Emerald ash borer now detected in more than 20 Front Range cities
First detected in Boulder in 2013, this invasive, tree-killing beetle threatens thousands of Colorado’s ash trees.
Common Forest Insects & Diseases
Alert: Mountain Pine Beetle Outbreak
We’re monitoring a mountain pine beetle outbreak on the Front Range of Colorado. Access key resources for managing mountain pine beetles in your trees and stay informed about the outbreak.
Common Forest Insects & Diseases
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.
Current Insect & Disease Activity in Colorado
Explore where insects and diseases are currently affecting forests in Colorado. This map shows data from an aerial survey conducted by the Colorado State Forest Service and U.S. Forest Service.
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 Mobile users may view a larger version of the map by visiting the Esri ArcGIS website. |
Forest Health Story Map
CSFS Forest Entomologist Dr. Dan West produces an Esri Story Map for the annual Forest Health Report. Explore the story map to learn how insect and disease data are collected during an annual aerial survey and find out more about forest conditions in your area.
Current Insect and Disease Activity by County and National Forest
Mountain Pine Beetle
Spruce Beetle
Douglas-fir Beetle
Western Balsam Bark Beetle
Western Spruce Budworm
Mountain Pine Beetle
| State Totals | 2023 Acres Affected | 2024 Acres Affected |
| Colorado | 3100 | 5300 |
| South Dakota | 330 | 340 |
| Wyoming-R2 | 550 | 630 |
| Colorado | 2023 Acres Affected | 2024 Acres Affected |
| Alamosa | 2 | 0 |
| Archuleta | 0 | 2 |
| Boulder | 20 | 90 |
| Chaffee | 130 | 80 |
| Clear Creek | 240 | 430 |
| Costilla | 0 | 80 |
| Custer | 10 | 10 |
| Delta | 2 | 0 |
| Dolores | 5 | 0 |
| Douglas | 8 | 50 |
| El Paso | 100 | 120 |
| Elbert | 30 | 8 |
| Fremont | 90 | 50 |
| Gilpin | 170 | 150 |
| Grand | 4 | 4 |
| Gunnison | 1100 | 2100 |
| Huerfano | 60 | 7 |
| Jefferson | 410 | 1200 |
| Larimer | 1 | 20 |
| Las Animas | 70 | 1 |
| Mesa | 140 | 210 |
| Mineral | 0 | 1 |
| Montrose | 250 | 130 |
| Ouray | 6 | 0 |
| Park | 180 | 480 |
| Pitkin | 3 | 30 |
| Rio Grande | 0 | 4 |
| Saguache | 50 | 0 |
| Teller | 50 | 90 |
| National Forest | 2023 Acres Affected | 2024 Acres Affected |
| Arapaho-Roosevelt | 90 | 230 |
| Bighorn | 100 | 210 |
| Black Hills | 650 | 400 |
| Grand Mesa-Uncompahgre-Gunnison | 1400 | 2100 |
| Medicine Bow-Routt | 6 | 6 |
| Pike-San Isabel | 430 | 920 |
| Rio Grande | 40 | 4 |
| San Juan | 5 | 2 |
| Shoshone | 10 | 8 |
| White River | 4 | 30 |
Spruce Beetle
| State Totals | 2023 Acres Affected | 2024 Acres Affected | 1996-2023 Cumulative Acres Affected | 1996-2024 Cumulative Acres Affected |
