We were in Rohnert Park picking up a burrito tonight (29 June 2024) and noticed several of these long-horned beetles on the outer walls of a building. I couldn't help saying "Whoa!" out loud when I saw the first one.
The black-and-white coloration with blue tints was eye-popping, but so was the size of this beetle. Here's one with a standard key for scale:
Meet the Banded Alder Borer (Rosalia funebris)!
Up close this beetle is even more impressive. Such beautiful coloration!
I'm curious about those large mandibles. Although the larvae eat decaying wood, the adults are said to eat nectar and pollen. Are the mandibles used for jousting?
Banded Alder Borers are native to western North America, but it appears that they are less common along the coast in this area.
I saw several similar beetles at Lake Almanor last weekend. I believed them to be Asian Long-Horned beetles. The long, banded antennae were the same as well as their impressive size. Apparently they are quite destructive to fir trees.
ReplyDeleteLast summer our whole condo complex was painted and they showed up by the dozens… new to everyone. Seems they love fresh paint! I wonder if the wall you photographed it on was freshly painted. Curious and beautiful…
ReplyDeleteHi, Bill!
ReplyDeleteYes, I hear there can be confusion between Banded Alder Borers and Asian Long-horned Beetles, but you can look at the color patterns on the thorax and wing covers to separate them, e.g.,
https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/bandaldbor.html
Jackie
Yes! I also read that Banded Alder Borers can be drawn to fresh paint...and possibly that the smell of the paint mimics a pheromone that the beetles are attracted to. So I wondered the same thing about the building we saw them on.
ReplyDelete:) Jackie
To clarify, I was not suggesting that your photo was an Asian Long-horned beetle. As you said, the color patterns are quite different on the thorax, yet the antennae and size are very similar.
ReplyDelete