Insects and diseases pose two of the most serious threats to a tree’s health. By examining specific symptoms of insect or disease damage, you can make a reasonable diagnosis of the problem and select the proper treatment.

If you are uncertain about the type of insect or disease or do not know how to treat them, contact your local CSFS Field Office to conduct a home-site assessment of the trees on your property.

Insect & Disease Activity Map

Use the control arrows on the left to display the legend and available map layers.

Use the plus and minus controls to zoom in on an area. Hold and drag your mouse to scan the map.

Use the search box on the upper right of the map to enter in the name of a specific town, city or location.

Click on a color-highlighted area on the map to display more information.

Insect & Disease Activity by County

The following tables provide information from the 2019 Aerial Detection Survey Summary for the Rocky Mountain Region (R2) of the U.S. Forest Service.

2019 Mountain Pine Beetle Activity

State 2018 Acres Affected 2019 Acres Affected 1996-2018 Cumulative Acres Affected 1996-2019 Cumulative Acres Affected
Colorado 470 720 3,375,000 3,376,000
County2018 Acres Affected2019 Acres Affected1996-2018 Cumulative Acres Affected1996-2019 Cumulative Acres Affected
Adams0011
Alamosa00430430
Archuleta0016,00016,000
Boulder01140,000140,000
Chaffee32083,00083,000
Clear Creek0082,00082,000
Conejos004,8004,800
Costilla004,6004,600
Custer701036,00036,000
Delta0088
Dolores001,2001,200
Douglas7235,00035,000
Eagle01194,000194,000
El Paso11013,00013,000
Elbert00540540
Fremont3035,00035,000
Garfield0011,00011,000
Gilpin0056,00056,000
Grand00581,000581,000
Gunnison06304,3004,900
Hinsdale003,2003,200
Huerfano0026,00026,000
Jackson81364,000364,000
Jefferson140036,00036,000
La Plata0012,00012,000
Lake0111,00011,000
Larimer203809,000809,000
Las Animas0013,00013,000
Mesa006,1006,100
Mineral00840840
Moffat0016,00016,000
Montezuma00690690
Montrose003,5003,500
Ouray002,0002,000
Park401138,000138,000
Pitkin0022,00022,000
Pueblo0021,00021,000
Rio Blanco0044,00044,000
Rio Grande003,4003,400
Routt00345,000345,000
Saguache1804043,00043,000
San Miguel004,0004,000
Summit00143,000143,000
Teller119,9009,900

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2019 Spruce Beetle Activity

State 2018 Acres Affected 2019 Acres Affected 1996-2018 Cumulative Acres Affected 1996-2019 Cumulative Acres Affected
Colorado 178,000 89,000 1,841,000 1,866,000
County2018 Acres Affected2019 Acres Affected1996-2018 Cumulative Acres Affected1996-2019 Cumulative Acres Affected
Archuleta3,4004,50055,00057,000
Boulder1,4006206,1006,300
Chaffee7,5007,90035,00038,000
Clear Creek5801,0009101,400
Conejos19,0006,100104,000105,000
Costilla8,9001,90016,00016,000
Custer4,40062036,00036,000
Delta90034,00034,000
Dolores1,30040027,00027,000
Douglas70370370
Eagle046,3006,300
El Paso120280210470
Fremont4,8002,20022,00023,000
Garfield134,7004,700
Gilpin20100100
Grand17,0009,70070,00072,000
Gunnison20,0004,500140,000141,000
Hinsdale19,00013,000275,000276,000
Huerfano3,2001,70012,00013,000
Jackson2,8001,60094,00095,000
Jefferson710110120
La Plata13,0009,00041,00043,000
Lake00690690
Larimer18,0005,60092,00094,000
Las Animas62800800
Mesa12010051,00051,000
Mineral1,4001236,000236,000
Moffat00750750
Montezuma006,7006,700
Montrose270580650
Ouray8003,6003,600
Park8,70011,00013,00018,000
Pitkin4612,00012,000
Pueblo170203,3003,300
Rio Blanco003,8003,800
Rio Grande9,9008095,00095,000
Routt1708085,00085,000
Saguache4,4001,000217,000218,000
San Juan6,0006,20025,00028,000
San Miguel20075,2005,200
Summit111,6001,600
Teller1,6008402,0002,800

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2019 Douglas-fir Beetle Activity

