Signs of said borer are subtle. Until you notice the frass. The frass is the digested middle of the stem of whatever plant the borer has chosen as its home. And did I mention that borers like to eat? Why, they're wormy looking munching machines!
|Two things (that I can tell) are going on here, including signs of a borer (frass) and an earwig. This is Lilium 'Eyeliner', an Asiatic that had been damaged by the roofers who threw a plastic tarp over it (hence the necrotic leaves).|
|Here is the hole where the borer entered the lily stem.|
I get a perverse pleasure in finding the hole on the stem and cutting, cutting, cutting upward through the borer's path until I find it. And then cutting the borer. In half. Or better yet, lopping off its head, a feat meaner than you'd think.
Here is a recommendation from Missouri Botanical Garden, an organic method that requires vigilance and persistence.
Borers typically work their way upward first toward the flower. I've just cut stems off above the hole where they entered and then seek it out by cutting upward until I find the little bugger. At least, this way, I've stopped one.
It's not for the squeamish. Wait a minute! I'm squeamish - especially about really gross things like a slimy caterpillar that bores through my lilies.
But we do what we must do. And I get a pair of the sharpest shears I can find and snip, snip, snip. Until I find it. It's no prize, that's for sure. Not in the winning sense. But snipping this larvae to smithereens is satisfying to the vengeance-driven gardener.
While searching for more information for this blog, I found a column I'd written for the Times of Northwest Indiana in July, 2010.
So you might think I'd learned my lesson about borers and lilies. One of the best ways to prevent this pest is to keep the garden relatively weed-free. And one of the climates borers love is wet--which is what we have in my region right now. Everything's squishy, from the soil to the stems of plants that have taken in as much moisture as they can.
|The prize: This borer will bore no more.|
I haven't found any scientific papers on the subject, but I imagine the "skin" of plant parts becomes vulnerable and soft, like our own skin would after soaking in water. As I'd found for my previous column, borers have been around for awhile. According to Penn State's stalk borer fact sheet, in 1927, the USDA reported the insect as one of the top ten most destructive insects.
By the way, the link in the column from Purdue can be found here. While insects and their feeding methods don't change much over the decades, the dissemination of information certainly does.