ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER

Mission, Texas

Bombus pensylvanicus, American bumble bee, bumblebee, endangered bee

BUMBLE BEES
Bombus

BUMBLE BEES
Genus Bombus

Bumble bees are the best known of wild bees:  they are easily recognized by their robust, furry-looking yellow-and-black bodies and by the loud buzzing sound they make when they zoom by.  Bumble bees' genus name, Bombus,  is Latin for "buzzing" or "deep roar". 

 

Many wild bees are solitary creatures.  Bumble bees, however, have the distinction of being the only native bees in this guide within the family Apidae  that build colonies with a complex social structure, the kind we associate with honey bees. 

 

Like honey bees, bumble bees form colonies that each contain a queen, male drones and female workers.  Queens lay eggs; male drones fertilize the queens; and workers perform various tasks necessary to sustain the colony, such as incubating eggs, feeding larvae and guarding the hive.

 

Bumble bee colonies are more modest in size than those of honey bees. While honey bee hives may contain tens of thousands of bees, bumble bee nests usually harbor a few hundred workers at most.  In addition, bumble bees tend to be far less aggressive than honey bees.  

Female bumble bees carry pollen in rounded masses tucked into pollen baskets, called corbiculae, located on the bees' hind legs and made up of fine, interwoven hairs.  Bumble bees' hefty size allows them to carry relatively large pollen loads, making them efficient pollinators.

The Sonoron bumble bee (Bombus sonorus) shown here was photographed by nature photographer Greg Lasley in Travis County, Texas.   In the field, Sonoran and American bumble bees usually can be differentiated by hair patterns in the thorax:   the typical American bumble bee’s thorax divides into a yellow front portion and black or mostly black back portion.  The Sonoran bumble bee, by contrast, has a largely yellow thorax bisected by a broad black band.  The electric-yellow coloring of the bee shown here is typical of younger Sonoran bumble bees, which become a paler yellow as they mature.  The Sonoran bumble bee is found throughout much of southwestern Texas, but has not been documented recently in the Lower Rio Grande Valley.

Bumble bee corbiculae - (c) Copyright 2018 Paula Sharp

A bumble bee carrying bright orange pollen in its corbiculae (pollen baskets)

American bumble bee - Bombus pensylvanicus - (c) Copyright 2018 Paula Sharp

 The black & yellow bands on the abdomen of a female American bumble bee

A Sonoran bumble bee (Bombus sonorus) - Photo Copyright 2018 Greg Lasley

A Sonoran bumble bee (Bombus sonorus)  Photo Copyright 2018 Greg  Lasley

TAXONOMY OF BUMBLE  BEES

Order:   Hymenoptera

Family:   Apidae

Subfamily:  Apinae

Tribe:  Bombini

Genus:   Bombus
Species shown below:   

   Bombus pensylvanicus (American Bumblebee)

Bumble Bee Species of the National Butterfly Center

American bumblebee

Bombus pensylvanicus

Family:  Apidae

Size:  14-18 mm  (female worker)

Size:  16-22 mm  (male)

Food plants at NBC: 
 

Silver-leaf nightshade

(Solanum elaeagnifolium)
Plant Family:  Solanaceae 

Common Sunflower
(Helianthus annuus)

Blanket flower

(Gaillardia)

Plant Family:  Asteraceae

Esperanza
Tecoma sans)
Plant Family:  Bignoniaceae

When seen:

September 2018  

October 2019 

A female American bumble bee (Bombus pensylvanicus) on a blanket flower

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View of the back of the female bee's abdomen. The patterns of black and gold bands on bumble bees' abdomens are used to distinguish one species from another.

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The female American bumble bee's first abdominal segment is mostly black; the second and third segments are yellow; and the fourth through sixth are black.

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A dorsal view of the female bee. The wings of the American bumble bee are black. The back half of the bee's thorax is also black. Mixed black-and-pale hairs can fringe the back end of the female American bumble bee's thorax, although this trait varies within the species.

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A male American bumblebee. On most male American bumble bees, the first four abdominal segments of the male bee are covered with yellow hairs; the fifth may be black or yellow; the sixth and seventh are covered with black hair. The first segment of this particular male bee's abdomen was covered with a mix of dark and yellow hairs.

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Rear view of male bee's abdomen.

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The male American bumblebee's thorax is pale yellow in front, and black in the middle and toward the rear. The hindmost part of the thorax is covered with a mixture of dark and light hairs.

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All male bees, including male bumble bees, have 13 segments on each antenna. The bottom segment is called the scape; above this is the pedicel, and above this are 11 segments called the flagella.

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Bombus pensylvanicus - Ameican Bumble bee - (c) Copyright 2018 Paula Sharp

A female American bumble bee  (Bombus pensylvanicus) on blanket flower

Bombus pensylvanicus - (c) Copyright 2018 Paula Sharp

A female American bumble bee with its head buried in a blanket flower

Bombus pensylvanicus America Bumblebee; (c) Copyright 2019 Paula Sharp

A male American bumble bee 

The economic importance of bumble bees as crop pollinators is surpassed only by honey bees.  This is in part because tomato-family crops, including tomatoes, peppers and eggplants, require "buzz pollination," in order to bear fruit.  Bumble bees engage in buzz pollination by vibrating their flight muscles to shake pollen from the anthers of flowers.  Many bees, including honey bees, are unable to buzz pollinate.

 

Texas bumble bees / threatened  species:   Eight bumble bee species occur in Texas:  Bombus auricomus, B. bimaculatus, B. fervidus, B. fraternus, B. griseocollis, B. impatiens , B. pensylvanicus, and B. variabilis.  Also found in Texas is the Sonoran bumble bee (Bombus sonorus):  some entomologists classify this as a variation on the American bumble bee (Bombus pensylvanicus); others hold that the Sonoran is a distinct species in its own right.  

Many bumble bee species are currently in decline throughout the United States.  The Texas Parks and Wildlife Department has classified three kinds of bumble bees in the category of  "greatest conservation need" under the Texas Conservation Action Plan:  the American bumble bee (Bombus pensylvanicus); its close relative, the Sonoran bumble bee (Bombus pensylvanicus sonorus); and the variable cuckoo bumble bee (Bombus variabilis).  The International Union of  Nature additionally has placed the Yellow Bumble Bee (Bombus fervidus) on its red list of vulnerable species.

The American bumble bee (Bombus pensylvanicaus) is the dominant bumble bees species of Hidalgo County.  It is well-established at the National Butterfly Center, where it can be observed from spring through mid-autumn.  This species is among the few that pollinate silver-leaf nightshade, a wild Texas plant with showy purple-and-yellow flowers that is a member of the tomato family.  American bumble bees are also frequent visitors of NBC plants in the sunflower family, such as blanket flowers, common sunflowers, cowpen daisies and goldeneye.   American bumble bees prefer open farmland and grassland, and commonly make their nests in shallow depressions under mats of grass.  Their tendency to nest above ground, where they are susceptible to predators, makes them more aggressive than most bumble bees.