Beneficial Insect Files: Bumble Bee

Beneficial Insect Spotlight: Bumble Bee

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Like the honey bee, the bumble bee is an important pollinator as it goes about collecting pollen for its young and feeding upon nectar, a role that has become increasingly beneficial as communities of honey bee  have vanished worldwide.  The bumble bee is also a social insect, divided similarly into three groups:  the queen, the workers and the males.   Beyond these similarities, however, bumble bees are very different from honey bees, both socially-speaking as well as anatomically.

Bumble bees are larger, hairy versions of their cousin the honey bee.  They are often striped yellow and black along the abdomen, but they may be completely black.   Nevertheless, they are distinctive in that they are covered with thick dark hairs called pile.  While honey bees fly quickly and gracefully, bumble bees have a more lumbering and clumsy flight, with a loud and low buzz.  Bumble bees also do not have barbed stingers, meaning their stingers do not remain in the flesh of its target.  As such, the bumble bee can sting repeatedly.  A bumble bee sting is an extremely painful sting with pain and swelling often lasting days.  Yet, bumble bee are relatively harmless unless provoked, or in defense of a nest in close proximity.

Bumble bees also do not overwinter as honey bees do in a colony.  One bumble bee queen overwinters herself and emerges in the spring to begin forming waxy “jars” to store pollen and nectar.  These are soon turned into cells for raising developing bees after the queen lays her eggs.  She continues to be the sole provider for the developing brood until a couple of groups of workers are ready, then they take over the duties  of foraging and building upon the nest, while she focuses on expanding the population of the colony throughout the season.  Unlike honey bees, worker bumble bees are not sterile.  They can and do reproduce to make additional males to support the colony as well as future queens which will later venture out to develop their own colonies.    The original queen tries to suppress the reproduction of her workers early in the season by show of brute force and/or pheromones.   This usually ensures that the first queen will be the mother of the first group of males.

Throughout the season, new queens and males are continually driven out of the nest.  Unlike honey bees, male bumble bees are capable of foraging for pollen and nectar.  They mate with new queens before the queens hibernate for the winter.

Bumble bees have a crop, which is an expanded part of their digestive system, which is used to store nectar prior to digesting it.  They fill this crop as they visit each flower, using their long tongues to suck out the nectar.  They return to the nest and deposit the collection in waxy jars or inject it into larvae cells to feed their young.  Unlike honey bees, bumble bees do not hoard large amounts of honey, seeming content only to save a little for their immediate needs.

As pollinators, bumble bees are being utilized more by man.  Unlike other pollinators, bumble bees are able to pollinate through an additional process called buzz pollination.  In commercial tomato greenhouses, for example, buzz pollination increases pollen release in tomato crops.

Bumble bees are native to the United States and almost exclusive to the northern hemisphere.  Habitat destruction has caused the endangerment of  many species of bumble bee worldwide.  In Britain, for example, nearly two dozen species have become endangered, with several extinct and more vulnerable to extinction.  With the disappearance of honey bee populations worldwide, the need to develop ecologically friendly and habitat conserving practices is underscored.

Did you know?

The familiar buzz of a bumble bee is not caused by the vibration of its wings, but by the vibration of their flight muscles.

Bee’s wings move 200 beats per second, which is up to twenty times faster than our brain’s nerve impulses fire.  Their flight muscles vibrate like a plucked guitar string and do not expand and contract like our muscles.