My milkweed was so covered with aphids to the point the leaves were turning yellow. I tried knocking them off with the hose, but they came right back. So, the other day, I cut it way back, leaving only a few leaves here and there - I put the discarded MW in the trash. Then, I treated the leaves left with insecticidal soap, which killed nearly every aphid. That was just a couple of days ago, and the milkweed is already making new growth. I found one or two aphids today, and I treated them with insecticidal soap. I've never had monarchs at this time of year, so I don't expect to see them or have any possibility of eggs/caterpillars until late summer or early fall when they're heading south. I'm hoping to control future aphids with this insecticidal soap, which doesn't harm most animals. It's unclear from what I've read whether or not it will kill monarch caterpillars. The article said it will kill only some caterpillars, didn't say which ones. The article said it won't kill the hard eggs of ?beetles, I think it was, so maybe it won't kill butterfly eggs, I don't know. About July or August I HOPE I'll have controlled the aphids, and there won't be any. After that, I'd be afraid a female monarch would show up and lay eggs, so I'll figure out what to do then, probably will just leave the the MW alone.

The biggest problem for me, and others I'm sure, in raising monarchs is dealing with the aphids on the milkweed! I hope I've told you something that will help you.

Sherry

Not sure if it would hurt monarch eggs, but dawn dish soap and water works well for the aphids around here. My butterfly weed gets them terrible!

Andrew, That ain't the half of it! Aphids make honeydew that ants feed off of, and it gets on the leaves and the flies start to appear. Common milkweed is not for the faint of heart! I usually just cut the plant and put it in the trash. I found Tropical Milkweed is much better. It does not seem to get as many aphids.

Common milkweed doesn't grow here (Houston, TX area - zone 9a/b), so I can't compare, but my tropical milkweeds (A. currasavica) always swarm with aphids by late summer. They're already starting to show up on my Gomphocarpus aka hairy balls.

There are generally Monarch eggs (which means caterpillars in no time) on my MWs from early spring onward, so any soaps (whether insecticidal or diluted Dawn) are out of the question. I've tried coffee grounds and banana peels -- nothing works. And, as Sherry mentioned, the hose just doesn't cut it. Though, a combination of hosing off and squishing on a fairly regular basis (a couple of times weekly) keeps the numbers down.

I'll just wait for the ladybugs to arrive and stay. Good luck!

Javi, where did you get the info that Asclepias syriaca doesn't grow in Houston, or are you speaking from personal experience? It shows it in the state on bonap?

Since I started planting garlic around my roses I no longer see any aphids on plants that used to be covered. Would it help to plant garlic near the milkweed plants? Would the butterflies mind?

I don't think the butterflies would mind garlic, and they'd probably nectar on the flowers. I might try that. Today, I squished jillions of aphids on the new growth of my MW/Asclepias curassavica. There are ladybugs here, but I never see them on the MW eating aphids. Maybe it's the larval stage of the beetles that eat aphids, but I've seen those larvae on other plants, just not MW.

Sherry