As far as I know, they pose no threat, but they make a mess of your milkweed! The red and black bugs are milkweed bugs - I have plenty of them on mine!

Sherry

I have some of those critters on my milkweed too, and it has never been a problem. The aphids and milkweed bugs are especially abundant here.
Angie

Over here too! Combined with our humidity the aphids smother out the tuberosa. But the Monarchs are still here too. There are three or four in the yard all day. I never had this many this late in the year. Butterfly house is full of cats.

We've had a plethora of those long horned milkweed beetles up here in WI this season. We have also had a bloom of hover flies, which control our aphids. Haven't seen many milkweed bugs though.

This is good to know...thanks all...however, I have a real problem now! Red wasps!!!! They're stinging and killing all my cats
My heart is breaking...what to do?
Would some sort of netting help????

Gather those cats up immediately and keep them fed.
You can try raising them inside. I start c some of that Oasis wet block floral foam. I wet that and stick my milkweed cutting into it and cover with a wide mouth vase or bell jar. I place the block on a clay saucer to help control humidity. Every two to three days or as needed, replace the milkweed. Defrass the cage and wash and wipe the clay bottom and glassware daily. Do not disturb cats while molting. You'll know when this is happening when they stop eating and become inactive for 12-24 hours. Sometimes they'll crawl off the milkweed and onto the glassware. An hour or so after they molt, they'll be hungry again.
Move final stage cats into an eclosing house with lots of milkweed. They will crawl off in a few days to the top of the cage and pupate Remove all milkweed and frass (poop) at this point. A week or so later, they should eclose.
Releasing a Monarch butterfly is a beautiful experience.