GREEN-BACKED LEAF CUTTER

The leaves on our two sunflowers plants are filagree. Some critter has been nibbling away at the green parts, leaving only a thin web of veins. You can see right through the leaf to the forest beyond.

I’ve been watching these leaves closely for a couple weeks now. I expected to find a malicious caterpillar, or perhaps beetles or leaf-cutters or even a grasshopper (though I’ve never seen a grasshopper in our garden). With all the various birds, including many insectivores, at our feeders, the insect count in our garden seems rather low. Who’s been eating our sunflowers’ leaves?
Here’s who:

That’s it: Lesser Goldfinches. They are daily in our garden for the nyger seed and other seeds. They are known to eat the leaves of ceanothus and perhaps other wild shrubs. I could find no mention in any of my references (including BNA online) indicating they eat sunflower leaves. But they sure do. Fortunately the plants are far enough along that the sunflower seed heads will mature before all the chlorophyll-filled leaves disappear.