When you water, do you spray the plant from above? That might be sunburn from having bright, hot sunshine burn the plants through water lying on the leaves.

Try to water only at ground level, or early in the morning or later in the evening.

Also, tell those bugs to get a room!

LOL I thought it was too funny, I was taking a picture of the plant and saw these two - figured I'd better snap a picture as no one would ever believe me that I saw this!
Thank you for your response - no, I never water when the sun is bright in the sky.
I think these plants have just completed their producing cycle and I'm going to pull them and plant the seeds I've started.