As many of you correctly surmised, the mystery orb was a monarch butterfly egg, Danaus plexippus. I was thrilled to see it because our monarch population crashed last year for reasons that still aren’t clear. We’ve seen hardly any since. In fact, the egg was only the second individual monarch I’ve seen in all of 2013.
8 points to Ainsley for getting there first, and 2 points to Martin for pointing out the common thread between last week’s and this week’s mystery. Both Aphis nerii and Danaus plexippus feed on milkweed.
Also, a point to Ted MacRae for noting an aphid photobomb.