Bumble bees are fairly well known insects due to their size, their clumsiness, and their hirsute bodies. While a lot of folks lump them together into one big group, you can actually encounter many different species of bumble bees in your landscape and they can often be identified while they are stopped at a flower. With the growing interest in pollinator gardens there is also rising interest in what pollinators are actually visiting your garden and bumble bees offer one of the easier groups to identify. With some smaller types of bees you would have to capture them and kill them to look for key diagnostic characteristics. With bumble bees you can use your phone to capture some quick pics and use those for identification later, or you can just use your own peepers to spy on them!
If you want to identify your bumble bees, you’ll need to focus on the thorax and the abdomen of the insect and the colors/patterns of the hair that grows on these two body segments. The thorax is where the wings and the legs of the insect are attached and is the second piece of the body. The abdomen is the longest section of the bee’s body and may be more commonly referred to as the butt of the bug.
Traits of the thorax
When examining the thorax you are looking to see what color the bee’s hairs are on the portion near the head and near the abdomen, and also the shape of the bald spot in the center between the wings.
Traits of the abdomen
On female worker bees there 6 distinct sections or stripes that make up the abdomen and they are labelled as T1-T6. Each of these sections will be hairy and the hairs can be different colors or have different shapes. Pairing these traits with what you see on the thorax will help you deduce the identity of your bumble bee visitor.
Three of the best examples to use in the United States to help you implement this guide are the common eastern bumble bee (Bombus impatiens), the two-spotted bumble bee (Bombus bimaculatus), and the brown belted bumble bee (Bombus griseocollis).
In this simplistic diagram you can see the major traits that each of these species exhibits.
For B. impatiens, you would notice a diamond or football shaped bald spot of the all yellow hair thorax and a predominately black abdomen, with the exception being T1 the first section on the abdomen which is yellow. For B. bimaculatus there is a round bald spot among yellow hair and the abdomen has a yellow T1 stripe followed by a T2 section with a yellow “W” or two dots. The rest of the abdomen would be black. Finally, B. griseocollis has a yellow thorax with a round bald spot and the abdomen goes T1 yellow, T2 brown, and then all the rest are black. This bee is of course making a fashion faux pas, pairing a brown belt with black slacks on its abdomen!
Based on that information, what would identify this bee as?
Hopefully you said the brown belted bumble bee!
What to do with what you find?
Those are the basics you will need as you start to identify the bees you find around your landscape. While you can become a bee-watcher for your own enjoyment, you can also use the information you collect to be a part of a citizen science project called Bumble Bee Watch. Your data can help researchers to better understand where certain species are found so we can make better maps and also help us to understand how populations of bumble bees are doing across the country. Consider visiting Bumble bee watch and contributing!
Photos from James Kalisch, UNL Entomology Department
This guide is simplified and focuses only on female worker identification. You may encounter other species or even male bumble bees which can look slightly different than their female nest mates of the same species. There are guides from the Xerce’s Society and many universities that cover that material in more detail. Here are some links those guides if you are interested.
Bumble bees of Illinois & Missouri