Milkweed, bless its many virtues, regularly gets a bright orange "glow" at some point in the summer. This year it has arrived a little later than usual, but it is now here: the vivid and impossible to miss Oleander Aphid. These are not a native species but they do love a few of our native plants and have become endemic in our region; this means they over winter outdoors and have become part of the garden's ecology.
Now for the good news. In cold climates Milkweed plants are basically not bothered by the pests, and these aphids will not spread throughout your garden outdoors (however it is also common to find these on certain types of Rudbekia, which are equally impartial to their presence).
Although Oleander Aphids cause mostly aesthetic concerns for garden in Manitoba (in warm climates they last longer and impact more types of plants, causing greater concern), there is some potential that a large quantity of the bugs can make it hard for butterflies to lay their precious eggs (the caterpillars, once hatched, certainly do not seem bothered by the aphids).
That said, there is no need to spray or otherwise attempt to banish them with force. Rather, by taking an eco-systems approach you can certainly enlist the support of the aphid's natural predators such as native ladybugs and lacewings. To do this you will want to avoid using any chemical insecticides in your garden and plant beneficial insect-friendly plants such as ground cover thymes, heliotrope, lavender and other flowers rich in nectar.
One other eco-friendly control tactic is to spray down the stems with fast flowing fresh water. This usually breaks the aphid's feeding beak, essentially rendering them mortally wounded. The one caution with this approach is that it can damage Monarch caterpillar eggs which co-occur on the undersides of the Milkweed leaves. To reduce the potential for harm a less vigorous spray of water can be used, and it can be targeted on the stems and tops of foliage.
Or you can simply squish them!
Milkweed is a tenacious plant that bears this burden easily - sometimes its just how the garden works.