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Archive - April 2019

bumble bees Bombus spp.

What are Bumble Bees?
Bumble bees are insects. Insects have three pairs of legs, compound eyes and one pair of antennae. Their body has three sections: head; thorax; and abdomen. They have an exoskeleton made of chitin. Bumble bees are classified in the insect Order Hymenoptera: the ants, bees, wasps and sawflies. Bumble bees are further categorized in the insect Family Apidae, the bees. Bees have a thick body with a division between the thorax and abdomen that is easy to see. 

They also have four wings, hairs on the body, stocky legs and long, slender antennae. 

The females have pollen-collecting hairs on the legs or abdomen. The eyes are located on the side of the head. There are no silver hairs on the face as there are in wasps.

What Do They Look Like? 
Bumble bees are large bees that are covered with hairs. They have yellow hairs on the head, thorax and abdomen. The abdomen can have other hair colors, too.

How Big are They?
Bumble bees are about three-eighths to one inch in length.

Where Do They Live?
Bumble bees must have a place to lay their eggs where their larvae and pupae can develop safely. They build nests in which to raise their young. Bumble bees nest in the ground (often in abandoned mouse holes), among leaves on the ground, under tufts of grasses or in piles of wood. They will also nest in nesting boxes made for them by humans, in baskets and in other items that they find. They must live where many native wildflowers grow so that they can gather food from spring through fall. Bumble bee queens also need a place to survive the winter, such as in mulch or rotting logs.

How Do They Reproduce?
Bumble bees have a complex life cycle. In the spring, a young queen finds an abandoned mouse burrow or other similar hole in the ground where she will start her nest. She collects and stores food. Then she lays a few eggs in the nest. These eggs hatch into larvae that go through four stages, or instars. At the end of this period each larva spins a cocoon and pupates. At the completion of development, a female worker emerges from each cocoon. Development from egg to adult takes about five weeks. All workers are females. When the workers reach the adult stage, the queen no longer leaves the nest. She spends most of her time now laying eggs. The workers are responsible for caring for the eggs, larvae and pupae as well as collecting food. There may be several hundred workers in the hive. The workers are usually smaller than the queen. Toward the end of summer, the queen lays male eggs as well as female eggs. These late-summer females become queens, and they mate with the males. All workers, the males and the old queen die in late summer or fall. Only the new queens can survive through the winter. They find a place to overwinter and will emerge in the spring when flowers start blooming.

What Do They Eat?
Bumble bees eat nectar and pollen from a variety of flowers. Adults mainly eat nectar, with the pollen being fed to the larvae.

Does Anything Eat Them?
Birds eat bumble bees. Spiders, ambush bugs, robber flies, assassin bugs, dragonflies and other insects also feed on them. Striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) kill them in order to eat the larvae, nectar and pollen in the hive.

What Else Should I Know About Them?
Bumble bees are long-tongued bees. They specialize in visiting tube-shaped flowers that have nectar too far within the flower for short-tongued bees to reach. They will take nectar and pollen from other flower shapes, too. Bumble bees are important pollinators.

The workers have pollen baskets on their hind legs. The specialized baskets in bumble bees allow for packing pollen with nectar and saliva into a tight mass.

Bumble bees collect lots of nectar from flowers, but they don’t remove the water from it to make honey as honey bees (Apis mellifera) do. Honey bees need to store food for the winter since the colony lives throughout the winter. Since only the young queen bumble bees live through the winter and are not active, they do not need to make a supply of stored food.

Bumble bees are faster workers than honey bees, better pollinators and can pollinate plants longer in the growing season.

Bumble bees are active from March to September. They have the ability to raise their body temperature by shivering so that they can fly when many other insects cannot.

There are 11 species of bumble bees in Illinois. Three of them are considered common, while five species are rare or very rare in the state. The rusty patched bumble bee, Bombus affinis, is a federally protected endangered species that lives in our state.

Like most pollinators, bumble species are in decline. You can help them by taking some simple actions. Leave some clumps of grasses for them to nest in. Plant native wildflowers to provide nectar and pollen. Visit the Habitat Helpers! webpage for more ways that you can help bumble bees and other pollinators.

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