Yellow bumps on milkweed
Hello! I planted a milkweed this Spring. I've noticed that it had small yellow bumps on the stem--more than when I first saw them a week ago. The leaves look "dusty" in spots and have a couple kinds of bugs on them. I've never had a milkweed and I'm not sure how to help it. Any tips? How do I get rid of the yellow things (assuming I should)? Thank you very much! Miranda
Ramsey County Minnesota
These are Oleander aphids, a common pest on milkweed at this time of year. Aphids are sucking insects and produce a sticky clear substance called honeydew. Honeydew can attract other insects such as ants. Honeydew can also turn black with a fungi called sooty mold. Here is more about aphids: http://www.extension.umn.edu/garden/insects/find/aphids-in-home-gardens/
Aphids reproduce quickly and frequently (hence the high population). You can remove them by running a gloved hand over them and squishing them, blast them with water or simply cut them down and compost the stems. I would not recommend using an insecticide at this time as we are coming to the end of the gardening season and an insecticide will likely affect beneficial insects.
Aphids are consumed by lady beetles, so it appears they have found your aphids which is great. The other beetles in the second photo appear to be immature milkweed beetles. The aphids will die with the first hard frost and their feeding this year won't affect next year's milkweed crop. However, you may see them again at this time of year.
Thank you so much for your comprehensive, quick, and detailed response. It was very helpful! I really appreciate your expertise--thanks again.