30 de novembre 2012

ABELLES FUSTERES

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Foto: Zebra.equus

Les abelles fusteres no són insectes socials i tenen un cicle anual. Generalment són abelles de gran tamany, amb un tòrax pelut i amb un abdomen violeta  brillant, insectes generalment coneguts com a borinots (Xylocopa violacea).

Aquestes abelles deuen el seu nom al forat que fan a la fusta per tal de crear un llarg túnel o dipositarà el po·len i els ous. Any rera any, aquestes abelles mostren preferència geogràfica, reutilitzant antics nius. Durant la posta, que es realitza a la primavera, el mascle realitza un vol de vigilància sobre l'entrada del túnel, mentre que la femella desenvolupa les tasques domèstiques.  

Els nous individus neixerant a l'estiu, i en aquest mateix moment, iniciarant una cursa fins a preparar la nova posta i per tant garantir la pervivència de l'espècie.

Font: Apicesteve i  ichn.iec.cat


 

Carpenter Bees are not social insects; they live only one year. The most common Carpenter Bee, Xylocopa virginica, is distributed throughout the eastern half of North America. This bee is a large insect with a hairy yellow thorax and a shiny black abdomen. Superficially, it resembles yellow and black female bumble bees, which are social and more closely related to honey bees. Western Carpenter bees are also large, shiny, sometimes metallic, and are shaped like bumble bees.

Carpenter bees bore in wood and make a long tunnel provisioned with pollen and eggs. They prefer to enter unpainted wood and commonly tunnel in redwood and unpainted deck timber. They will also go into painted wood especially if any type of start hole is present. New females reuse old tunnels year after year; they are also attracted to areas where other females are tunneling. Egg laying and tunnel provisioning occurs in the spring. Males hover around the tunnel entrance while the female provisions the nest and lays eggs.

Males dart at intruders belligerently but they can do no harm; they have no stingers. Since these bees are not social, there is no worker caste to protect the nest. Stings of females are rare.

New adults emerge after the middle of summer and can be seen feeding at flowers until they seek overwintering sites, sometimes in the tunnels.