About Bees in Colorado

Honey Bees

Threat Level: 4/10

Honey bees are defensive only when protecting their hive. They won’t chase you or attack unprovoked. However, their massive colony size (up to 80,000 bees) means a disturbed hive can mount an overwhelming defensive response. The main concern is allergic reactions—honey bee stings can be fatal for sensitive individuals.

Everyone knows honey bees best because of the delicious honey their hives create. They flaunt a pale yellow and black medium-sized body, and like most bee species, hair covers their bodies to help collect pollen.

Size: ½ to ⅝ inch

Appearance: Pale yellow and black stripes, fuzzy body, large eyes

Colony size: 10,000 to 80,000 bees—massive compared to other species

Nesting: Build wax honeycomb inside enclosed cavities—tree hollows, wall voids, attics, chimneys.

Behavior: When they sting, their barbed stinger gets stuck in the victim’s skin, killing the bee—so they sting only as a last resort.

Lifecycle: Colonies are perennial—they survive winter by clustering together for warmth. A single queen can live 2-5 years.

Bumblebees

Threat Level: 2/10

Bumblebees are among the most docile bees you’ll encounter. Their large size and loud buzz make them easy to notice and avoid. They rarely sting unless directly handled or their ground nest is stepped on. Small colony size means even a disturbed nest poses minimal threat. Stings are painful but rarely cause severe reactions.

The gentle giants of the bee world—incredibly docile and common throughout Colorado during spring and summer. These fluffy giants amble from flower to flower collecting nectar and pollen.

Size: Over 1 inch—larger than most bees

Appearance: Large, very hairy bodies with rich black coloring, yellow and white stripes, short wings

Colony size: A few hundred residents—much smaller than honey bees

Nesting: Build nests close to the ground—under woodpiles, in compost heaps, or inside abandoned rodent tunnels.

Behavior: Females can sting multiple times without dying. Males don’t have stingers at all.

Lifecycle: Annual colonies. Only new queens survive winter by hibernating underground.

Carpenter Bees

Threat Level: 3/10 (Sting) | 6/10 (Property Damage)

Carpenter bees pose minimal sting risk—males are completely harmless (no stinger) despite aggressive-looking hovering behavior, and females rarely sting unless directly handled. However, they’re the only bee species that causes significant structural damage. Their tunneling weakens wood over time, and holes attract new bees year after year, compounding damage.

Carpenter bees look similar to bumblebees but have one key distinguishing feature: hairless, shiny black abdomens. They’re solitary—no colony to defend.

Size: Approximately 1 inch

Appearance: Yellow/black thorax like bumblebees, but with a distinctive shiny, hairless black abdomen

Nesting: Drill perfectly round holes (about ½ inch diameter) in wood to create “galleries” for eggs. Prefer unpainted, weathered wood.

Signs of infestation: Perfectly round holes in wood, sawdust beneath holes, yellow staining near entrances.

Mason Bees

Threat Level: 1/10

Mason bees are essentially harmless to humans. They’re solitary (no colony to defend), non-aggressive, and rarely sting even when handled. They don’t damage structures—they use existing holes rather than drilling new ones. These are bees you want around. Removal is almost never necessary.

Mason bees are solitary native bees famous for their efficient pollination and use of mud to construct nests. The term “busy bee” suits mason bees well.

Size: Slightly smaller than honey bees

Appearance: Dark coloring, often with metallic blue or green sheen, dense hair

Nesting: Lay eggs in existing holes—masonry cracks, nail holes, hollow stems. Seal cells with mud. Don’t drill holes like carpenter bees.

Behavior: Visit many different flowers per trip—making them incredibly efficient pollinators. A single mason bee can pollinate as much as 100 honey bees.

Lifecycle: Solitary. Adults emerge in spring, mate, lay eggs, and die by early summer.

Leafcutter Bees

Threat Level: 1/10

Leafcutter bees pose virtually no threat to humans. They’re solitary, docile, and focused entirely on leaves and flowers—not people. They can sting but almost never do. The only “damage” they cause is cosmetic—circular holes in leaves that don’t harm plant health. These beneficial pollinators are worth keeping around.

Leafcutter bees earn their name from their distinctive nest-building behavior: females cut small, circular pieces from leaves to construct nests.

Size: Similar to honey bees

Appearance: Dark colored, hairy underneath for carrying pollen

Nesting: Use leaf pieces to line nest tunnels in existing cavities—hollow stems, holes in wood, even rolled paper.

Signs: Distinctive circular holes cut in leaves—looks like someone used a hole punch on your plants.

Note: Removal is rarely necessary. These beneficial pollinators don’t damage structures.

Sweat Bees

Threat Level: 2/10

Sweat bees are tiny and mostly harmless. They land on people to drink sweat, which can be startling, but they only sting when trapped against skin. The sting is very mild—more of a pinch than real pain. They’re too small to pose any serious threat, and their pollination benefits far outweigh any minor annoyance.

Sweat bees are tiny—often overlooked until they land on you.

Size: Very small—about ¼ inch

Appearance: Often metallic green, bronze, or iridescent coloring. Some of the most beautiful bees in Colorado.

Nesting: Most species nest in the ground, creating small burrows.

Behavior: Attracted to the salt and moisture in human sweat—hence the name. They land on people to feed on perspiration.

Stinging: Can sting multiple times, but only when trapped or directly threatened. Very mild sting.

Note: Rarely require control unless populations are unusually high in a specific area.