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Bees and Wasps

Bumble Bees in Winnebago County, by Barbara Williams

Ten species of bumble bees can be found in Winnebago County.  Some species are quite common, while other species have declined dramatically in the past two or three decades.   Bumble bees are important pollinators of many fruit and vegetable crops.  Loss of bumble bees is attributed to loss of high quality habitat and the irresponsible use of pesticides.  The females may sting, especially when defending their nests, but otherwise bumble bees are almost always docile and inoffensive.

Identifying bumble bees – All bumble bees have six legs, four wings, two antennas with “elbows” and fuzzy abdomens.  Many other insects resemble bumble bees.  Mimicry may help protect them from predators, but it can also fool bumble bee watchers!

Notice the color pattern of the face, thorax and abdomen of a bumble bee.  Each species has a different arrangement of black and yellow bands.  Also notice the texture of the bees’ hair.  A few species have reddish markings on their abdomens that are important to note.

Bees can be very active.  Getting close to bumble bees can be easy, but it can still be difficult to clearly see all the details of a bee. Getting good photographs of the bees you are observing can allow you to carefully examine the bees in the photos later.  Many cameras have a “macro” setting that allows the camera to be held within inches of the bee for a shot.

The largest bumble bees are almost always the queens.  They are the first bumble bees to come out in the spring.  Workers are seen throughout the summer and vary in size.  Some workers are as small as a honeybee.  Males appear in mid to late summer and tend to be intermediate in size.

Eastern Bumble Bee

(Bombus impatiens)

A common and widespread species. All B. impatiens show a pale yellow thorax, generally with a dark spot between the bases of the wings. Only the first segment of the abdomen is yellow. All other abdominal segments are black.

Two-spotted Bumble Bee

(Bombus bimaculatus)

A common and widespread species. The thorax is yellow, usually with a dark spot between the bases of the wings. The first segment of the abdomen is yellow. The second segment of the abdomen is almost always black with two ovals of yellow in the center. The yellow ovals vary in size and may be somewhat blurry. The remaining segments of the abdomen are most often black but in males may show yellow edges or patches.

Brown-belted Bumble Bee

(Bombus griseocollis)

A common and widespread species. The thorax is yellow, usually with a dark spot between the bases of the wings. The first segment of the abdomen is yellow. The second segment of the abdomen is almost always black with an arch of chestnut-brown in the center. The arch may vary in size and extent and may be yellow. Males have extremely large eyes and may show yellow hair on their faces. The hair of the thorax is very dense and even.

Black and Gold Bumble Bee

(Bombus auricomus)

This is a large and dramatic-looking species. They are quite common and widespread. The wings are almost always black. The thorax is yellow, usually with a large dark spot between the bases of the wings. The hind edge of the thorax may be black or show only a few yellow hairs. The first segment of the abdomen is black. The second and third segments of the abdomen are yellow. The remaining segments of the abdomen are black. Males have extremely large eyes.

American Bumble Bee

(Bombus pensylvanicus)

B. pensylvanicus is uncommon in Winnebago County. They appear very similar to B. auricomus (above) except that the center of the first abdominal segment is also partly yellow. Males can show highly variable black & yellow patterns.

Half Black Bumble Bee

(Bombus vagans)

Found occasionally in northern Illinois, much less common farther south. The thorax is yellow, usually with a dark spot between the bases of the wings. The first two segments of the abdomen are totally yellow and the rest of the abdomen is usually totally black. B. vagans is a small bee with shaggy hair. Males have prominent yellow hair on their faces.

Yellow Bumble Bee

(Bombus fervidus)

Uncommon. Thinly distributed but widespread. The thorax is yellow with a neat, dark band between the bases of the wings. Most of the abdomen is yellow. Only one or two segments at the tip of the abdomen are black. The hair on the face is black.

Rusty-patched Bumble Bee

(Bombus affinis)

Formerly common, this species is now rare and only found in isolated pockets of it’s former range. The thorax is yellow with a black spot or a dark band between the bases of the wings. In queens the first two segments of the abdomen are yellow. In the workers and males the first two segments of the abdomen are yellow and the center of the second segment is rusty colored. The remainder of the abdomen is black in all B. affinis. The hair is often somewhat shaggy.

Lemon Cuckoo Bumble Bee

(Bombus citrinus)

Uncommon and found mostly in the northern part of the state. This is a parasitic bumblebee. The queen takes over the nest of another bumble bee species and makes the workers of the other species care for her eggs and larva. Parasitic bumble bee queens only produce more queens and males – no workers. The queens are big, brawny bees with a yellow thorax with a black dot in between the wing bases. The abdomen is almost entirely black except for a dash of yellow on the sides of the third segment or a narrow yellow band around the third segment. Males have thin, shaggy hair. They have a yellow thorax with a dark band or dot between the wing bases. The first three abdominal segments are yellow and the rest of the abdomen is black. B. citrinus bees usually seem sluggish and move rather slowly.

Rusty-belted Bumble Bee

(Bombus rufocinctus)

This bee has been missing from Illinois for a long time and has just recently been found again in the northern part of the state. B. rufocinctus can be very variable but will almost always show rusty coloring on the abdomen. The queens are quite large and the workers are very small – about the size of a honey bee.