Could be snail eggs, or frog eggs.
Although frog eggs tend to be more in a mass, at least the ones I've seen,
rather then a chain or string. If you can see it, it's probably not mosquito
eggs, which are fairly difficult to see.

k30 is right ( as usual ) ) they are snail eggs. Frog eggs are laid in a
large mass, and toad eggs are in a string. Jerri

http://www.fringeweb.com/Ponds/JerrisPond