You know, it could be something other than insect eggs, including mold. I just repotted this orchid that is growing inside where no insects that I can see are present, and it had something very similar next to the drain hole where both moisture and air where present. I put cinnamon on the roots when repotting just in case.

I think I remember seeing on some documentary that Milkweed was a crucial plant for Monarch butterflies as they are on their migration routes. I don’t know though you if that referred to the foliage for the eggs and caterpillars or the flowers for the butterflies. Could these little hatchlings be Monarchs? I searched it but could only find pictures of caterpillars much further along in their development.

My philosophy on bugs is to ignore them until the horn worms show up. (Then I pull out my .410. ) a) Keeps the anxiety to a minimum. b) Encourages predators. I had only one horn worm survive the wasps this year, and the peppers (especially the SE Asians) were patrolled by an entire herd of assassin bugs! (A fascinating story; wished I'd thought to take pics.) c) Keeps grower alcohol consumption down (see a) above). Moral: Don't worry. If something bad does show up wait a bit to see what kills and eats it. If nothing does, then - and only then - blow it away. Dennis P.S. If a cat shows up to eat them, don't blow it away. It's probably only Minnie. Send her home.

Well, we really need a picture....I think you know that. :-) But, if I were to guess, I'd say that you're seeing what is commonly called slime mold. It's NOT a mold nor a fungus but a simple protist, often unicellular with many nuclei. There are many many different kinds of 'slime molds', but they pose no problem for your tomato plant. A quick Google search about slime mold and their images should shed some light on your mystery.