Bumblebees of Barrington

I like bumblebees. They’re big, round, and fuzzy, reminding me of a child’s stuffed animal toy. Where most bees and wasps dart about in a threatening manner, bumblebees are slow, clumsy, and focused on flowers as they gather pollen and nectar. The loud buzz from their wings – where the “bumble” in their name comes from – almost makes them seem like a wind-up toy. If any insects can be said to have charisma, it’s bumblebees.

Last summer I became a volunteer bumblebee monitor. Sponsored by the Barrington Greenway Initiative (BGI), this program was a collaboration between Barrington’s non-profit Citizens for Conservation (CFC) and Lake County Forest Preserve District (LCFPD) to survey bumblebees in Lake County. Over 20 volunteers underwent training on how to identify different species of bumblebees. We recorded bumblebee species and numbers on preserves throughout Lake County, including CFC’s own. Our main goal was to document the presence of the critically endangered Rusty-patched Bumblebee (Bombus affinis), but we also documented other uncommon bumblebee species and gained information that will help guide future restorations to encourage populations of pollinating insects.

Bumblebee monitoring was both challenging and rewarding. Watching bees in the field is like birding in many ways. Some birders are causal and just enjoy the pretty birds they happen across while others are seriously into it. These people know every bird species, every variant, and every vagrant or accidental visitor. They identify birds by song alone and keep lists of what they see. Like birding, bee monitors can dabble in bee studies or go deep down the bee rabbit hole. I found that the greater the effort, the greater the reward.

I used to think of bumblebees as just bumblebees. Superficially they all looked the same and I gave it little further thought. However, with training I became aware of various types and was surprised to learn that ten different bumblebee species are found in Lake County. All ten were documented during the survey. In addition to the endangered Rusty-patched Bumblebee, two local species are declining and listed as vulnerable. These are the Golden Northern Bumblebee (B. fervidus) and the American Bumblebee (B. pensylvanicus). I found all three, and more, in CFC preserves.

Golden Northern Bumblebee

The Golden Northern Bumble Bee is listed as vulnerable. It’s one of the more colorful of the bumble bees with extensive amounts of yellow. (Image by Stephen Barten)

The Golden Northern Bumble Bee is listed as vulnerable. It’s one of the more colorful of the bumble bees with extensive amounts of yellow. (Image by Stephen Barten)

American Bumblebee

The vulnerable American Bumble Bee and more common Black and Gold Bumble Bee and look very similar and multiple characteristics must be compared to tell them apart. Take lots of pictures when you see one of these. (Image by Stephen Barten)

The vulnerable American Bumble Bee and more common Black and Gold Bumble Bee and look very similar and multiple characteristics must be compared to tell them apart. Take lots of pictures when you see one of these. (Image by Stephen Barten)

Identifying bumblebees has a definite learning curve. Those of you who are birders know that there is variability within each bird species. Sometimes males look different from females (Northern Cardinals, Red-winged Blackbirds), or first- and second-year birds look different from more mature individuals (gulls, Bald Eagles). Thus, one must consider several traits rather than just one when making an ID. For birds, we look at things like overall size and shape, color, bill shape, wing length, leg length, foot type, and more. Bees also show variability as the queens, workers, and males of each species have different appearances. In older bees the hair can wear off, revealing the dark exoskeleton and changing their look. Like birds, it is important to consider more than one trait when identifying a bumblebee.

We start by making sure the bumblebee in question is in fact a bumblebee and not one of the mimics. Carpenter bees and several fly species mimic bumble bees and it takes a close look to tell them apart. Things like eye size and position, number and position of wings, antennae length, leg length and structure, amount of hair, and so on can be used to rule out these mimics.

Carpenter Bee

The Carpenter Bee looks a lot like a bumblebee but has a hairless abdomen. Both are pollinators but Carpenter bees are potential pests, drilling their nest holes in soft wood which can include fences, outdoor furniture, and siding. (Image by Stephen Barten)

The Carpenter Bee looks a lot like a bumblebee but has a hairless abdomen. Both are pollinators but Carpenter bees are potential pests, drilling their nest holes in soft wood which can include fences, outdoor furniture, and siding. (Image by Stephen Barten)

Orange-legged Drone Fly

The most obvious difference between bumblebee species is the color of the abdomen. The abdomen is divided into segments called terga. In the Common Eastern Bumblebee, the first tergum is yellow and the rest are black. In the Brown-belted Bumblebee, the first tergum is yellow, the second has a reddish patch surrounded by black, and the rest are all black. The endangered Rusty-patched Bumblebee looks very similar, but the reddish patch on T2 is surrounded by yellow.

