I usually just use a strong spray of water and my fingers to assist, to get them off.

Susan

Whenever I go outside to collect Monarchs or leaves, if I see aphids (I almost always do), I squish them with my fingers and it seems to keep the population down. I can't stand to look at them and so they don't live a long time here. We seem to have ladybugs galore in the fall and winter (in the house...those Asian ones..), but come summer when I could use some ladybugs here to help me keep the aphid population in check the ladybugs are nowhere to be found!
Cathy

Brien, I find that the Oleander aphids are pretty easy to control if you remove them at the first sign of infestation. They usually colonize in the growth tips, and I just gently rub them off, which prevents them from ever getting hold.

For a plant that is already heavily colonized, like your photo, I would cut back the entire infested growth tip, and toss it into the compost of something.

I check the milkweed regularly from early in the season for bugs and Monarch eggs, and remove ALL other insects from the plants. This includes earwigs, slugs, beetles, spiders, aphids, hoppers, wasps, etc. Usually I smush them, but lady beetles get a pass and get thrown into another part of the garden. Normally I love a healthy balanced insect population, but not on the milkweed - they either prey on the Monarchs, or degrade the quality of the foliage.

Where are you located? Depending on location it may be too late in the season for monarchs to lay eggs right now. Typically they do not on their way south. Although others on this board have had them lay plenty. I have not. So, I would go ahead and use an insecticidal soap. Again, depending on the health of your plant, aphids can do some serious damage. I have several plants that have not fared well due to the drought and those with aphids look worse. Insecticidal soaps only last a few days and will knock the aphids down for a period.

I just happened to be looking at a paper on this very issue when looked at your post. Here is an excerpt from the conclusion and I have linked it below;

"Our data indicate that the butterfly weeds, A. tuberosa,
particularly �Gay Butterflies� and gooseplant, A. physocarpa,
maintained good plant quality under conditions of heavy
aphid pressure. When milkweeds are being grown as larval
food plants for Monarch butterflies, short-term aphid suppression
with insecticidal soap is an option that may be least
suppressive to butterfly larvae"

Good luck,
Elisabeth

Here is a link that might be useful: Control of Oleander aphids

Thanks for the follow-up everyone. I've been pretty busy and haven't looked at it in detail since the original post. If it is isolated to flowers I'll look at cutting it back. I think it's too much to try and wash off or remove by hand.

I think the lesson learned is to watch it more closely throughout the season and try to nip it in the bud before it gets so bad.

I just saw this post as I was searching for images of an identical problem I have on my butterfly weed. I'm not convinced these are aphids. I think they might, in fact, be ladybug eggs. I'll keep an eye on my plant for a while to see what happens.

I just noticed yellow aphids on one of my Ice ballet milkweed yesterday, I was about to give it a good jet spray of water when I realized I have BST cats on the dill right next to it, and I would hate to blast them accidentally. I would really hate to have damage to my milk weed.
Where is everyone else standing on this topic?

I would try and get them off. If it's not to many, squish them.
If they get out of control, it will make your milkweed really
ugly and grayish looking which is the substance they secret.
Ants and flies like it. Make sure there are no monarch eggs
before you spray it with water.

syzygysb, surely you jest. Aphids suck the sap out of milkweed leaves and decrease germination rate of seeds...not to mention they make your plants look horrible.

Also, a monarch female is not going to lay eggs on a heavily infested plant.

Tony

Syzygysb may have a good point...
I usually only have a problem c aphids on stressed plants, esp ones in too much shade. Aphid colonies are heaviest on these. Monarchs tend to avoid these plants in general, and lay on healthy plants c a light to nonexistent aphid load. Somehow, the "Calvary" comes in and cleans up when aphid counts get too high. Also, healthy plants seem to resist high populations of Milkweed Aphid. So far this season, I haven't seen any aphids.
I feel that a few Aphids contribute to building the "immune system" of the garden by supporting insects such as Hoverflies, Ladybugs, Lacewings, Aphid Wasps and other beneficial insects. I monitor daily for eggs and cats.
Milkweeds in my garden with problem Aphids either get moved to a better location or culled outright.
I've noticed that Tropical Milkweed suffers heaviest here, so I don't bother with it.

John

I always get oleander aphids on my swamp milkweed - always. Sometimes I rinse them off; sometimes, if I see lacewing eggs or lady bug larva I just leave them alone. It's amazing how quickly a few lacewing/ladybug larva can clean up an infestation.

Quite honestly, the plants in my yard that seem to get the highest infestations are the ones in full sun and tend to get stressed during the hottest times of the summer. I have not noticed a correlation between shade and aphid infestations. Right now I have 8 varieties of milkweed in my yard and I have seen aphids on 5 of the 8 species. The ones that seem to get the heaviest infestations are the incarnata and curassavica.

I have also noticed that the plants seem very damaged by the apids if they get out of control. The leaves become very dehydrated, are covered with honeydew and sticky. The leaves also become pale, splotchy, and limp and just don't appear healthy. And they get that sooty mold on them if it goes way too long. I try not to let them get that bad - if nature hasn't taken over then I do.

~Laura

It's quite amazing how everyone has their own experiences with the same plants and pest in different regions. My incarnata generally all get a few aphids, more so than syriaca, but seldom get out of control. Maybe OK is a little hot for incarnata, causing heat stress. I too notice more Aphids during the extremely hot days of Summer, esp during the drought of two seasons ago, but so far this season has been cooler than normal and I have seen few pests yet, except bunnies.
(No Japanese Beetles to date, but I digress.)
What you may also have going on is a sort of arms race between the aphids and the Lacewings; the aphids are just too toxic. Lacewings and Hoverflies in my back yard have no problem eating local Oleander Aphids. This suggests subtle differences between two or more populations of plants/insects from different regions of the country.

I grow incarnata and tuberosa, and last year added curassavica. I've also got an unknown variety in a very shady spot. I always get aphids on the incarnata at some point. The curassavica was also infested, but I worked hard at squishing or spraying them with water. I'm hoping my population of beneficials will help keep them under control this year. I planted Poke milkweed this year, so I'll see how it does. The unknown variety in the shade hasn't had any aphids that I've noticed.

Martha