Thorax of the Honey Bee

Bee Health July 20, 2009|Print

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Thorax

Thorax of the honey bee
Thorax of the honey bee

The thorax is the center for locomotion and has three segments, each with a pair of spiracles for letting in air. Bees have 2 pairs of wings and three pairs of legs. The legs are very versatile, with claws on the last tarsomere, allowing bees to have good grip on rough surfaces (tree trunks etc), but also with a soft pad (arolium) to allow bees to walk on smooth surfaces (leaves or even glass!). There are also special structures on legs to help bee get more pollen.

Pollen Basket

Pollen basket on hind leg
Pollen basket on hind leg

One is called the pollen basket (corbicula), located on the tibia of the hind leg, which is used for carrying pollen or propolis for foragers. It is a concave surface with hairs on the edges and a central long bristle that goes through the pollen pellet or propolis so the load would stay while bees are flying.

Legs

On the front leg, there is a special structure used for cleaning antenna (when too many pollen grains stuck there), properly called the "antenna cleaner".

Front leg
Front leg
Hind leg
Hind leg

Wings

The front wings are larger than the hind wings and the two are synchronized in flight with a row of wing hooks (humuli, singular: humulus) on the hind wing that would hitch into a fold on the rear edge of the front wing.

One set of front and rear wings
One set of front and rear wings
Close-up of hooks that hold the wings together
Close-up of hooks that hold the wings together


The flight muscles exposed
The flight muscles exposed

The wings are powered by two sets of muscles inside the thorax, the longitudinal and verticle muscles. During flight, when the longitudinal muscles contract, the thorax raises its height, so the wings are lowered because of fulcrum like structure (pleural plates) near the wing base. Conversely, when the vertical muscles contract, it shortens the height of thorax, raising the wings. The honey bee flight muscles can contract several times with one single nerve impulse, allowing it to at a faster rate.


Source:
Page text and photos authored and Copyrighted to Zachary Huang, Dept. Entomology, Michigan State University.