Most likely aphids. Corn tassels are tender and juicy when they first pop up. Aphids love that. If they haven't gotten fuzzy with pollen yet, I would try watering them off or sliding them off with your hands and mashing them at the same time. As long as you reduce their numbers below plague levels it should all be OK. You don't have to get them all.

I had the same problem and they look so awful.
Won't they spread to other near by veggies? That was my main concern in trying to kill more than I could reach by hand (I grow in 3ft hi beds).

This is for corn ear worms/tomato fruit worms( they are the same worm).
When the corn silk first starts to show, lightly coat your hand with corn oil, vegetable oil or olive oil.
Then handle the silk gently to get the oil on the silk.
Repeat every 2-3 days as more silk begins to show.
The bugs will not lay eggs on the oily surface.
This should work on all bugs.
Please let us know what works for you.