Carp Without Cars

(Wikipedia image by Matthew Field.)

I’ve noticed this bee several times over the past few years: gigantic (bumblebee-sized or bigger), a beautiful golden color all over, with a habit of hovering for minutes at a time, pausing a few seconds in one place, moving a few feet, hovering again, and repeating, in a circuit that causes it to cruise a limited area over and over. Every time I’ve seen it engaged in this “hover patrol” it has been near some flowers being visited by ordinary honeybees, but I’ve never seen the giant golden bee actually land. I might be reading too much into it, but I get the impression that the bee is aware of me; it seems to face me and check me out, then decides I’m uninteresting and moves on.

I’ve seen this bee in our front yard in Carp, and outside the office building where I work in Santa Monica. (I’ve mentioned my ridiculously long commute, right?) Last Sunday William and I watched one patrolling outside some condos on Sandyland Road, as we walked from the State Beach campground (where we spent the night Sunday night) to the marsh and back.

I asked William what he thought the bee was doing. What’s up with that ceaseless patrol? It has to have a reason, I argued. The bee wouldn’t devote all that energy to the behavior unless there was some point to it.

I’ve tried to google for information about the bee before, without success. Today I tried again, and hit the jackpot.

The bee is the Valley carpenter bee, Xylocopa varipuncta. I’m used to seeing the female patrolling the eaves of houses and other wooden structures, looking for good spots to make a nest hole, and I knew that big black bee was a carpenter bee, but I never realized that this big golden bee was the male of the same species. An article from the UC Davis Department of Entomology quotes entomologist Lynn Kimsey as follows:

Carpenter bees, measuring about an inch long, are the largest bees in California. Their eggs are the largest of all insect eggs. The Valley carpenter bee egg can be 15mm long.

The males are territorial, Kimsey said, and can be quite aggressive. They hover and lie in wait for passing females.

“Female carpenter bees sting, but the males don’t have that apparatus,” Kimsey said. “You can pick up the fuzzy males and they won’t sting you.”

User INaturalist at bugguide.net posted this great image of the bee:

INaturalist wrote:

These big chubby guys come out in the spring and fly around in the willows where Coyote Creek flows into the percolation ponds. In Sunnyvale I find them in the Baccharis at the WPC ponds. They have a very short flight season — a couple of weeks and they’re gone. The females are black and yellow. This one is a drone — presumably its only function is to mate, so what is it doing patrolling? Waiting for a receptive virgin queen to emerge?

I think INaturalist’s speculation is probably right: The bee is on the lookout for females, and is patrolling a territory he’s staked out that seems likely to attract them.

So: Another mystery solved. :-)

This entry was posted on Thursday, June 18th, 2009 at 12:17 am and is filed under invertebrates. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.