| Colorado | 19000 | 11000 | 1912000 | 1915000 |
| South Dakota | 0 | 0 | 130 | 130 |
| Wyoming – R2 | 2800 | 360 | 578000 | 578000 |
| Colorado | 2023 Acres Affected | 2024 Acres Affected | 1996-2023 Cumulative Acres Affected | 1996-2024 Cumulative Acres Affected |
| Alamosa | 0 | 0 | 3500 | 3500 |
| Archuleta | 370 | 20 | 58000 | 58000 |
| Boulder | 70 | 80 | 6700 | 6800 |
| Chaffee | 4400 | 1600 | 47000 | 47000 |
| Clear Creek | 30 | 20 | 2000 | 2000 |
| Conejos | 50 | 8 | 105000 | 105000 |
| Costilla | 890 | 290 | 19000 | 19000 |
| Custer | 230 | 210 | 39000 | 39000 |
| Delta | 70 | 20 | 35000 | 35000 |
| Dolores | 270 | 370 | 29000 | 29000 |
| Douglas | 0 | 0 | 360 | 360 |
| Eagle | 9 | 40 | 6500 | 6500 |
| El Paso | 20 | 5 | 540 | 550 |
| Fremont | 0 | 0 | 23000 | 23000 |
| Garfield | 40 | 7 | 4500 | 4600 |
| Gilpin | 0 | 10 | 100 | 110 |
| Grand | 1600 | 480 | 76000 | 76000 |
| Gunnison | 1400 | 2100 | 146000 | 147000 |
| Hinsdale | 1400 | 1500 | 277000 | 277000 |
| Huerfano | 250 | 140 | 16000 | 16000 |
| Jackson | 80 | 10 | 94000 | 94000 |
| Jefferson | 0 | 0 | 120 | 120 |
| La Plata | 2600 | 1400 | 47000 | 47000 |
| Lake | 10 | 10 | 840 | 850 |
| Larimer | 20 | 5 | 95000 | 95000 |
| Las Animas | 20 | 0 | 1100 | 1100 |
| Mesa | 520 | 230 | 51000 | 51000 |
| Mineral | 30 | 0 | 236000 | 236000 |
| Moffat | 0 | 0 | 730 | 730 |
| Montezuma | 110 | 40 | 6900 | 6900 |
| Montrose | 1 | 0 | 710 | 710 |
| Ouray | 40 | 50 | 4200 | 4300 |
| Park | 1100 | 880 | 22000 | 22000 |
| Pitkin | 8 | 280 | 13000 | 13000 |
| Pueblo | 70 | 80 | 4500 | 4500 |
| Rio Blanco | 0 | 0 | 3700 | 3700 |
| Rio Grande | 10 | 0 | 94000 | 94000 |
| Routt | 0 | 4 | 86000 | 86000 |
| Saguache | 0 | 0 | 218000 | 218000 |
| San Juan | 2900 | 900 | 30000 | 30000 |
| San Miguel | 610 | 110 | 6000 | 6000 |
| Summit | 0 | 1 | 1700 | 1700 |
| Teller | 90 | 0 | 3400 | 3400 |
| National Forest | 2023 Acres Affected | 2024 Acres Affected | 1996-2023 Cumulative Acres Affected | 1996-2024 Cumulative Acres Affected |
| Arapaho-Roosevelt | 270 | 140 | 91000 | 91000 |
| Bighorn | 170 | 70 | 24000 | 24000 |
| Black Hills | 0 | 0 | 130 | 130 |
| Grand Mesa-Uncompahgre-Gunnison | 3600 | 3700 | 358000 | 359000 |
| Medicine Bow-Routt | 680 | 300 | 315000 | 315000 |
| Pike-San Isabel | 6200 | 3000 | 148000 | 148000 |
| Rio Grande | 60 | 8 | 624000 | 624000 |
| San Juan | 5700 | 2600 | 269000 | 270000 |
| Shoshone | 2600 | 110 | 382000 | 382000 |
| White River | 100 | 340 | 32000 | 32000 |
Douglas-fir Beetle
| 2023 Acres Affected | 2024 Acres Affected | |
| Colorado | 17000 | 21000 |
| Wyoming-R2 | 350 | 130 |
| Colorado | 2023 Acres Affected | 2024 Acres Affected |
