Do aphids harm milkweed plants?

caterwallinSeptember 19, 2009

I was under the impression that the oleander aphids aren't good for milkweed plants, that they suck the juices out of them. Is that true? Could they kill a plant? Or is it okay to leave them on the plant, and maybe the only harm they do to the plant is to make it unsightly due to the honeydew?

I learned some time back on here that ladybugs eat the aphids. I haven't seen many ladybugs this year. Has anyone else? Despite my not seeing many now, I'm sure before too long we'll have tons of the Asian ones here at our place. I used to like ladybugs when all that we had were native ladybugs, but after someone dragged the Asian ones over here, we've been getting swarms of them here in the fall and we can barely stand to walk outside (they bite). For probably about the past ten years the ladybugs have become a real nuisance in the house here in the winter (they get in by the thousands). It might not be a problem for someone who owns a fairly new house, but our house is very old.

From what I see on my milkweed plants, it would appear that the ladybugs aren't doing their job. I have tons of aphids. Do you think a person shouldn't kill the aphids because of the supposedly lower ladybug population (if we kill them, it could be detrimental to the ladybugs)? Just what would be the cause of the lower ladybug population this year? Maybe I shouldn't have killed so many oleander aphids last year, but there were thousands and thousands of them.


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Cathy ~ for what it's worth (since I'm fairly new at butterfly raisin',) I used to have about 10 large milkweed plants (A. curassavica) which were infested with the yellow aphids most of the time. This was when I lived in S. California. I found that when I let the aphids go wild and do their thing, that invariably, lacewings would come and lay multitudes of their eggs in bunches of long stalks on the leaves of the milkweeds. Then their larvae would wander around and eat up most of the aphids, and so make alot more lacewings, which would control the aphids in my entire yard. In short, I was raising lacewings in abundance! Yes, there were more ladybugs there too, enjoying the feast. Now, maybe the cheese done fell outa my sandwich, but I think that if you want the beneficial insects around, you have to have some plants that support large populations of aphids as food for them. After all, the "oleander" aphids didn't infest any other plants in my yard, so the milkweed/aphid combination turned out to be a great thing for me and my butterfly nursery.

    Bookmark   September 19, 2009 at 6:09PM
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Cathy, I do think that eventually they affect the overall vitality of the plant, but I am kind of inclined to agree Mlle. Buttefnly in that if you have food for the beneficials they will come, e.g. ladybugs and their larva, lacewings, and others I'm sure. T kind of take a "wait and see" approach. If the infestation gets so bad that the aphids are creating that black sooty mold on the foliage, particularly the new growth, I wash them down good with the hose, not really getting rid of all of them, but a good number.

If I can see a number of beneficials and their eggs around the yard, I will do nothing because they will have a meal ready for them when they hatch. So, it's kind of like using my own judgment about what, when, and how, or even if. I got so tired of squishing milkweed beetles this year - gross! They were my worst enemy on my milkweeds.

    Bookmark   September 20, 2009 at 1:42PM
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I suddenly have a huge number of red aphids on my otherwise-fluorishing butterfly plant (weed). What's the best way to control them since we don't have any ladybugs either?

    Bookmark   December 31, 2010 at 7:25PM
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Those aren't 'red aphids' but are 'baby' Milkweed Bugs. ;P

I hose down the Oleander Aphids. The Lacewings are everywhere in my garden and their larvae have plenty to munch on even after I've hosed off the Aphids. I have Aphids I leave on my other plants so there is never any problems with the 'extra' food. Ladybugs are also reproducing in my garden as well so I don't think that my efforts in trying to control the Oleander Aphid population by my human methods has caused any harm in the insect world. In fact, for my school bug club I simply go out and wander around in my garden on any given day and can find the necessary life-cycle step of a ladybug which is quite cool! The kids have been able to watch ladybugs grow from egg and have seen each step all in one fell swoop.

I have seen what the aphids have done to MY Milkweed and am NOT fond of these little things. Period.

As for the little red MW bugs? Squish. I'm certain the bug police will be on me soon...

