This is a dying squash plant tucked in behind some carrots (with a few weeds around). It was a volunteer plant that came up where some squash had been growing last year. It was growing fine, then quickly started dying. I thought it might be squash vine borers which are common here.
I used a stick to dig around the base of the plant and came up with these beetles. The picture doesn't show it well, but they are metallic and shiny.
Everything I have read indicates the damage is from squash vine borers, but the beetles appear to be Japanese beetles, which are also pests to some garden plants. Maybe they were just in the wrong place at the wrong time, because now the plant and the beetles are gone.