Carpenter Bees

Carpenter Bees

Carpenter bees (the genus Xylocopa) are large bees distributed worldwide. There are some 500 species of carpenter bee in 31 subgenera.Their name comes from the fact that nearly all species build their nests in burrows in dead wood, bamboo, or structural timbers (except those in the subgenus Proxylocopa, which nest in the ground). 

This 'collection' came from a new house/room that had been sprayed with pesticide - it was left out overnight with the intent of retaking the phograph in better light...the field mice got there first though! Had the evidence not been caught on camera, no one would have believed me, as not a single bee was left at daybreak.

In several species, the females live alongside their own daughters or sisters, creating a sort of social group. They use wood bits to form partitions between the cells in the nest. A few species bore holes in wood dwellings. Since the tunnels are near the surface, structural damage is generally minor or non-existent.

Nonetheless, considerable wood damage can result from many generations of carpenter bees enlarging existing galleries in wood.

Carpenter bees make nests by tunneling into wood, vibrating their bodies as they rasp their mandibles against the wood, each nest having a single entrance which may have many adjacent tunnels. The entrance is often a perfectly circular hole measuring about 16 millimetres on the underside of a beam, bench, or tree limb. Carpenter bees do not eat wood. They discard the bits of wood, or re-use particles to build partitions between cells. The tunnel functions as a nursery for brood and storage for the pollen/nectar upon which the brood subsists.

The noise they make while tunnelling, has had many a visitor check their cellphones for messages as the sound of the bees chomping and tunnelling through the wood, sounds just like a phone on vibrate. They can seem quite aggressive but this is mostly the male, sensing a female it wishes to pursue, or hanging out around an existing nest waiting to 'pick up' a lady friend.

The male will dive-bomb people and animals that approach the nest but can do no harm as it is only the female that is equipped with a stinger.

Carpenter bees can be important  pollinators on open-faced flowers, even obligate pollinators on some, such as the Maypop, though many species are also known to rob the nectar from flowers by slitting the sides of flowers. I have often found them on the roses and they do severe damage.

flickr.com has a beautiful array of photographs under South African Bees II.

Sources:

* Wikipedia April 2008

* Ohio State University - Department of Entemology

* Psyche: A Journal of Entemology