trees and forests in and 

around Lookout Pass Ski and Recreation Area 

are susceptible to bark beetle attack. Many of 

the buffer strips between ski runs on Lookout 

Polygon: Acres: 

Stand 

Hazard: 

PreOutbreak LP 

Pine TA 

Estimated 10-Yr 

Post Outbreak 

LP Pine TA 

Estimated % 

LP Pine TA 

Lost 

A 10.0 HIGH 267 98 63% 

D 1 HIGH 97 <1 99% 

E 2.5 MOD 233 45 81% 

F 1.3 MOD 206 31 85% 

H 0.8 MOD 115 32 73% 

I&J 5.5 MOD 186 26 86% 

K 1.1 LOW 478 24 95% 

L 2.5 LOW 712 129 81% 

M 12.1 HIGH 867 147 83% 

N 14.4 LOW 261 57 78% 

O 12 HIGH 172 96 44% 

P 9.6 MOD 82 59 28% 

AA 2.96 MOD 643 84 87% 

BB 4.69 HIGH 608 173 28% 

CC 4.25 HIGH 526 149 72% 

DD 5.96 HIGH 583 126 78% 

EE 25.03 HIGH 672 70 90% 

FF &GG20.48 HIGH 439 100 77% 

HH 6.94 MOD 281 67 76% 

II 2.52 HIGH 267 128 52% 

Highlighted rows represent polygons with current (2004) beetle activity. In most 

of the polygons on the ski hill, continued mountain pine beetle activity may result 

in significant losses to the lodgepole pine component. 
7 

Pass are comprised primarily or exclusively of 

lodgepole pine and would be substantially 

altered if beetle populations became established 

and lived up to their potential for tree killing 

(Table 3). Suppression efforts, including 

harvesting currently infested trees and area 

treatments with the anti-aggregation pheromone 

verbenone in 2004/2005, may prevent some 

MPB-caused lodgepole pine mortality in 2006. 

Surveys in untreated areas show that mountain 

pine beetle continues to kill trees in and around 

the ski hill. 

While the use of verbenone may have reduced 

MPB-caused mortality, it is not effective in 

preventing attacks by other bark beetles such as 

IPS. IPS, often associated with logging activity, 

was present and active on the ski hill prior to 

expansion related logging activities. Periodic 

inspections of slash piles created during logging 

activity during the summer of 2003 uncovered 

no large populations of IPS. Slash created 

during run-clearing operations was piled and 

burned in the fall of 2003, removing a potential 

source for IPS populations in 2004. Wind throw 

during the winter of 2003-2004 created a new 

potential food source for IPS beetles, but 

periodic surveys of this material conducted 

during 2004 verbenone application and posttreatment evaluation did not find evidence of 

increasing IPS populations. Planned harvests 

for additional ski runs in 2005 should be 

conducted in a way that will prevent IPS 

population build-ups. FHP will be happy to 

assist with these efforts. 

With the continued MPB and IPS activity in the 

vicinity of the ski hill, it will be necessary to 

continue to protect valuable susceptible 

lodgepole pine trees and stands. 

Recommendations 

o Many factors point to a potentially 

substantial and short-term reduction in 

the lodgepole pine component of the ski 

hill. While direct suppression efforts may 

increase the longevity of lodgepole pine, 

it would be prudent to consider what 

options are available to compensate for 

ongoing losses of this species. An 

evaluation of current conditions and 

threats to the vegetative component of 

the Lookout Pass Ski and Recreation 

Area would assist managers as they plan 

the future of the ski hill. 

o An application of verbenone in high 

priority buffer strips in 2005 is advisable. 

In addition, managers might want to 

consider individual tree protection using 

insecticidal sprays for certain high-value 

trees or for all trees in important buffer 

strips to protect against MPB and IPS 

attack (verbenone alone is not effective 

against IPS). 

o If possible, removal of currently infested 

lodgepole pine trees in polygons I&J, L, 

N, P, FF and HH should be considered 

along with the planned harvest in 

polygon O. 

o In the spring of 2005, green wind-thrown 

trees or slash should be removed from 

within and around the recreation area as 

soon as is practicable. If left on or near 

the ski hill, this material may act as a 

breeding ground for IPS beetles, 

resulting in additional losses of green 

trees or top kill. 

