Thursday, May 28, 2009
Sigh. Best laid plans, and all that. My plan to create a backyard wildlife preserve, complete with all-native food-bearing plants, has hit another snag. Last winter, it was a rabbit eating the new Red Chokeberry and Sweet Pepperbush shrubs down to the ground. This spring, it was squirrels snipping off all the Flowering Dogwood buds. And now it's Viburnum Leaf Beetle larvae (Pyrrhalta viburni) infesting my Highbush Cranberry (Viburnum trilobum) shrubs.
Small larva, big appetite! This is what's left of my Viburnum trilobum leaves.
I saw the tiny dark larvae on the backs of some pin-holed leaves a couple of weeks ago and I naively thought, Oh good, here are some wormy-like critters for mama and papa birds to feed their babies. Little did I know that birds don't like these larvae. Or at least, they don't recognize them as food. These insects (as I learned by Googling "viburnum insect pests") are twentieth-century immigrants from Europe, not arriving in New York State until 1996. But by now they've spread all across the country, and their favorite foods are our native viburnum species: Arrowwood, Maple-leaved, Nannyberry, and others, especially Highbush Cranberry. And boy, did they eat mine up! Most of the leaves are completely skeletonized, with just a few nibbled ones left on top: a little something for the adults to snack on after these larvae pupate in a couple of weeks. The larvae are now bigger and fatter, yellowish spotted with black, and of course with bigger mouthparts.
I called the nursery where I purchased these shrubs last year, and they said I could use a systemic insecticide that would kill not only these larvae but also the emerging adults. And what about ants and bees and native beetles who visit the shrubs? Oh, well, yes, those too. So that's out. The whole point of planting these native species was to avoid pesticides. There are other, less effective, strategies for battling this beetle, ones that require several years of vigilance and buying bags of ladybugs, but I'm just going to bag up these bushes and pull them out of my garden. Phooey! Darn it all! Dang!
Black Cohosh is also called Bugbane. Let's hope no bugs find it tasty, too.
Happily, my friend at Wildthings Rescue Nursery has provided me some consolation: two Black Cohosh plants (Cimicifuga racemosa), which will grow to be nearly eight feet high at maturity and fill in where I pulled the viburnums out. Their tall snaky flower stalks are fleecy and white and seem to glow in the shadows, earning them the nickname "Fairy Candles." They're also called "Bugbane," producing an unpleasant odor (up close) that's supposed to ward off bugs. Let's hope!!! Let's also hope they don't stink too much, although these ones I photographed at Yaddo last summer didn't seem to smell so bad.
Pretty Canada Anemones will help fill in where I pulled the viburnums out.
I also bought some Canada Anemones, some Celandine Poppies, two darling Birdsfoot Violets, and the nursery threw in one Great Willow Herb, for which I will have to find a sunny spot. And so we move on. Bye-bye viburnums. Let's hope you evolve some immunity to these awful bugs someday. Or some predators discover how tasty Viburnum Leaf Beetles are.