They aren't aphids. They are milkweed beetles. Leave them alone. Seriously, they won't damage any of your other plants. They eat the seeds of the milkweed, but not all of them.

Turn, walk away and leave them alone.

Happy Gardening.

Look up Milkweed beetle online.

Those look like oleander aphids. I have them on my native milkweed plant and am not sure how to get rid of them except by putting on a pair of disposable surgery gloves and smooshing them.

Horticultural oils are supposed to be chemically inert, non-toxic agents that primarily kill microscopic insects and insect eggs by coating and suffocating them. In particular Volck oil, which is a highly purified mineral compound. Caterpillars should not be affected by their residue and, unless they are heavily drenched, should be able to tolerate minor amounts of spray.

Insect Control: Horticultural Oils

Ralph - I have them on my Butterfly weed also (get them every year). I'm gonna try the horticultural oil. Since most of the aphids are up near the top I will double check and move any caterpillars down to the lower leaves before I spray.

Ralph,

This is going to sound strange, but, the first chance you get, walk around the plants in the daylight, a little away from them too. Check the ground all around them and see if you can find any ant nests. I'll make you a bet, you will find ant nests, and if you do, go buy some Amdro ant killer and feed it to the ant hills or nests only.

Wherever there are alot of alphids, there are ants behind in somewhere. LOL

It will cut down your infestation considerably. Just go see outside, it works.

I have those orange aphids too, and I sprayed them off with the hose.