Any natural remedy for keeping aphids off of my milkweed plants?

A steady stream of water on the aphids can also displace them. You’ll need to hold the milkweed plant with your other hand to avoid stem breakage. Using a spray bottle on stream is also effective

Aphids are rampid in my flowerbeds. The best thing I've found is to mix a teaspoon of dish liquid and a teaspoon of cooking oil in a hand-held spray bottle filled the rest of the way with water. Spray the plant, then 1 - 2 hours later, wash off with the garden hose. This works really well on my garden. Hope it helps yours as well!

Go to your nearest garden center and but some ladybugS. Then release them in the vicinity of the plants the aphids are destroying. The ladybugs come in small cartons similar to cottage cheese cartons.

Please look into milkweed (google it) and it's seasonal cycles in the making of a butterfly. I believe the bugs are part of the food chain process from catapilar to butterfly and you should leave them.