The Imperiled American Bumblebee

There are some masterpieces worth saving, and the American Bumble Bee (Bombus pensylvanicus) is one of them.  Because of its specific grassland habitat requirements its population is in rapid decline in parts of its historic range.  Rich Hatfield, Senior Conservation Biologist with the Xerces Society for Invertebrate Conservation, says that “the American bumble bee is a highly imperiled animal, and every remaining colony is essential to the immediate and long-term survival of this species.”  We are fortunate to have a population of this bumble bee at Jerry Smith Park Prairie in South Kansas City.

The American Bumble Bee is one of the largest native bees in our area.  They are one of the late emerging bumble bees so you probably won’t see the beautiful yellow and black queens foraging on flowers until June.

The fertilized queen bumble bees hibernate over winter.  When they emerge in the summer they seek a nesting site just above the ground in a large clump of grass.  They build several wax pots in the nest chamber.  Through foraging trips to flowers like Pale Purple Coneflower, Horse Mint, and Beard Tongue Penstemon, they return with pollen and nectar that they deposit in the wax pots.  Eggs are laid in the pot.  When the larva emerge they feed on the pollen and over several weeks develop into worker bees.  The queen then remains at the nest laying eggs and the workers forage for pollen and nectar.  Bumble Bees are one of the few native bees to nest socially.  The rest of the native bees are solitary nesters in the ground or in cavities.

In the fall, the queen lays unfertilized eggs that become male bees and fertilized eggs that become females.  After these bees develop and leave the nest, they mate.  The fertilized females then hibernate over the winter and the rest of the bumble bee population dies.

Many Bumble Bees are more vulnerable to extinction than other creatures.  This is because the bee colony has to remain undisturbed all summer before producing the next generation of queens.  Also because the bumble bees require three different types of habitat to survive – foraging, nesting, and hibernating.  Finally, they often require specific types of flowers for foraging.  Any disturbance in these and the colony dies.  The American Bumble Bee now has declined or is absent throughout much of its historical range.  Scientists think it has declined so rapidly since the 1980s because it has lost much of the specific habitat it needs.  They also think over-use of pesticide may play a role.

This bumble bee cannot survive in your backyard like other species do.  It needs a high quality grassland environment to successfully hibernate, reproduce, and forage.  It has the proper habitat combination at Jerry Smith Park Prairie.  We should continue to maintain this diverse habitat to preserve this American masterpiece.

-Photos and text by Tom Schroeder

Related Local Event:

Native Bees of Kansas City
Tuesday, November 1, 2016 at 6:45pm
Anita B Gorman Discovery Center

Who has more species of native bees on their urban, remnant habitat–Kansas City or St. Louis? Come find out during this fascinating program. Kansas City Wildlands, with support from Burroughs Audubon and The Westport Garden Club through Garden Club of America, have enlisted renowned bee expert, Mike Arduser, to survey bee species, populations and prefered plants on wildlands sites in the Kansas City, MO Parks district. Jerry Smith Park, an 80-acre, never-plowed prairie, and Rocky Point, a preserved and restored limestone glade in Swope Park, are the sites for the bee surveys. Midway through the season, Kansas City comes in with an astonishing 75 bee species, including some very specialized bees that are found only on these undisturbed sites!

The same surveys are going on in St. Louis and we are anxious for the KC wildland sites to come out on top with the most bee species supported. Data from these surveys will not only give us a baseline for management of these ecologically significant locations, but also determine best plant species to be included in future restoration areas.

Come for the unveiling of the results–how many bee species, which bee specialists we have in the KC area and what plants the bees prefer.

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