State 2018 Acres Affected 2019 Acres Affected 1996-2018 Cumulative Acres Affected 1996-2019 Cumulative Acres Affected
Colorado 14,000 7,400 444,000 450
County2018 Acres Affected2019 Acres Affected1996-2018 Cumulative Acres Affected1996-2019 Cumulative Acres Affected
Alamosa101180180
Archuleta28045038,00039,000
Boulder13280280
Chaffee401103,2003,300
Clear Creek101,1001,100
Conejos10306,1006,100
Costilla300403,1003,100
Custer201606,8006,900
Delta30304,2004,200
Dolores1601405,4005,500
Douglas3032045,00045,000
Eagle1,50053012,00012,000
El Paso82305,5005,700
Elbert0011
Fremont3013016,00016,000
Garfield16050036,00036,000
Gilpin006060
Grand221,3001,300
Gunnison2,60070037,00037,000
Hinsdale1,80054016,00016,000
Huerfano110703,0003,100
Jackson00570570
Jefferson1062011,00011,000
La Plata2602018,00018,000
Lake00120120
Larimer112,5002,500
Las Animas50506,2006,200
Mesa40309,1009,100
Mineral80047013,00013,000
Moffat8101,0001,000
Montezuma80708,1008,100
Montrose20014010,00010,000
Ouray1908019,00019,000
Park70301,7001,800
Pitkin1,40053013,00013,000
Pueblo04504,3004,700
Rio Blanco201509,7009,900
Rio Grande3401309,8009,900
Routt3035,1005,100
Saguache2,70034042,00042,000
San Juan2002,0002,000
San Miguel68023017,00017,000
Summit010500510
Teller1091,8001,800

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2019 Western Balsam Bark Beetle Activity

State 2018 Acres Affected 2019 Acres Affected
Colorado 24,000 23,000
County2018 Acres Affected2019 Acres Affected
Archuleta03
Boulder1,400710
Chaffee40060
Clear Creek9601,400
Custer2030
Delta69
Dolores2080
Eagle9802,000
Fremont200
Garfield170550
Gilpin280930
Grand2,8002,700
Gunnison3,6001,400
Hinsdale5005
Jackson9401,200
Lake510360
Larimer2,6001,100
Las Animas700
Mesa20280
Mineral3304
Moffat4601,200
Montezuma6110
Montrose020
Ouray2010
Park410240
Pitkin6601,600
Rio Blanco1,900750
Rio Grande406
Routt2,5003,100
Saguache01
San Juan2009
San Miguel04
Summit2,7002,800

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2019 Western Spruce Budworm Activity

State 2018 Acres Affected 2019 Acres Affected
Colorado 131,000 147,000
County2018 Acres Affected2019 Acres Affected
Alamosa1,600110
Archuleta2020
Chaffee7,0002,500
Conejos2,6006,500
Costilla5,600920
Custer5,9004,600
Delta35
Dolores13,00013,000
Eagle07
El Paso1,300180
Fremont12,0006,700
Garfield4100
Grand20060
Gunnison11,00026,000
Hinsdale720740
Huerfano1,200840
Jefferson1500
La Plata401,800
Larimer4300
Las Animas710280
Mesa21050
Mineral8302,300
Montezuma5,1009,100
Montrose410670
Ouray2,100550
Park14,0006,300
Pitkin3400
Pueblo0490
Rio Blanco430180
Rio Grande220760
Routt1,000230
Saguache30,00046,000
San Juan901,800
San Miguel11,00014,000
Summit070
Teller2,200300

2019 Bark Beetle in Pondersoa

County2018 Acres Affected2019 Acres Affected
Dolores2700022000
La Plata2060
Montezuma7030
Montrose207
San Miguel250310

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Individual Insect Activity

Roundheaded Pine Beetle

Roundheaded pine beetle activity has affected approximately 52 percent of the ponderosa pine forest ecosystems in Dolores County since 2000.

READ MORE

Spruce Bark Beetle

Severe outbreaks continued in portions of the San Juan Mountains, West Elk Mountains and Sawatch Range; the southern reaches of the Sangre de Cristo Mountains; and portions of north-central Colorado.

READ MORE

Douglas-fir Beetle

Widespread groupings of tree mortality occurred in portions of the northern Sawatch Range; northern areas of the La Garita Mountains, south of Gunnison; the Needle Mountains near Lake City; and the San Miguel River drainage.

READ MORE

Insects & Diseases in Colorado

Publications

More insect and disease publications

Forest Health Report

2019 Report on the Health of Colorado’s Forests

2019 Forest Health Report
New this year, the 2019 Report on the Health of Colorado’s Forests (3.5 MB PDF) digs into the four areas of our state with updates on insect and disease activity as well as an overview of the most common forest afflictions throughout the state.

The report also highlights forest management projects in each area that have helped Colorado mitigate wildfire, protect watersheds, turn beetle-killed stands into wood products, enhance wildlife habitat and more. Up-to-date photos, maps and charts in the report tell the complex story of how insects and diseases and on-the-ground projects are affecting Colorado’s forests.

2019 Report on the Health of Colorado's Forests (3.5 MB PDF)

Story Map

2019 Forest Health Report Story Map

CSFS Forest Entomologist Dr. Dan West has produced an Esri Story Map for the 2019 Forest Health Report, which tells the story of how data was collected to compile the report, and offers users an interactive way to find out about forest conditions in their area.

Use the plus and minus controls on the upper left of the map to zoom in or out on a specific area.

Click the magnifying glass icon to show the search box. Enter the name of a specific town, city or location to search.

Hold and drag your mouse to scan the map.

Click on a color-highlighted area on the map to display more information about insect activity.