FY 2005 Suppression Request

The Idaho Panhandle National Forests 

requested funding to treat 120 acres in the 

Lookout Pass Ski and Recreation Area with 

verbenone in 2005. Polygons were prioritized 

for treatment using the following criteria: 

percent BA lodgepole pine, location of the 

polygon on the ski hill, mountain pine beetle 

hazard rating, and average diameter of the 

lodgepole pine component. Treatment polygons 

and their priority are summarized in Table 4. 
8 

Table 4: 2005 verbenone treatment priorities for buffer strip polygons between ski runs on Lookout Pass 

Ski and Recreation Area. (Refer to Figure 5 for polygon location). 

Literature Cited

Bentz, Barbara J. 2000. Forest Insect and 

Disease Tally System (FINDIT) User 

Manual. USDA Forest Service Rocky 

Mountain Research Station General 

Technical Report RMRS-GTR-49. April 

2000. 12 p. 

Cameron, D.E., A. R. Stage, N. L. Crookston. 

1990. Performance of three mountain pine 

beetle damage models compared to actual 

outbreak histories. USDA Forest Service 

Intermountain Forest and Range 

Experiment Station Research Paper INT435. 13 p. 

Cole, W.E., M.D. McGregor. 1983. Estimating 

the rate and amount of tree loss from 

mountain pine beetle infestations. USDA 

Forest Service Intermountain Forest and 

Range Experiment Station Research Paper 

INT 318. 22 p. 

Gibson, Ken. 2003. Personal Communication. 

USDA FS Region 1 Forest Health 

Protection Entomologist. Missoula, MT. 

Munson, Steve. 2003. Personal Communication. 

USDA FS Region 4 Forest Health 

Protection Entomologist. Ogden, UT. 

Progar, Robert. 2003. Personal Communication. 

USDA FS Region 4 Forest Health 

Protection Entomologist. Boise, ID. 

Polygon Acres Priority Polygon Acres Priority 

A & B 10 Not Treated AA 3 1 

C 1.2 12 BB 4.7 6 

E 2.5 Not Treated CC 4.3 7 

F 1.3 Not Treated DD 6 8 

G 1 Not Treated EE 25 10 

H 1 Not Treated FF ~11 11 

I&J 5.5 13 GG ~9.5 Not Treated 

K 1.1 2 HH 7 9 

L 2.5 3 II 2.5 14 

M 12.1 5 JJ & KK 25.7 Not Treated 

N 14.1 4 O 12 13 

P 9.6 Not Treated 
9 

Appendix A

Pherotech Inc. lot number of verbenone pouches used by treatment polygon and date applied. 

Lookout Verbenone Treatment Information: 

Block Acres 

Opt Dosage 

per 

application 5/2-3/04 Lots (#)* 7/13-14/04 Lots (#)* 

A 9.3 186 None None 

B 0.7 (1) 20 None None 

C 1.2 24 VP040427(24) VP040426(10) 

VP040427(14) 

D 1.0 20 None None 

E 2.5 50 None None 

F 1.3 26 None None 

G 0.9 (1) 20 None None 

H 0.8 (1) 20 None None 

I 4.7 94 VP040427 (94) VP0040427 (94) 

J 0.8 (1) 20 VP040427 (20) VP040427 (20) 

K 1.1 22 VP040427 (22) VP0040427(22) 

L 2.5 50 VP040427 (50) VP0040427 (50) 

M 12.1 242 VP040427 (242) VP040427 (5) 

VP040426 (194) 

VP040422 (43) 

N 14.1 282 VP040427 (282) VP040422 (48) 

VP040427 (234) 

P 9.6 192 None None 

AA 3 60 VP040427 (60) VP40427 (60) 

BB 4.7 94 VP040427 (94) VP040427 (94) 

CC 4.3 86 VP040427 (86) VP040427 (11) 

VP040428 (75) 

DD 6 120 VP040427 (120) VP040428 (120) 

EE 25 500 VP040427 (500) VP040427 (500) 

FF 11 220 VP040427 (220) VP040427 (220) 

GG 9.5 189 None None 

HH 7 140 VP040427 (44) 

VP040422 (96) 

VP040427 (140) 

II 2.5 50 VP040422 (146) VP 040427 (146) 

JJ&KK 25.7 514 None None 

*All verbenone lots had an extension of L1-2012/000 (Regular)