    Bookmark   January 8, 2011 at 10:29PM
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roper2008 (7b)(7b)

My milkweed becomes infested with these little yellow bugs. It is
the milkweed bug, but they do look like aphids. I do not spray
or hose them off because I have baby monarch cats on them. I
was almost going to give up and get rid of my butterfly weed
because of this infestation. What I do now is I inspect my plants,
usually when it starts blooming, every day to see if any of the
adult milkweed bugs are there. They don't come all at once. They
are very easy to spot, being bright orange and black. I get a plastic
cup, add water with a little dishwashing soap. Put the cup under the
bug and throw them in the cup with a stick. A few may get away
but you can get them the next day. This works for me and you
get way less aphids. My goal this summer is to get every adult I
see. My sister saw me doing this last summer and she wished she
had done it because her milkweed was so infested you could hardly
see the stem.

Are these the little bugs your talking about?

    Bookmark   January 9, 2011 at 8:21PM
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First of all, everyone answering on this page apparently does not know that the little yellow specks on the Milkweed pods are Oleander Aphids and not baby Milkweed Bugs. Baby Milkweed Bugs are bright orange and never yellow. Second, the Ladybugs from Asia are called Asian Lady Beetles and are mistaken for the American Ladybugs all the time. So, what is in someone's house that they are calling Ladybugs may in fact be Asian Lady Beetles, which are very similar and the same size. The Asian Lady Beetle has an M right behind the head. They can also be red, orange or even yellow.
As for the Oleander Aphids, they feed on the pods at the end of the season and are not a problem unless you have an extreme amount of them and they become a nuisance. Typically, other insects like the Green Lacewing, American Ladybugs, Ambush Bugs, Harvestmen (Daddy long-legs) and other species keep down the aphid population. I have many Milkweed plants and see the aphids every year with the Milkweed Bugs and other insects. My plants bloom every year and new plants come up every Spring. I have no problem. Also, Milkweed Bugs only feed on the seeds of the pods. They don't feed on the rest of the plant and don't feed on other plants at all. Milkweed Bugs are harmless. Don't worry about them. Never use pesticides for any reason. These chemicals kill many insects and other species. If you think you have too many aphids and they are not being eaten then blast the pods they are on with the jet setting on the hose. If you are not using the seeds or dried pods then you can also remove the pods with the aphids to get rid of them. None of the common insects seen on Milkweed plants will kill the plant or effect other plants in the yard.

    Bookmark   October 13, 2013 at 1:02AM
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I am new to milkweed cultivation for Monarchs . I just noticed in the last week a large colony of the yellow aphids (looked at one with a dissecting microscope and they are bright yellow with 2 black horns coming out of their backs). I sprayed them off but I am sure that I did not get them all. My questions are: 1) Will it deter butterflies if I spray the aphids with a very weak solution of dishsoap? 2) They seem to prefer the seed stalks, should I cut them off? By the way I saw a single ladybug on the infested plant make a quick U-turn when it ran into the aphids, I thought it would be a feast. Thanks, great site for gardening.

    Bookmark   May 15, 2014 at 1:35PM
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The fact that only Milkweeds get Oleander Aphids is a mixed blessing, and one that can be used to one's advantage. Milkweeds are tough plants and I have seen them support seemingly large populations of these bugs without problems.
Only plants grown in too much shade or are otherwise stressed out will succumb.
That being said, large Aphid populations do attract beneficial insects which keep their numbers in check. Aphid wasps, lacewings, hoverflies and ladybugs all benefit from these aphid blooms. When they run out of Oleander Aphids, they clean up the rest of the garden, eating aphids, mites, whitefly and scale.The only caveat: Be vigilant for ELFs and eggs. Eggs and early instars will be consumed as well.
A Monarch generally won't choose a plant with too many aphids for this reason.


    Bookmark   May 15, 2014 at 4:11PM
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Thank you to all of you who have replied to this thread that I started. I have no idea how I missed the answers but I saw them now that seven11 joined the forum and dredged the thread up. :) By the way, welcome to this family of butterfly nuts. Ha.

