Are There Black Widows in Colorado?
Yes, black widows are present in Colorado, primarily in the southern portions of the state and at lower elevations. Colorado's cooler climate limits black widow populations compared to warmer states. Black widow bites are rare in Colorado. Most people never encounter one. Understanding their presence, prevention, and response will help you manage the very low risk they pose.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated July 22, 2026.
Northern Black Widow · Joseph McPhail CC BY
Western Black Widow · Rebecca Ray CC BY
Western Black Widow · Michael Eisen CC BY
- 1
- species recorded
- 1,743
- GBIF records
- September, August, October
- peak months
Yes, black widows are in Colorado. Next you'll want:
Real sighting data, source iNaturalist
1,949 verified observations on iNaturalist of black widow have been recorded in Colorado, most often in September, August, October.
When black widow are recorded in Colorado
Yes, black widows are present in Colorado, primarily in the southern portions of the state and at lower elevations. Colorado's cooler climate limits black widow populations compared to warmer states. Black widow bites are rare in Colorado. Most people never encounter one. Understanding their presence, prevention, and response will help you manage the very low risk they pose.
Are they in Colorado?
Black widows are present in Colorado, particularly in the southern portions of the state and at lower elevations. They are found in areas like the Western Slope region, the southern Front Range near Colorado Springs and Pueblo, and southwestern Colorado near the Utah and New Mexico borders. They prefer warm areas and avoid high elevations. The Denver metropolitan area and Front Range corridor have smaller populations than southern regions. Northern Colorado and high mountain elevations above 7,000 feet are largely unsuitable for black widows due to cooler temperatures. Colorado's elevation and climate limit black widow populations compared to warmer states. Encounters are uncommon in Colorado, and bites are rare. Most Colorado residents and visitors never encounter a black widow. Being aware of their presence in certain regions and taking basic precautions is effective. For detailed information, visit ourColorado wildlife guide.
How dangerous is it?
Black widow venom is neurotoxic and medically significant, but serious problems are rare. A bite causes immediate local pain at the bite site, typically followed by muscle aches and cramping within a few hours. Symptoms may include pain radiating through muscles, cramping in the abdomen or back, and in severe cases, difficulty swallowing or breathing. Most people experience mild to moderate symptoms that resolve within a day or two with appropriate medical care. Serious medical complications are extremely rare, especially in healthy adults. Children and elderly persons should receive medical attention as a precaution. The good news is that black widow bites respond well to medical treatment. Pain management and supportive care lead to complete recovery in virtually all cases. Deaths from black widow bites in the United States occur perhaps once every few years and are exceptional with modern medical care. Your real risk is very small, and in Colorado it is even smaller due to the lower population of black widows. For more on black widow in Colorado, see ourColorado black widow guide.
How to recognize one
Black widows are distinctive and unmistakable when you know their appearance. Adult female black widows are shiny and glossy black with a distinctive red hourglass shape on the underside of their abdomen. The hourglass is split into two red triangles. Females are typically 10 to 13 millimeters in body length and appear quite round or bulbous. Male black widows are smaller, often half the size, and may have red or white markings along the sides of their abdomen. Look for their distinctive shiny black coloring. They build irregular, messy webs rather than neat geometric patterns. In Colorado, these webs appear in protected locations like building corners, eaves, sheds, garage corners, and undisturbed areas. Look especially in warm, sheltered spots. If you find a glossy black spider with a red hourglass marking on the underside of the abdomen, it is definitely a black widow. OurColorado wildlifeguide provides more identification details.
What to do if you are bitten or stung
If you are bitten by a black widow, stay calm. Bites are painful but rarely cause life-threatening symptoms. First, wash the bite area with soap and water. Remove any rings or tight clothing from the bitten limb in case swelling occurs. Keep the bitten area immobilized and still. Apply a cold compress if available to reduce pain and swelling. Do not attempt field treatment such as cutting, sucking, or applying tourniquets. Seek medical care as soon as possible. A doctor can evaluate the bite and provide appropriate pain relief and other treatment if needed. This is general information, not medical advice; if you are bitten, call Poison Control at 1-800-222-1222, or 911 if symptoms are severe. Symptoms such as severe muscle cramping, difficulty breathing, or severe chest pain warrant immediate emergency care. Most bites are managed at a clinic or hospital with supportive care and pain management. Medical professionals in Colorado are trained to handle black widow bites. You can also browseColorado wildlife.
How to prevent encounters
Prevention in Colorado is straightforward and effective. Keep your yard and garden areas clear of unnecessary clutter. Remove wood piles, stacked items, and debris where spiders hide. Store items like firewood off the ground and away from your home. Wear long sleeves, pants, and gloves when moving wood or handling stored items. Always shake out clothing, shoes, towels, and blankets before putting them on, especially if they have been sitting unused in storage areas. Check dark corners, shelves, and storage areas before reaching in. When working in garages, sheds, or outbuildings, remain aware of your surroundings. Seal cracks and gaps around doors, windows, and foundation areas to reduce entry points. Keep outdoor lighting to a minimum in areas where you do not need it, as lights attract insects that spiders eat. Inspect items before bringing them indoors. If you find a black widow web, simply remove it with a broom or stick. These simple steps reduce the likelihood of encountering a black widow in Colorado.
