Saturday, June 2, 2007

Pleased to Meet You, HopeYou Guess My Name

One of the first things I did when I returned from my whirlwind trip to Arkansas was take a stroll around the yard to see what had changed. The very first thing, after a few minutes of reassuring the cats that I was home and I'd never leave them again (until next time), was to open up all the windows to get some fresh air blowing in the house. Then I headed to the yard.

Most everything looked just like we'd left it but more lush and green, lots of new growth. Except the Arrowwoods. In fact, the two Viburnum dentatum we planted last year looked horrible: nearly every leaf had been skeletonized, with only the leaf veins still intact. And the culprit was obvious, there were little caterpillar-looking things all over them. What in the world were these things? Nothing like I'd seen before. To the Internet!

New "growth" on the Viburnum wasn't looking too well. There is a caterpillar of
some sort stretching down from the webby-looking leaf on the left, but the more
numerous bodies were those of the fleshy thing on the leaf at the bottom-left.

A quick search on "viburnum" and "pest" brought up a Cornell University Department of Horticulture web site that introduced me to Pyrrhalta vibruni, aka the "Viburnum Leaf Beetle." Or, now that we're familiar, VLBs.

A second-instar larvae of the Viburnum Leaf Beetle. Based on most
of the other leaves on the plant, this one is just getting started.

These little buggers are non-native and invasive, typically killing a plant in just two seasons. I learned that they go for a two-pronged attack: first the larvae devastate the plant, in our area usually between late-April and mid-June. Then, after pupating the soil just below the plant, the adults emerge to continue devouring the plant during late June - October (or whenever a killing frost kicks in).

I spent three hours picking off every last one I could find and feeding them all to the catfish in our pond (don't know if they ate them, but they were interested). Since we are adamantly against spraying insecticides, or -cides of any sort, and other devices like traps are indiscriminate in what they kill, I'm hoping to take care of them biologically. Ladybird beetles and soldier beetles, apparently, prey on the larvae and adults, respectively, so I'm hoping they take advantage as they can. Because ideal pupation conditions are not too dry and not too wet I plan on drenching the soil below the plants as often as I can, hopefully making conditions less favorable for survival of the pupae. With luck, we won't see as many adults around as we might have.

A terrible photo, but you can see the larvae as they do their
damage on the emerging flower buds as well as on the leaf.

Of course, all I'm probably doing is selecting for the larvae that hide the best and the pupae that are the most hydro tolerant. Sigh. More updates as the summer progresses.

Post title credit: Sympathy for the Devil (1968), The Rolling Stones

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