Every year I have tons of aphids show up here. I despise their method of reproduction because it's much too efficient for them to greatly increase their numbers and make me a lot of work to squish them. I spent so much time doing that last year it grew old in a hurry. After spending several hours a day for weeks smashing them, I thought what a waste of my time! It was really hard to keep up with them and I wasn't getting other things done that I wanted to do.

I've never tried the hose blasting method that I've read about on here that some other people do. I could be wrong but my thoughts on that are wouldn't they just survive the blast, fall to the ground and crawl right back up the plants later that day and they're there the next day to blast at again? That's why I've been squishing them (my daughter gets disgusted by the way they make my fingers a different color and just the idea of doing it with my bare hands). It is very time consuming though and I really am leaning towards blasting them this year.

I have milkweed bugs, but they never really get too bad, so I basically ignore them. Sometimes I'm torn between letting the tussock moth cats live or killing them. I think that they're cute and fuzzy, but yet the more that they eat it leaves less for the Monarchs. If I get as many cats as I did last year though (zero), I guess it wouldn't really matter, but then again, I can't predict if the Monarchs will show up here or not.

I have a few swamp milkweed plants and lots of tropical milkweed that I started. The SMW does little to help Monarchs here because it gets ugly black blotches all over the plants, making them basically inedible for the cats. The TMW do great here, and I'm aware of the controversy surrounding planting them vs. not. I start them with seeds by wintersowing and by taking cuttings late in the season and bringing them in the house over the winter. I won't let them spread by seed again because I had thousands of them come up last year. Previous years I also let them go to seed but only had a few plants come up from seeds. It does make me wonder if they could have the possibility of becoming invasive, but there are other kinds of plants here that I'm more worried about in that way. I have all kinds of weeds that creep from the lawn into the flower gardens and beds; once they're in there they run rampant because I just can't keep up with it all. Creeping Charlie is the most annoying for me. I didn't have time to weed in my upper garden at all last year, and you should see how it has spread in there! Between the weeds and the Oleander aphids here every year, it sure keeps me busy! I love the butterflies though.

On that note, I'll post that I released my first Black Swallowtail butterfly of the year on Tuesday, May 13 that had overwintered out in the tool shed, and we released (my husband did, actually) two today. I still have more BST to come out and also Pipevine Swallowtails and Giant Swallowtails. I'm so ready to get butterfly cats to raise! I've been seeing Cabbage Whites, Wild Indigo Duskywings, Black Swallowtails, and Eastern Tiger Swallowtails so far this year flying around outside. I'm crossing my fingers for me and others to see more butterflies this year than last year because I know it wasn't a very good year for a lot of us. I'm especially hoping for some Monarch(s) to show up here and lay eggs.

    Bookmark   May 15, 2014 at 9:35PM
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wifey2mikey(7a Tulsa, OK)

You know, I've done a little of both - squishing and water... but you know what has worked the best for me? Leaving them alone. Because along come predators and they will clean my milkweed up in a just a few days. Lady bug larvae and that little greenish flat fly larvae - and lacewing larvae. Those guys will clean up my milkweed so fast it's amazing. I'll still wash or squish if it's a TERRIBLE infestation, but once I get the lacewings going, I pretty much leave 'em alone.


    Bookmark   May 16, 2014 at 7:36AM
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Waited for predators to eat the many aphids but now I notice that there is a shiny film on many of the leaves that does not look very good. So I deadheaded all of the seed pods (not the flowers) and carefully sprayed the entire plant with water, removing about 98% of the aphids.

    Bookmark   May 20, 2014 at 5:23PM
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That shiny film is honeydew, the sugary excretion of aphids and other related insects. It's harmless, but gives rise to unsightly sooty mold. Hope you get some Monarchs soon


    Bookmark   May 20, 2014 at 6:36PM
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Tony G(5a)

Whatever you do to control aphids, early intervention is the key. We haven't had an infestation since 2011, but I'm not sure if that's necessarily a good thing. Whatever's eating all the aphids is probably getting monarch eggs and cats too!

Below are 7 ideas to stop aphids from taking over your milkweed. Good luck, Tony

Here is a link that might be useful: How To Control Aphids on Milkweed

    Bookmark   May 20, 2014 at 9:33PM
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