milk week infestation
We have two types aphids on our milkweed. One is tiny and yellow and the other type is a bit larger and red. We also have black and red buys on it about the size of a box elder. This year is the first year we have had them and they are killing the plants. I have used soapy water but I know it is not good for the Monarchs. Even with the soapy water, the bugs, especially the yellow aphids? have taken over. What can I do? I know it is late in the season but I am still seeing caterpillars. I would like to know for next year.
There are several color forms of aphids. It sounds like you may be seeing oleander aphids, a common visitor on milkweed plants. These can be dislodged with a strong spray of water from a hose, or wear garden gloves and squish them by hand. Here is more information. https://extension.umd.edu/hgic/topics/aphids-got-your-milkweeds
The red and black bugs sound like milkweed bugs. Unless you intend to save seeds from your milkweed, no control is needed. They are mainly a nuisance pest. Otherwise sweep the bugs into a container of soapy water.
Refer to this article for information about them.