One of the bumble bee species in Wisconsin is the Federally Endangered Rusty-Patched Bumble bee which was spotted in Riverside Park in 2018! Photo of a Rusty-Patched Bumble by Jay Watson

A sighting like this is a welcomed reminder that summer is around the corner and it’s time to brush up on knowledge of our Wisconsin bumble bees, honey bees, and their colony dynamics. 

So how are bumble bees different from honey bees? Honey bees are technically invasive species and were brought over from Europe and are more aggressive than our native bees, meaning they will out-compete our native bees over nectar. They also reproduce at a much higher rate than our native bees. Honey bees will have colonies as big as 50,000 individuals, compared to our native bumble bee colonies that are usually 50-400 individuals (can get as large as 1,500).

Photo of both bumble bees and honey bees by Community Scientist Bruce Halmo

Our native bumble bees are the largest bees you will find in Wisconsin, around 1 inch long when other bee species are around ½ to ¾ of an inch long. Bumble bees appear to be fuzzy, are very hairy and have black bodies with patches of yellow or orange depending on the species. Like other bee species, bumble bees are social and live in small colonies with nests in underground cavities once used by snakes or other burrowing wildlife. Bumble bees are also more docile than other bees and will only become aggressive if their nest is being disturbed. They pollinate tomatoes, vegetables, and our native flowering plants.

In spring, keeping an eye out for early blooming native plants to Southeast Wisconsin is a good way to spot the first bumble bees. A few of these plants are Salix discolor (pussy willow), which was the plant shown in the video above, Cardamine concatenata (cut-leaf toothwort), and Viola sororia (common wood violet).

Common wood violet

Cut-leaf toothwort

What makes bumble bees particularly great pollinators? They have a few adaptations that other bees don’t have.

1. They are “buzz pollinators.” That very distinctive buzzing sound you hear when they are on flowers is the bumble bee engaging their flight muscles at a very specific frequency which helps release the pollen onto their bodies;
2. They are hairy. This doesn’t appear to be a big deal, but all this hair increases their surface area making it possible to carry more pollen from flower to flower. The hairs (“setae”) also have very tiny barbs and branches, which makes them extra sticky to pollen - think velcro;

Photo of a bumble bee full of pollen by Community Scientist Jennifer Lazewski

1. They are “generalists." Like honey bees, our native bumble bees are generalists, meaning they can visit a wide range of flower species. They also have an adaptation that allows them to determine what flower species have the most nectar/pollen at any given time. The bumble bee will pollinate a certain flower species until that flower species has depleted its resources. If there are multiple flower species blooming at any given time, the bumble bee colony will “divy up” the flowers, so all the flowers will be pollinated.

Now that you know the difference between bumble bees and honey bees, let's talk about the significance of a queen bumble bee. Queen bumble bees are very much like the matriarchs of the family. Being one of the only surviving members of last year's family, rising spring temperatures awaken them from the ground as they emerge from diapause (a form of hibernation) in early spring, hungry and alone. Needing energy immediately, she will seek out emerging flowers to drink their nectar. This is why early spring ephemerals are so important to emerging queen bumble bees. Once the queen bumble bee has gained enough energy, she will seek out a suitable nesting site which tends to be abandoned animal burrows, under concrete slabs, or in the thick of a healthy prairie.

Once she has selected her nesting site, the queen will create a wax “nest” that she secretes from her body where she lays her first brood of eggs. Then very much like birds, she will sit on her eggs and will essentially shiver to produce enough heat to keep the eggs warm. Once the small larva emerge, they feed on the nectar and pollen that their mother brings back. After about two weeks, they will spin their own cocoons in which they develop into adult bees. This first brood are all “worker” females and will carry out essential duties like guarding, cleaning or foraging for more nectar and pollen to feed the colony and the next brood. 

Many plants will start blooming several weeks after the queens have emerged, just in time for the first wave of worker bumble bees to pollinate the first large wave of blooming plants. Once the first brood has been hatched, the queen will not leave the nest and will lay eggs the rest of summer. 

Body diagram: Female - Elaine Evans

Males are not produced until the middle of summer as they are not “workers.” They do not clean, guard or bring back food for the colony. Their sole purpose is to feed themselves and to mate with the new queens that emerge later in summer. It sounds a bit selfish but if it is any consolation, most males never end up mating. 

The few queens that do mate feed heavily on the last remaining pollen and nectar outside, very much like bears do before hibernation. With this store of energy, they seek out a spot to overwinter which tends to be in old holes, piles of leaves or brush, or in dense grasses. After surviving a cold winter, the cycle repeats itself! These early queens are vital to the success of that year's colony and in many ways to the health and wellbeing of our ecosystem.

What are some ways people can help these incredibly important pollinators? One of the best things to do is to plant native species! Native plant species provide higher quality food as well as support a much wider diversity of insect life. This in turn helps the birds and other animals that depend directly or indirectly on the abundance and diversity of insects. 

In addition to planting native species, becoming engaged with monitoring the health of bumble bee populations is helpful as well all from your backyard! You can help track and monitor bumble bees through Bumble Bee Brigade, which is coordinated through the Wisconsin Department of Natural Resources. This online tool allows users to submit photos of identifiable bumble bees they see to be verified by experts. There are many resources on the site that provide instructions on how to get started as well as guides to start identifying bumble bees. 

One last (and easy) thing you can do to help bumble bees this fall is to actually be lazy during your fall yard cleanup. Bumble bee queens often spend the winter underground or in brush piles like leaves. Choosing not to rake or to have a manicured lawn in fall will potentially create a safe home for bumble bee queens to overwinter successfully.

With all this said, we welcome this unique sign of spring that bumble bee queens bring. We hope everyone can get outside and see one of these beautiful, important, and fuzzy creatures in their backyard or neighborhood. When you see one, remember that these gentle “giants” (compared to honey bees) are doing their part to pollinate your garden, flowers and food. Be sure to give them the respect they deserve by letting them buzz around unimpeded.