Common Eastern Bumblebee

Common Eastern Bumblebee, the most common bumble bee in the summer. Tergum 1 (T1) is yellow and T2 onwards are all black. Note how different views highlight different features such as head, wings, and legs. (Image by Stephen Barten)

Common Eastern Bumblebee, the most common bumble bee in the summer. Tergum 1 (T1) is yellow and T2 onwards are all black. Note how different views highlight different features such as head, wings, and legs. (Image by Stephen Barten)

Brown-belted Bumblebee

Brown-belted Bumblebee, the second most common bumble bee in the summer. T1 is yellow and T2 has a brown patch surrounded by black; the remaining terga are black. Note the full pollen baskets on the hind legs in Fig 2B. The bee in 2C is old and worn and has lost much of its hair, revealing the underlying dark exoskeleton. Most of the hair on the thorax and the brown patch on T2 are missing, making the identification of this individual more challenging. (Image by Stephen Barten)

Brown-belted Bumblebee, the second most common bumble bee in the summer. T1 is yellow and T2 has a brown patch surrounded by black; the remaining terga are black. Note the full pollen baskets on the hind legs in Fig 2B. The bee in 2C is old and worn and has lost much of its hair, revealing the underlying dark exoskeleton. Most of the hair on the thorax and the brown patch on T2 are missing, making the identification of this individual more challenging. (Image by Stephen Barten)

Brown-belted Bumblebee, the second most common bumble bee in the summer. T1 is yellow and T2 has a brown patch surrounded by black; the remaining terga are black. Note the full pollen baskets on the hind legs in Fig 2B. The bee in 2C is old and worn and has lost much of its hair, revealing the underlying dark exoskeleton. Most of the hair on the thorax and the brown patch on T2 are missing, making the identification of this individual more challenging. (Image by Stephen Barten)

Another easily seen identifying mark is the color of the thorax. It usually is yellow with a dark central mark that is either a black dot or a horizontal black band. Less obvious identifying traits include hair length (short or long), face shape (short, medium, or long), and forehead color (black or yellow).

It can be challenging to notice these subtle details on a bee in flight, so it helps to take pictures. Ideally, we photograph multiple angles, including head, side, top, and rear. Using these characteristics, we consult a field guide to attempt an ID, but often struggle with subtle differences and variations. For faster results with more accuracy, we upload our images to iNaturalist at inaturalist.org. We can either enter an ID ourselves or let the site’s algorithm automatically suggest one; more importantly, experts review the images and confirm each ID. I misidentified more than one bumblebee only to have iNaturalist experts make corrections. An iNaturalist “observation” or posting not only documents the observed species, but also the date and location, much like the eBird app documents bird observations for birders. This “community science” generated data is available to researchers who study these species. Anyone can create a free iNaturalist account and any species, not just bumblebees, can be “observed.”

Why learn about bumblebees? Beyond the fact that some are rare or endangered and need protection, they have interesting behaviors and life histories. One of the most interesting is the Lemon Cuckoo Bumblebee. This species is called “lemon” for its yellow color. Cuckoos, of course, are birds that lay their eggs in the nests of other birds and let those birds raise their young. Similarly, Lemon Cuckoo Bumblebees take over the nests of other bumblebees, killing their queen and hijacking the workers to raise their own eggs and larvae.

Lemon Cuckoo Bumblebee

During my bumblebee monitoring surveys I observed a host of other interesting insects, behaviors, and interactions. One of the most unique things I saw was a Common Eastern Bumblebee bothered by a tiny brown dot on its tongue. I took photos and moved on. When I enlarged the images on my computer screen, I found that the brown dot was a tiny beetle clamped onto the bee’s tongue with its mandibles. It turned out to be a Silken Fungus Beetle (Antherophagus ochraceus). These beetles wait on flowers for a bumblebee to approach, then clamp onto a leg, antennae, or mouth part. The beetle is not a parasite but simply hitches a ride back to the bumblebee colony, where it lays its eggs. The beetle larvae eat organic debris in the colony, and after transforming into adults, hitch a ride on another bee back to another flower. This behavior is called phoresy: a commensal relationship just for travel but without parasitism.

Silken Fungus Beetle

Our survey showed that bumblebees thrive in restored prairie habitats and were present on the surveyed preserves in good numbers. The endangered Rusty-patched Bumblebee was seen on 9 of 20 preserves in Lake County. It and the vulnerable Golden Northern Bumblebee and American Bumblebee all were recorded on CFC properties. This is one of many examples of the value of the restoration work that CFC has been doing for over 50 years.

I found bumblebee monitoring to be another way for me to connect to nature and learn more about the world around me. It offers many of the same joys that birding does: the challenge of seeking and finding, collecting life lists and observations, finding that rare “unicorn,” and getting unique photo opportunities. I enjoy it immensely and look forward to gaining more knowledge and experience in coming seasons.

For more of Steve’s bumblebee identification resources, visit bugguide.net, and xerces.org.

About the Author

Stephen Barten is a retired small and exotic animal veterinarian, naturalist, award-winning wildlife photographer, avid birder and herper (reptiles), and bluebird and bumblebee monitor living in Tower Lakes, Illinois.

A long-time Citizens for Conservation volunteer, Steve loves observing animals in their native habitat. He has traveled around the world to observe and photograph wildlife, but always is pulled back to the beauty and variety of birds and wildlife in the Barrington area and his own back yard. He hopes his images inspire others to appreciate and conserve the beauty of wildlife.

View his images at SteveBarten.smugmug.com or follow him on Instagram @stephen_barten. His photography also is featured in the Barrington Area Digital Photo Gallery, at BADPG.org. Click here for Steve’s contributions to 365Barrington.com.