|November Bee of the Month
Above: Male Xylocopa varipuncta on nectar robbing*
Our November Bee of the Month is Xylocopa spp., otherwise known as the carpenter bee!
There are a total of three species of carpenter bees in California: Xylocopa tabaniformis orpifex, Xylocopa varipuncta, and Xylocopa californica. While flight season is year round, you are most likely to see these large, noisy bees from March to August.
But how do you know it's a carpenter bee? While these bees can be confused with some bumble bees and large horse and cactus flies, carpenter bees are shinier and less fuzzy than a bumble, and have two pairs of wings and much longer antennae than a fly. If you're wanting to distinguish between species of carpenter bee, a more extensive guide can be found in our book, "California Bees & Blooms."
Female carpenter bees are generalists for pollen, but in urban gardens can be specifically found on Fabaceae, like Wisteria sinensis (a pollen and nectar source). They can be seen foraging from Lavandula spp. and Salvia spp., as well.
Carpenter bees can be viewed as pests due to their use of wood for nesting habitat. While it is possible for them to drill a nest into the wood of a house, they very commonly use pithy stems and dying tree trunks for nesting-their preference is soft and decaying wood. They are solitary bees, but males and females overwinter in wood in small groups. Female carpenter bees build intricate nests (up to twenty-six cells opposite the central nest) to place a developing egg with pollen and nectar. The egg will develop into an adult bee and will emerge the following spring.
*Note the interesting behavior used to extract nectar. Carpenter bees have small mouth-parts that sometimes inhibit them from accessing the nectar of a flower. To circumvent this, they use their tongue as a knife to slit the base of the flower and "rob" the nectar from the flower. This is called "nectar robbing" because this interaction of bee and flower does not result in pollination.