These eggs have cropped up on a hibiscus. One to three eggs on several leaves. The egg is a little smaller than the head of a pin and seems to be attached by two little protuberances at opposite ends. I haven't yet seen a bug that seems related, although the plant did have a bad case of aphids on its buds. I cut them all off.
p.s. I originally posted this in Pests and Diseases. I was unaware of this forum until someone there suggested I post it here. I believe there's a sanction against double posting, but I think I made a mistake with the first posting.