Bumble Bees: Pollinators Extraordinaire
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Live adult bumble bees photographed at various North American locations.

Bombus sp. at Allegheny National Forest, Pennsylvania
Pyrobombus photographed at Allegheny National Forest, Pennsylvania. Shown with Goldenrod, Solidago sp. [1]

Bumble bees are large flying insects in the order Hymenoptera, family Apidae, genus Bombus. They are usually covered with aposematic colored pile, that is, long, branched hair in "warning" colors of black-and-yellow. Like their relatives the honey bees, bumblebees form colonies, build nests, feed on nectar, and gather pollen to feed their young.

Bumble bees usually establish their nests underground, and they are much less extensive than those of honey bees. A single bumblebee queen is responsible for the initial nest construction and reproduction. Often, mature colonies will consist of fewer than 50 individuals. Bumblebees sometimes construct a wax canopy ("involucrum") over top of their nest for protection and insulation. Nests are not used year after year; the last generation of summer includes a number of queens who overwinter separately in protected spots.

Bumble bee queens that have already mated overwinter until early spring, then finds a hole or crevice in or near the ground. She builds honeypots and brood cells, and begins laying eggs. Small sterile female worker bees develop first, and begin foraging for nectar. As the weather warms into early summer, new brood cells and honeypots are constructed. These new brood cells produce larger adults which in turn are put to work gathering nectar for the colony. In autumn, fledgling queens mate with drones, and begin the cycle again.

Bumble Bees are important pollinators of flowering plants. In this era of declining domesticated honeybee numbers, colonies of wild bumble bees take on additional importance. Bees are a crucial part of wildlife communities - known as ecosystems - because they pollinate plants in their search for their food, nectar and pollen from flowers. Worldwide, up to 40 per cent of the world's food production is due to pollination by wild bees, which include the bumblebee. Bumblebees are increasingly used in hothouse tomato production; the intense vibration produced by the flight muscles is known to efficiently dislodge the tomato flower's pollen, resulting in greater fruit production.

Many plants have evolved over the millennia to take advantage of various insects' ability to spread their pollen from plant to plant. Some plants can only be pollinated by bees because their anthers release pollen internally, and it must be shaken out by buzz pollination. Bees are the only animals that perform this service. Pollination by bees is known as melittophily.

Bee-pollinated flowers fall into two classes:
* Showy, open, bowl-shaped flowers that are relatively unspecialized (e.g. wild roses, sunflowers)
* Showy, complicated, non-radially symmetric flowers that are more specialized (e.g. peas, foxgloves)

Many bee flowers are yellow or blue, often with ultraviolet nectar guides and scent.  The predominate sugar in the nectar is sucrose.


Male bumble bee Bombus griseocollis
Bumblebees can pass on a culture of "cheating," according to a study published online 23 April in the Proceedings of the Royal Society. At their most beneficial, bees enter flowers to collect nectar and take pollen with them as they go. But they can also just bite a hole in the base of the flower and take nectar without pollinating. Bumblebees (Bombus terrestris) that discover holes made by other bees are much more likely to start biting holes and stealing nectar themselves, apparently realizing that crime does pay.

Bumble bees differ from honey bees in many respects, not least of which is their stinger, which does not have barbs like that of the honey bee. Bumble bee stingers can be withdrawn from the victim and reused over and over again. I've been stung by honey bees many times, but never by one of these.  My numerous encounters with these magnificent, ubiquitous insects tells me they are extremely reluctant to use their stingers.

Tricolored Bumble Bee,  Bombus ternarius
Tricolored Bumble Bee, Bombus ternarius
Insect Mimics of Bumble Bees
Bumble bees have a reputation as dangerous. Would-be predators avoid insects with this bright yellow-and-black aposematic coloring. So effective is the bumble bee's defense, there is a whole panoply of insects (chiefly flies) which mimic their appearance and behavior in an effort to ward off attack.
Syrphid Fly 
Syrphid Fly - Mallota sp.

Robber Fly
Robber Fly - Laphria flavicollis

Robber Fly
Robber Fly - Laphria thoracica
Male Brownbelted Bumble Bee - Bombus griseocollis
Male Bumble Bee
Female Robber Fly
Female Robber Fly
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Order Hymenoptera: Bees, Wasps, & Ants
belong to this large order, which also includes sawflies. Most species are solitary, but some, such as the domestic honeybee, exhibit a complex social structure in which exist sterile female workers and fertile male and female royalty.
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