Don't know what they are, but you do have a really bad Aphid population going.

Jay

I had to double-check but those are 1st instar (newly hatched) squash bug nymphs. Since that looks like a squash or melon leaf there, it is not too unusual. Squash 'em! ;)

Here is a link that might be useful: squash bug nymph

Thanks. I saw what looked like eggs at one time. Now I know what was in them.

I don't think I've ever seen that many aphids on a cucurbit leaf, ever. Those leaves aren't working anyway because of the aphid sucking.