| Alamosa | 30 | 60 |
| Archuleta | 410 | 510 |
| Chaffee | 920 | 1000 |
| Clear Creek | 2 | 0 |
| Conejos | 90 | 120 |
| Costilla | 310 | 3000 |
| Custer | 620 | 640 |
| Delta | 40 | 30 |
| Dolores | 480 | 320 |
| Douglas | 1 | 10 |
| Eagle | 400 | 250 |
| El Paso | 20 | 160 |
| Fremont | 1100 | 1600 |
| Garfield | 290 | 200 |
| Grand | 6 | 90 |
| Gunnison | 3000 | 2000 |
| Hinsdale | 170 | 430 |
| Huerfano | 410 | 730 |
| Jefferson | 9 | 4 |
| La Plata | 1200 | 930 |
| Lake | 6 | 20 |
| Larimer | 300 | 20 |
| Las Animas | 90 | 220 |
| Mesa | 490 | 120 |
| Mineral | 930 | 890 |
| Moffat | 20 | 0 |
| Montezuma | 230 | 480 |
| Montrose | 490 | 260 |
| Ouray | 60 | 90 |
| Park | 50 | 130 |
| Pitkin | 550 | 310 |
| Pueblo | 20 | 40 |
| Rio Blanco | 170 | 130 |
| Rio Grande | 930 | 1100 |
| Routt | 60 | 20 |
| Saguache | 2900 | 4500 |
| San Juan | 50 | 100 |
| San Miguel | 370 | 590 |
| Summit | 20 | 60 |
| Teller | 4 | 150 |
| National Forest | 2023 Acres Affected | 2024 Acres Affected |
| Arapaho-Roosevelt | 310 | 80 |
| Bighorn | 20 | 3 |
| Grand Mesa-Uncompahgre-Gunnison | 2800 | 2300 |
| Medicine Bow-Routt | 50 | 9 |
| Pike-San Isabel | 2900 | 2600 |
| Rio Grande | 3700 | 5300 |
| San Juan | 2200 | 2300 |
| Shoshone | 300 | 90 |
| White River | 1200 | 770 |
Western Balsam Bark Beetle
| 2023 Acres Affected | 2024 Acres Affected | |
| Colorado | 27000 | 27000 |
| Wyoming-R2 | 4100 | 3400 |
| Colorado | 2023 Acres Affected | 2024 Acres Affected |
| Archuleta | 1 | 2 |
| Boulder | 290 | 90 |
| Chaffee | 40 | 90 |
| Clear Creek | 680 | 270 |
| Conejos | 0 | 50 |
| Costilla | 0 | 40 |
| Custer | 2 | 5 |
| Delta | 470 | 480 |
| Dolores | 780 | 800 |
| Eagle | 2400 | 2100 |
| Garfield | 1600 | 1200 |
| Gilpin | 50 | 40 |
| Grand | 1500 | 2400 |
| Gunnison | 1700 | 2500 |
| Hinsdale | 8 | 70 |
| Huerfano | 3 | 0 |
| Jackson | 1300 | 1200 |
| La Plata | 30 | 20 |
| Lake | 610 | 510 |
| Larimer | 530 | 740 |
| Las Animas | 10 | 0 |
| Mesa | 3800 | 2000 |
| Mineral | 40 | 120 |
| Moffat | 750 | 670 |
| Montezuma | 220 | 320 |
| Montrose | 120 | 20 |
| Ouray | 290 | 50 |
| Park | 70 | 70 |
| Pitkin | 850 | 1200 |
| Rio Blanco | 3400 | 2500 |
| Rio Grande | 1 | 10 |
| Routt | 4300 | 4600 |
| Saguache | 0 | 2 |
| San Juan | 60 | 90 |
| San Miguel | 420 | 1000 |
| Summit | 960 | 1400 |
| National Forests | 2023 Acres Affected | 2024 Acres Affected |
| Arapaho-Roosevelt | 2100 | 2000 |
| Bighorn | 150 | 90 |
| Grand Mesa-Uncompahgre-Gunnison | 5600 | 5400 |
| Medicine Bow-Routt | 5200 | 5100 |
| Pike-San Isabel | 730 | 630 |
| Rio Grande | 50 | 220 |
| San Juan | 990 | 1100 |
| Shoshone | 410 | 190 |
| White River | 6800 | 6800 |
Western Spruce Budworm
