Blue Carpenter bee

Blue carpenter bee pictured in Slovenia, 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). Members of the related tribe Ceratinini are sometimes referred to as "small carpenter bees". (wikipedia)