Bumble Bees of Alaska: A Field Guide

Introduction to Bees of Alaska

By Jessica Rykken, Entomologist

Bumble bees are abundant and conspicuous pollinators across most of Alaska. They are well-adapted to cold, harsh climates and live in every habitat where there are fowers offering up pollen and nectar, including forests, shrublands, tundra, wetlands, riparian areas, beaches, and gardens. Some species are generalists, distributed widely across habitats and regions, while others are restricted to particular habitats or known only from certain areas. Bumble bees are pollinators of many Alaskan wildfowers, as well as shrubs like willows, blueberries, and cranberries. Many animals, including humans, rely on these pollinated plants for food, shelter, and medicine. Thus, bumble bees, as well as many other kinds of bees and insect pollinators, are essential members of Alaskan ecosystems.

The details of this natural history guide are laid out below, or you can download a print-friendly version of the bumble bee identification guide.

Using This Guide

The guide covers all 22 bumble bee species known in Alaska. Read the following sections to familiarize yourself with bee anatomy and what to look for when trying to identify a bumble bee. Note that the guide is for female bees only (workers or cuckoo females). Use the distribution information to get an idea of which species are known from the area you’re in. Bees are easiest to identify when they are foraging. Position yourself near an active patch of fowers—blue, pink, or purple are often favored by bumble bees—and spend some time observing. Close-focus binoculars can be helpful. Taking a photo that you can refer to later is also a good way to practice. You can submit photos to online groups like iNaturalist or BugGuide for more help.

Look for distinctive patterns when identifying bees. Left: The cryptic bumble bee has a white “tail.” Middle: Cuckoo bees have shiny abdomens. Right: The forest bumble bee is one of several species with a wide orange belt. Photo credits from left to right: Scott King; Liz Osborn; Matt Muir

Is It a Bumble Bee? Mimics

There are a surprising number of insects that mimic bumble bees to fool predators into thinking they can sting. Many of these bee impostors also forage at fowers. Here are some common bumble bee look-alikes:

Left: The caribou warble fly (Hypoderma tarandi) looks like a bumble bee but lacks mouthparts as an adult.

Middle: This orange-legged drone fly (Eristalis flavipes) is another excellent mimic, but note the large eyes, single pair of wings, and tiny bristly antennae that identify it as a fly.

Right: Even moths can mimic bumble bees! The furry body and colored bands of this hummingbird clearwing moth (Thysbe hemaris) can fool a predator. Photo credits from left to right: John Melkle; Paul Tavares; Robert Brown

Bumble Bee Anatomy

Like most insects, bumble bees have 3 main body sections, 3 pairs of legs, and 2 pairs of wings. Bumble bees are larger than most other bees and much of their body is covered in long, colorful hair. Most female bumble bees have a concave pollen basket on each hind tibia for carrying loads of pollen and nectar back to the nest; these yellow or orange pollen balls are often visible.

Anatomy of a bee. NPS Illustration / Laurel Mundy

Tips for Identifcation

Many bumble bees can be identifed to species based on hair color alone. Check the color on the face, top and sides of thorax, and six abdominal tergites (T1–T6). Some species show a lot of color variation regionally, see notes for each species. Bees may also lose hair as the season goes on, making them look darker. Besides hair color, features like cheek length or the texture of the exoskeleton can be important for identifcation, but these require careful examination under magnifcation.

Bombus flavifrons NPS Illustration / Laurel Mundy

Males, Workers, and Queens

The anatomy of male and female bumble bees differs (see below). Males are typically produced later in the season, when new queens also appear. Once males leave the nest they don’t return, and can be found congregating with other males on flowers at night or in bad weather. Queens are generally very similar in appearance to workers (sterile females) but have a larger body size.

Male features:

• Longer antennae
• Hairier head
• Hair patch on mandibles
• No pollen baskets
• 7th abdominal segment
• No stinger

Bombus flavifrons. A worker bee (left) and queen bee (right). NPS Illustration / Laurel Mundy

NPS Illustration / Laurel Mundy

Bumble Bee Cheeks

There are several species that can be told apart reliably only by looking at the length of their cheeks. This is the distance from the bottom of the eye to the “hinge” of the mandible.

The cheek is hard to see with the naked eye but we have included its length in the species descriptions.

• Short: Length < Width
• Medium: Length = Width
• Long: Length > Width

Bumble Bee Distribution and Status

The table below provides information on the known distribution, habitat associations, and status of each bumble bee species across Alaska. Note that there are still a lot of information gaps, especially in more remote areas of the state, so you may make new discoveries. Ecoregion key is below the distrubition and status table.

Alaska Ecoregion Key

Alaska Ecoregion Map

Ecoregion map of Alaska for use in identifying bumble bee distribution. NPS / Marty Byrne

Annual Life Cycle of Bumble Bees

Bumble bees are among the frst insects to be active in the spring, feeding on willows and other early-blooming plants (A, below). These emerging queens have spent the last 7 or more months underground. After building up her energy reserves, the queen will establish a nest in an abandoned burrow or underground cavity and begin to lay eggs (B). She produces her frst brood of workers (sterile females) and they will take over the work of foraging and raising the young (C). Later in the summer, the queen switches to producing males and fertile females (new queens), which will mate with bees from other colonies (D). When colder weather sets in, most of the colony members die. Only the newly-mated queens will overwinter (E).

The lifecycle of a social bumble bee NPS Illustration / Laurel Mundy

Alternative Lifestyles:Cuckoo Bumble Bees

A few bumble bee species in Alaska are parasitic on other bumble bees. A female “cuckoo” bee invades the nest of a social bumble bee, kills the queen and forces the workers to raise her young. Most cuckoo bees are fairly specifc about which species they parasitize. Because they never need to carry pollen, most female cuckoo bumble bees lack pollen baskets on their legs.

Conservation Status of Bumble Bees in Alaska

We still have a lot to learn about bumble bees in Alaska: how species are distributed across our vast landscapes and how their populations are faring. Some species of conservation concern in other parts of North America (e.g., the Western bumble bee and its parasite, the Ashton cuckoo bumble bee) appear to be fairly stable in Alaska.

Climate change is an accelerating threat for many plants and animals at northern latitudes, and bumble bees living in vulnerable habitats (e.g., tundra) are likely at risk. Inventory, monitoring, and conservation of bumble bee diversity will be essential to preserving the health of our wild and cultivated landscapes. You can help by learning more about bumble bees in places you live and visit.

Resources to Learn More

Bumble bees of North America. P. Williams, R. Thorp, L. Richardson, and S. Colla. 2014. University of Princeton Press.

• Update to the identifcation guide to female Alaskan bumble bees and a summary of recent changes to the Alaskan bumble bee fauna. D. Sikes and J. Rykken. 2020. Alaska Entomological Society Newsletter 13:31-38.
• Alaskan bumble bee conservation status reports

Where this belongs

• Alagnak Wild River
• Aleutian Islands World War II National Historic Area
• Aniakchak National Monument & Preserve
• Bering Land Bridge National Preserve
• Cape Krusenstern National Monument
• Denali National Park & Preserve

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