| 2023 Acres Affected | 2024 Acres Affected | |
| Colorado | 202000 | 217000 |
| Wyoming-R2 | 18000 | 17000 |
| Colorado | 2023 Acres Affected | 2024 Acres Affected |
| Archuleta | 8800 | 11000 |
| Chaffee | 8200 | 5600 |
| Conejos | 950 | 3000 |
| Costilla | 1700 | 2600 |
| Custer | 370 | 1300 |
| Delta | 18000 | 8500 |
| Dolores | 860 | 550 |
| Douglas | 0 | 180 |
| Eagle | 980 | 1000 |
| El Paso | 390 | 210 |
| Fremont | 3300 | 3200 |
| Garfield | 7100 | 1900 |
| Gilpin | 60 | 0 |
| Grand | 630 | 2800 |
| Gunnison | 45000 | 46000 |
| Hinsdale | 2900 | 6000 |
| Huerfano | 1100 | 3500 |
| Jackson | 460 | 2400 |
| Jefferson | 650 | 180 |
| La Plata | 4600 | 2900 |
| Lake | 930 | 940 |
| Larimer | 120 | 0 |
| Las Animas | 3900 | 5100 |
| Mesa | 18000 | 7500 |
| Mineral | 1000 | 6400 |
| Moffat | 1200 | 7700 |
| Montezuma | 1100 | 730 |
| Montrose | 5100 | 850 |
| Ouray | 1800 | 5500 |
| Park | 27000 | 26000 |
| Pitkin | 15000 | 4900 |
| Pueblo | 20 | 0 |
| Rio Blanco | 3600 | 2000 |
| Rio Grande | 290 | 1600 |
| Routt | 4700 | 22000 |
| Saguache | 9400 | 17000 |
| San Juan | 140 | 340 |
| San Miguel | 560 | 2800 |
| Summit | 350 | 580 |
| Teller | 1200 | 1400 |
| National Forest | 2023 Acres Affected | 2024 Acres Affected |
| Arapaho-Roosevelt | 190 | 50 |
| Bighorn | 760 | 3100 |
| Grand Mesa-Uncompahgre-Gunnison | 74000 | 68000 |
| Medicine Bow-Routt | 8300 | 36000 |
| Pike-San Isabel | 31000 | 30000 |
| Rio Grande | 4100 | 14000 |
| San Juan | 16000 | 16000 |
| Shoshone | 13000 | 6800 |
| White River | 29000 | 9000 |
Insects & Diseases News
Report: Outbreaks of forest pests spread during warm year
The annual forest health report assesses how insects are building populations in forests across the state and changing fuel dynamics for wildfire as they leave dead and dying trees in their wake.
Piñon Ips Bark Beetle Treatment Tips
The piñon Ips beetle (Ips confusus) poses a serious threat to piñon pine trees. Learn how to identify and treat these beetles in your trees.
Report: Forest Pests, Wildfire Concerns Persist Despite Milder Conditions in 2023
The annual forest health report details the current state of the health and condition of Colorado’s forests. Learn how the milder conditions in 2023 affected wildfire risk and forest pest activity.
Ask a Forester: Are Fading Evergreen Needles Normal in the Fall?
It’s common for evergreen trees in Colorado to show some fading yellow or brown needles in October. Learn the difference between the natural shedding process and an insect infestation.
Waugh-hoo Spruce Salvage Sale
Foresters from the CSFS and the Bureau of Land Management collaborated on a plan to reduce wildfire risk for Waugh Mountain in northwestern Fremont County.