The rush milkweeds are lovely this week.
Here is what the plants looked like on March 19, a month ago.
What did I do to get such clean plants?
Nothing. Let nature take its course.
Insects like aphids have boom and bust cycles.
The aphids were also being eaten by flower fly larvae, aphid flies, and a few other insects.
Inside, the plant might have been mounting a defense, too. Plants can increase their chemical fortifications in response to insects feeding on them. Milkweeds are well defended because they contain cardenolide toxins, as well as a milky latex. The aphids can overcome the plants toxins better than most insects, but eventually it is probably has a toll and the aphids are weakened.
Although they are gone right now, the oleander aphids are likely to be back again. It is a natural cycle.