Attacked!

I noticed, idly, a couple of days ago that my adolescent shagbark hickory had lost some leaves on one of its branches. Yesterday, I looked out the window and at least half of the leaves were missing! There were green spines from some of the leaves on the denuded branches, so I assumed someone was eating it.

I took some pictures and posted them on the local neighborhood listserve, and also a local gardening one. The pictures weren't great, and I didn't get a lot of useful information. I dug out my camera with a long lens, and its battery was dead. An hour of charging later, I went out and took some high resolution photos and found these caterpillars. Also residue (previous instars?) on the trunk. And under the tree, it was very unpleasant, it appeared to be raining caterpillar poop (scientific name "frass").



The tree, planted by me as a stick about 15 years ago, is way too tall for me to be able to reach where the caterpillars were to spray with chemicals. Instead, I sprayed them with a high pressure stream of water from the ground, which knocked some of them off the tree, and maybe annoyed the others. But considering how hot it was, it was probably well received by them. I also topped off the bird bath, thinking birds were my only hope.

 This morning, I didn't see any caterpillars when I went out, but I bought some Bt. This is a bacteria that is specific to kill caterpillars and not much else, and doesn't persist in the environment. When I got back, I saw a regular parade of caterpillars making their way from my hickory, across the front walk, and headed steadily north under the azaleas in the shade. For no reason other than vindictiveness, I made it rain Bt on their parade. There was satisfaction in this.

I also preemptively sprayed my only other hickory, on the ground and on the trunk, though it wasn't their direction.

Healthy, established trees should be able to withstand being eaten for as many as two years in a row. Sadly, this tree was subject to big stress last year when the Big Spruce fell. On its way down, its branches grabbed the hickory and bent it double, all the way to the ground. When the crew came to remove the Big Spruce, I pointed out this hickory and said I wanted to save it. They were glad to have it pointed out, because these trees might whip back up and cause injury. As it turns out, it only came partially up. The arborist gave it a less than 50-50 chance to survive. This spring, it seemed to be quite healthy. It leaned, but it was filling out and growing straight on the new growth.

Luckily, it doesn't threaten my house or any powerlines, so I can just allow nature to take its course. If it lives, great, and if not, it just means more light and an opportunity to plant something else.