Crawlies with Cri: Short-horned click beetle

Short-horned click beetle (Danosoma brevicorne)

This week’s crawly is positively clicktastic! Meet the short-horned click beetle (Danosoma brevicorne).
Not only are brevicornes decked out in sparkly Halloween colors year-round, but they are big! Well, big as click beetles go. Most click beetles top out at just over one-quarter of an inch; brevicorne average one-half inch in length.
For all their sparkly boldness, there are only 282 observations of them recorded on iNaturalist, 20 of which are in Oregon.
Because of their relative scarcity, not much is known about brevicornes specifically. We do know they like boreal forests.
Pause for definition – boreal forests are defined as forests growing in high-latitude environments where freezing temperatures occur for six to eight months and in which trees are capable of reaching a minimum height of 16.5 feet and a canopy cover of 10%.
The boreal forest is the world’s largest land biome. The boreal ecozone principally spans eight countries: Canada, China, Finland, Japan, Norway, Russia, Sweden and the United States. It is typically comprised of coniferous tree species such as pine, spruce and fir with some broadleaf species such as poplar and birch.
With so much boreal habitat available, you’d think there would be more brevicornes around. However, they only live along the Cascades and Rockies up into British Columbia. Then there’s a smattering of sightings along the United States/Canada border from Minnesota to the Atlantic.
Suffice to say, we are very lucky to have these big beauties in our area and now is the time to be on the lookout. Adults are active May through July in our backyards.
There has been at least one study linking brevicornes to spruce species. If you recall, our very own state tree the Douglas fir is actually a spruce, and their thick, rough bark would provide brevicornes with perfect hiding spots to avoid predators.
Speaking of predators, that’s why click beetles click, to avoid becoming snacks for hungry carnivores or omnivores.
Their click ability serves a few functions. When they POP! like popcorn up into the air, they will hopefully startle any critter considering them as a meal. Possibly more importantly, unlike other beetles (and various arthropods) they don’t become vulnerable if flipped onto their backs. They just CLICK! and right themselves to either click again, or fly away from harm.
Fun fact: Click beetles differ from all other beetles by being extra flexible. Unlike all other beetles they can move their front parts and first two legs independently from the rest of their body, giving them their “clickability.”
How do click beetles click? They have a spring-latch system. Click beetles have a hinge system with a “peg” on the underside of their head and a “lip” on the underside of their abdomen. When the beetle pulls its head back, the peg latches on the lip. Then the beetle contracts a pliable cuticle against the latch loading the cuticle with elastic energy, like compressing a spring. When the peg is released it fires past the lip and releases a lot of energy quickly.
How much energy? The release can launch a click beetle with accelerations up to 100 times larger than the acceleration felt by astronauts during a rocket launch.
That’s a launch that would bring up the lunch of a lesser critter!