Banded Alder Borer- Rosalia funebris
Just a few weeks ago, a banded alder borer was spotted by a volunteer during a Restoration Work Party held here at SHADOW Lake Nature Preserve! This beetle was found in SHADOW’s Alder Grove.
Although its striking white and black stripes seem like they come from the tropics, the banded alder borer is a Pacific Northwest native. It is commonly mistaken for a lookalike, the Asian longhorn beetle, a destructive and invasive pest that causes severe tree damage by boring wood. Fortunately, banded alder borer beetles feed on dead wood of trees like alder, ash, and other hardwoods. These eating habits expedite the trees’ decomposing process, an integral part of a healthy an ecosystem. For this reason, the native banded alder borer is not a pest but rather a helpful and welcome Pacific Northwest native insect!
Oddly, one of the best places to spot this beetle is around freshly painted houses during hot summer days. Although scientists are not entirely sure what causes this to occur, some believe that the warm paint emits an attracting scent or “pheromone” that draws the beetles in. Because banded alder borers are somewhat uncommon to see, our volunteer was very lucky to spot this beetle in the wild!
Want to learn more?
Found one on my fence , Wooden fence next to some old oak Stumps.
Found one on a patio deck in Victoria, BC near the water. It had blue on it as well. Just awesome. Work was being done in the building but not painting.
My husband has been splitting alder wood on our property that had been downed about 5 years ago. He has spotted multiples of these beetles. They have landed on him and on the splitter. Truly awesome to see fly in. We’ll make sure to leave some debris for them to enjoy.
Found many in a delivery of Oak Mulch in Northern California. It is a beautiful insect. Took my breath away, but am a tad concerned it may cause damage to the house, or fence? Still in awe of it though! Magestic looking!
Found one at work in Corvallis Oregon
Found one in my backyard on Van. Island today, awesome markings!
Saw one in Clearlake california at 930 in the morning on July 2 2023 in a parking lot
Got a couple of good pics too
Found one in our parking lot behind the store in Vacaville, CA
Was painting the house exterior in Napa and one showed up. Very cool looking bug.
I have several visiting my yard in Vacaville. They are wonderful looking but the dog thinks he’s a bug hunter now. I’m staining my fence with oil stain, perhaps that’s why they are around. They are definitely breeding over here.
Was cleaning out some garden beds, adding mulch and found this. This is an Ocean Shores Washington on the bay.
I have a dead tree and I have found several all over the yard, is this good or bad
Found one on a shop window in downtown Seattle today near some newly planted street trees
my buddy Eric just saw one the other day not to far from sidewalk in front of Applebees on SR Ave lol
These are lovely native insects doing their part by helping your dead tree to decompose! Very exciting to have some in your back yard 🙂