The Viburnum Mysteries, Part 1

Most of this past weekend was sunny and warm here in Massachusetts, so I spent a lot of time in the yard. I was supposed to be weeding, but I kept finding interesting things to photograph. During one of my photography breaks I noticed our three Viburnum bushes looked a little, er, chomped:

It didn’t take long to find the chompers:

There were hundreds of them! Even though they were probably not good for my Viburnum bushes, I have to admit feeling a little jazzed at the idea of some butterfly or moth leaving us a giant brood of caterpillars to watch and enjoy. I took lots of photos so that I could properly identify the species later.

Excitement mounted when my sharp-eyed assistant spotted this on an un-chomped Viburnum leaf:

An egg! Look on the top leaf, just right of the center vein at about the center of the leaf. That is an egg! What kind of egg? I’m not sure. But it fed our butterfly dreams. Before the sun set we’d added this clue to our pile of study images:

Certain species of wasp lay their eggs in the safety and relative abundance of a caterpillar body. The eggs hatch and the wasp larvae actually feed on the caterpillar, slowly eating it alive. Gross, I know. But I wouldn’t mind seeing the spectacle once, and it looked as we might have a chance. Plus? This larger caterpillar would surely help us identify the species of insect we were dealing with.

Later, armed with our photographs, several insect field guides, and high-speed internet access, we set out to discover what was living in our Viburnum. It took several hours, mostly because I assumed that all the species we’d found were related. They are not. (Not to self: stop making assumptions!) It seems we are dealing with two species; let’s get the bad news over with first, shall we?

This is the larvae of the recently imported and truly nasty Viburnum Leaf Beetle. Ick. They eat their fill of Viburnum leaves, then crawl down to the base of the plant and pupate in the soil. The adult beetle eventually emerges, flies into the bush and continues to feed on Viburnum leaves. The final insult comes in the fall, when females lay hundreds of Viburnum Leaf Beetle eggs in the woody stems of the shrub … completing the life cycle and setting my poor Viburnums up for an even nastier spring next year.

(The silver lining here is that there is actually a citizen science project tracking the spread of Viburnum Leaf Beetles. And I am now an official contributor! Funny how things work sometimes, eh?)

The truly good news? The eggs we found are not Viburnum Leaf Beetle eggs. And we could find only a few butterfly or moth species that lay eggs on Viburnum leaves in the Northeast. It is possible that we have found eggs that will hatch caterpillars that will eventually pupate into this:

And we Burnses intend to find out for sure:

Stay tuned!