Last year around this time (late April or early May) I noticed something strange about the leaves on shoots of my old, reliable ‘Annabelle’ hydrangeas. They looked glued together into a puffy, leaf-shaped balloon. What was wrong?

In fact, they were “glued” or rather tightly stitched together at the edges. Turns out the culprit was the larva of a moth called hydrangea leaf-tier or leaftier (Olethreutes ferriferanum).

Ah, the idiosyncrasies of the English language. That’s not tier like tier (or level), it’s tier like tie-er. Something that ties. In this case, a wee, black-headed caterpillar that laces the edges of the emerging hydrangea leaves with its own brand of silk. This creates a home to grow up in until it’s ready to pupate. If you leave it too long, the flower bud will be damaged. Bad news.

Good news, though: Fixing this is easy and, if you like bursting bubble wrap, even kind of fun. Just pull apart the leaves and squish the caterpillar. Done.

You can probably just make out the silky glue on the leaves in the gallery above. Cursor over the images for the captions, and click any image for the slideshow; the pictures will also become sharper.

Here’s info on the pest, and what to do about it, from the Montreal Botanical Garden, which uses what I think is an older synonym, Exartema ferriferanum. And Toronto blogger Heidi Weidelich of Heidi Ho-rticulture has great info and pictures that helped me ID my problem last year.

Both sites show hydrangea leaf-tier damage later in the season. So get on the bandwagon now, before yours gets to that disfiguring stage. Pop and squish.