It all started for me when my neighbor, with glee, presented the animated salal leaf she found while gardening. My first thought: “How funny! My second thought, “What insect did this?”
I ran through scenarios in my mind: a variety of caterpillars or sawfly larvae could have randomly chewed what looked like a grimacing face. Loopers or inchworms, perhaps?
Not a weevil, a type of beetle known for the ragged notches it chews, usually starting from the outside edges of evergreens like rhododendron. Weevils are often unseen, feeding at night.
Not a beneficial leafcutter bee, whose characteristic damage is smooth and circular, starting from the margin, swooping inward.
A disease perhaps? Shot hole and other fungus can cause holes in leaves that once the brown, dead tissue disintegrates and falls away, there may be no hint that a disease caused the damage.
Or maybe it was not biotic damage after all (caused a living thing), but rather abiotic (a non-living factor such as weather conditions). Could it have been randomly punctured by sharp sticks as the tender new leaf expanded in the spring or as a dead branch fell on it from above? Torn in a hailstorm?
Like all unsolved plant mysteries, the ghost in the salal haunted me. I began regularly scanning the swaths of salal on hikes, and in my garden. Nothing, until…
This month the ghoulish faces began to reveal themselves to me in great number. Bizarrely, while strolling in a well travelled park amidst huckleberry, and other native plants, I collected 4 salal leaves with haunted faces on the 1 mile path. Who haunts this forested park? Could these faces be markers of good places to find chanterelles–un-noticed by those who don’t know to look for them?
Good mysteries are often never truly solved. My neighbor’s curious salal face was indeed random. However, I think I can say with confidence the other leaf spooks are the result of a biotic agent: a trickster hiker who likes a good autumn mystery.
Research based links from WSU and PNW Pest/Disease Management Handbooks on identifying various insect and disease damage to leaves, some with pictures of types of damage:
Loopers and inchworms:
Leaf cutter bee damage: