Leafminers!
We arrived back from Southern California at 3am Friday night, and I immediately bee-lined for the garden. Everything was doing quite well (especially the zuchinni and tomatoes!), with the exception of the chard.
The next morning, I took a closer look at the chard under the light of day. It did not look good.
The wilted leaves looked almost like they had been eaten from the inside out. And, turning a leaf over, it was clear that they had been.
Leafminer eggs. Damn.