At this time of year, there is a seemingly endless variety of mysterious eggs to be found all over the landscape. In browsing through my folders of unidentified invertebrate signs just now, I came across photos of two different types of eggs I found on the undersides of yellow water lily (Nuphar variegata) leaves in western Massachusetts on June 21, 2008. I still have no idea what they are. Any ideas?
These oval, yellow eggs were embedded in a clear, gelatinous matrix, in a mass 7 mm across.
These brown, slightly more squat ones were more densely packed and, I think, without a gelatinous matrix. The mass was 19 mm long.
Added 7/4/2013: Noah reminds me (in a comment below) that these and other photos of unidentified aquatic eggs we found while working on Tracks & Sign of Insects are collected here.
BugTracks 
Charley, I think the eggs in gelatin could be mites. I have a photo of something quite similar, but with hatched tiny mites moving around inside it, on the underside of a Nymphaea leaf from last summer. The second one I don’t recognize. I’ve spent some years looking at what’s on Nymphaea and Nuphar leaves, but only in my lake in northern Vermont.
Wow, that possibility had not occurred to me. I don’t think I’ve ever seen a reference to eggs of water mites. Based on the limitations of the lens I had at the time, I’d estimate that mass was 7 mm across, which I suppose wouldn’t be out of the question for one of those big Hydrachna species. I’d love to see your photo.
Some more pictures of such eggs are on our old aquatic mystery page from 2008ish, some of these we’ve solved, but not most of the eggs…any new thoughts? http://www.sharoncharney.com/noah/aquatic/eggs.htm
Hmm… Nope. Looks like we have a lot left to figure out.
Hi Charley,
I checked with a water mite expert and the upper image doesn’t look right, but the lower image of brownish eggs could be water mites. She’d need a higher resolution image to be sure.
Cheers,
Dave
Thanks for checking! Maybe someday I’ll get around to collecting these things and see what hatches.
Very cool. It’s never even occurred to me to look on the bottom of lily pads!