Thursday, August 08, 2013

Valley Carpenter Bee

It may be hard to believe but the 1/2" diameter holes, that have been bored in the trunk of our bottlebrush tree and in a dead apricot stump, were made by valley carpenter bees (Xylocopa varipuncta).

These large bees are not bumble bees, though they do make a loud buzzing sound. And while they are large in size, only the females have a stinger and they are very reluctant to sting. These are bees you should try to attract to your yard. 

male valley carpenter bee
Carpenter bees are native insects and important pollinators. They are more efficient at pollinating than European honey bees, but these native bees are dependent on some of their food coming from native nectar-bearing plants. Many of our sages evolved with these bees.

female valley carpenter bee
There are several species of carpenter bees in the Los Angeles area, but the valley carpenter bee is the largest–typically an inch long. Females are shiny black while the males are a golden yellow.  These large bees are solitary, they do not form a hive.

 The female valley carpenter bee drills into wood, gnawing with powerful jaws. I've watched them and they seem to gradually rotate so that the hole comes out perfectly round. This tunnel into the wood is where she lays her eggs. She places pollen and nectar at the end of the tunnel and lays an egg. Then she closes off the rear section with a pulp wall. In this manner she creates 5-6 small chambers for larva to develop in the tubular nest. When they mature the young bees gnaw their way out of the tunnel and into the world.
female valley carpenter bee arriving at nest tunnel
Females also tunnel into wood to create a hibernation chamber to sleep away the winter. New males will be born in the spring. 

We regularly see several females and an occasional golden-colored male in our garden. They usually follow a regular schedule, visiting specific parts of the yard at the same time each day.

This spring for the first time, I saw two males at the same time. The males were wrestling mid-air struggling over territory. In the end, one of them went off to find a different location.

I love seeing these big bees in the garden. They are gatherers of abundance, yet they are also vital philanthropists spreading pollen as the foundation of tomorrow's garden. 

Plants for native bees:
small bracted dayflower (Commelina erecta)
giant coreopsis (Coreopsis gigantea)
coffee berry 

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