Where in Colorado and when
Black widows are found in southern Colorado and at lower elevations. The Western Slope region, Colorado Springs area, Pueblo region, and southwestern Colorado around Mesa Verde and the San Juan Mountains region have established populations. The Denver metropolitan area has much smaller populations. Northern Colorado and high mountain areas above 7,000 to 8,000 feet are largely unsuitable due to cooler temperatures and shorter warm seasons. They are most active from late spring through early fall, with peak activity during summer months when temperatures are warmest. Colorado's cool climate limits their activity season compared to warmer states. As temperatures drop in fall, black widows become less active. They are less common outdoors during winter but may move into buildings seeking shelter and warmth. Indoors, black widows may be encountered year-round, though less frequently than in warmer regions. Being aware of black widow seasonality helps you manage your personal risk. For more information, visit ourColorado wildlife guide.
Harmless lookalikes
Many harmless spiders in Colorado are mistaken for black widows, and this is actually reassuring. If you see a dark or black spider in Colorado, it is far more likely to be a harmless species than a black widow. Wolf spiders are common in Colorado, are dark and hairy, and have hunting behavior that makes them look more aggressive, but they are completely harmless. Jumping spiders are black with large forward-facing eyes and active, bouncy movements. Cellar spiders have much longer, thinner legs and are harmless. Fishing spiders are large and dark but have different markings and prefer wet areas. Many other harmless black spider species live in Colorado. The key difference with black widows is the distinctive red hourglass marking on the underside of the abdomen. If a spider lacks that hourglass, it is not a black widow. Most spiders you encounter in Colorado are beneficial and eat household pests. If you find any spider without the hourglass marking, you can feel confident it is harmless.
Frequently Asked Questions
Q: Are black widows deadly in Colorado? A: Black widow bites are rarely deadly. Deaths are very uncommon in the United States, and most involve people who did not seek medical care. With prompt medical attention, recovery is nearly always complete. Colorado hospitals treat black widow bites routinely. Q: How common are black widow bites in Colorado? A: Bites are uncommon. Colorado's cooler climate limits black widow populations. In a state with over 5 million people, very few bites are reported each year. Most people never encounter a black widow in their lifetime. Q: What attracts black widows to Colorado homes? A: Black widows seek shelter, warmth, and places where insects congregate. They prefer dark, undisturbed areas. Reducing clutter and sealing entry points is the best prevention. Q: What should I do if I see one? A: Simply leave it alone and avoid the area. Black widows are not aggressive and will not bite unless handled. If you must remove one, use a broom to brush it away or call a local pest control service. Learn more through ourwildlife guide.
Plan your trip
Best time to see black widow in Colorado: September, August, October
See the month-by-month sighting calendar.
Plan your black widow sighting in Colorado
1,743 verified black widow records have been logged in Colorado, most recently in 2026. See the GBIF records.
Where to look in Colorado
- Bent's Old Fort National Historic Site · Wildlife Watching, Birdwatching · Find hotels
- Black Canyon Of The Gunnison National Park · Wildlife Watching, Birdwatching · Find hotels
- Colorado National Monument · Wildlife Watching · Find hotels
- Curecanti National Recreation Area · Wildlife Watching, Birdwatching · Find hotels
- Dinosaur National Monument · Wildlife Watching, Birdwatching · Find hotels
- Great Sand Dunes National Park & Preserve · Wildlife Watching, Birdwatching · Find hotels
Frequently asked questions
Are they in Colorado?+
Black widows are present in Colorado, particularly in the southern portions of the state and at lower elevations. They are found in areas like the Western Slope region, the southern Front Range near Colorado Springs and Pueblo, and southwestern Colorado near the Utah and New Mexico borders. They prefer warm areas and avoid high elevations. The Denver metropolitan area and Front Range corridor have smaller populations than southern regions. Northern Colorado and high mountain elevations above 7,000 feet are largely unsuitable for black widows due to cooler temperatures. Colorado's elevation and climate limit black widow populations compared to warmer states. Encounters are uncommon in Colorado, and bites are rare. Most Colorado residents and visitors never encounter a black widow. Being aware of their presence in certain regions and taking basic precautions is effective. For detailed information, visit ourColorado wildlife guide.
How dangerous is it?+
Black widow venom is neurotoxic and medically significant, but serious problems are rare. A bite causes immediate local pain at the bite site, typically followed by muscle aches and cramping within a few hours. Symptoms may include pain radiating through muscles, cramping in the abdomen or back, and in severe cases, difficulty swallowing or breathing. Most people experience mild to moderate symptoms that resolve within a day or two with appropriate medical care. Serious medical complications are extremely rare, especially in healthy adults. Children and elderly persons should receive medical attention as a precaution. The good news is that black widow bites respond well to medical treatment. Pain management and supportive care lead to complete recovery in virtually all cases. Deaths from black widow bites in the United States occur perhaps once every few years and are exceptional with modern medical care. Your real risk is very small, and in Colorado it is even smaller due to the lower population of black widows. For more on black widow in Colorado, see ourColorado black widow guide.
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