Have you tried neem? I spray it on every plant when I get it and never, ever, ever see another aphid, mealey, or mite. You must, however, spray it way early in the morning, or just after sundown, because the oil will cook the plant if left in Texas heat.
Bob

I think it is too hot to spray neem. I've used it in the past in the late evening and it still killed the plant I used it on. I think it needs to be used when we have cooler weather.

Fill a spray bottle with water and a few drops of dish soap. Gently mix and spray the aphids. The soap breaks down the soft coating on their bodies and they die. A little orange oil mixed in helps kill them too.

bill - I have aphids on all my Mexican milkweed and tuberosa no matter what kind of weather we are having. Luckily, so far this year, I haven't seen them yet but I expect to. Since I grow the butterfly weed for the Queen and Monarch butterflies I hesitate spraying mine with anything - so I periodically use a strong water spray only to "wash them away". I never get rid of them all that way, but I can keep them under control. I don't think the yellowing leaves you are seeing now is from the aphids, cause I have no aphids right now and am having the yellowing leaves. I did last year too, so I think they just start dropping lower leaves when it starts to get hot.
If you want to host butterflies, please don't spray with any chemicals.

I don't know what this is worth, but when I get aphids on my water lilies, I mist them with some rubbing alcohol. It's not enough to hurt the fish, just the aphids it hits & then it's gone.

THanks... I'll give the dish soap a try!

i've always heard you should plant the butterfly weed near roses, the aphids will go to the plant they like most-which is normally the butterfly weed and sort of stay away from the roses!!

Hmmm, I agree with okokok. I don't mind the aphids on butterfly week 'cause it seems to keep them off the other plants. Maybe I'm being too tolerant?

It seemed to work for me to have the aphids on the butterfly weed and not on the roses. I think having an infestation like you have would also work in your favor to attract the beneficial insects like lady bugs that will eat them all in no time.

Ladybugs will eat them in no time!! If you have enough, the ladybugs may stay around long enough to lay eggs and bring more ladybugs to your house!!

Stephanie

I have aphids on mine and I have found that they really don't hurt the butterfly weeds at all. The monarch caterpillars chew up the butterfly weeds, and that doesn't seem to hurt them either. They are growing all over the yard. I never spray anything...I figure something else will eat the aphids and I guess they do. Have never sprayed anything here.

I have so many ladybugs here I never have aphids for long! But before I went organic I had terrible problems with them and have had them really stress the milkweed. I had good luck with spraying them with seaweed extract. (can be found at garden centers) It is used as contact fertilizer and supposed to help stressed plants but it seemed to do a good job on the aphids as well.

Here is a link that might be useful: one type of seaweed spray

Those aphids are specific to milkweed, and they don't really do a lot of harm to them. Any insecticide you spray will very possibly harm the monarchs, too, so just hose them off with a strong spray of water. Or, spray some soapy water on them. Really, you don't have to worry that much over them. Milkweed and milkweed aphids go hand in hand.

Milkweeds attract all kinds of insects. There's also the milkweed bug that gets them, as well as, of course, the monarch butterfly. It's interesting, since they are basically toxic plants. The insects eat them to make themselves distasteful to predators.

Sally

I've discovered the perfect instant solution to rid your butterfly weeds of aphid infestation. I've previously had bought ladybugs which disappeared in 2 days,sprayed with water only to see them return next day,sprayed soap water, sprayed alcohol. None of these remendies had helped. My solution is to get a roll of masking tape. Tear off a small strip and gently blot the aphids. It takes about 5 minutes per plant. Don't worry about getting every one. Go back the next day and the ones you had missed will have bunched back up,repeat with more tape. This works.