Pest and Life Cycle – (Macrosiphum hellebori) Actually, many different types of aphids feed on Hellebores but this genus does have its own aphid species. They are most active from March to April attacking flowers and foliage, although they are commonly found on the reverse of leaves throughout the summer. The more serious problem with an aphid infestation is the possibility of the spread of virus diseases such as Mosaic and Helleborus Black Death.
Symptoms – Affected leaves and flowers are encrusted with aphid colonies – usually on the face of the flower and the reverse of the leaf. Secondary symptoms (often found on the leaves just below heavy infestations) include glossy patches or black sooty mold (growing on the undigested honeydew secreted by the aphids) often flecked with white molted exoskeletons.
Management – Plants can be sprayed with a contact pesticide containing insecticidal soap and Pyrethrin (Trounce), making sure that you thoroughly cover the affected areas (such as the reverse of the leaf). If the plants are in bloom, spray in the early evening when pollinators are not present. For small infestations you can either squash them or remove the leaf entirely and discard. When dealing with mass plantings, a release of predatory ladybugs should be considered (if they are available at the time).
Prevention – 1. Aphids reproduce quite rapidly so regular monitoring is essential (every 7-10 days) starting in early spring. 2. Remove any weeds growing near Helleborus as these can serve as alternate host or overwintering plants. 3. Many gardeners remove the older tatty foliage (particularly on Lenten Rose or Helleborus x hybridus) as the new leaves emerge. This makes it easier for you to monitor the plant for aphids and it also controls fungal problems such as black spot.
Mike's Garden Guide 
I’ve been trying to use non-toxic sprays and insecticidal soaps and they don’t work. What about red lady bugs?
Ladybugs will work but will quickly disperse once the aphids are eaten. You can also try an organic pesticide called Trounce which combines pyrethrums with insecticidal soap – I use it often on Hellebores and it is quite effective. Cheers. Mike
Should I remove all the leaves the aphids have left black? It’s nearing summer so I’m hesitant to prune too much… but there’s a lot of black on there. Thanks for advice.
If the black is just sooty mold from the aphids it will wipe off or wear off in the rain, so don’t worry about it. Leaves with black fungal spots are another issue, these spots don’t wipe off and the affected leaves should be pruned out providing you don’t remove more than 25% of the foliage. I hope this helps. Cheers. Mike
The Lady Bugs flew away after having a small snack rather than the banquet I offered them. As a result, my hellebores are almost dead. I’ve decided to pull them all out and not replant. I will treat the soil to kill any aphids eggs and plant something else that the aphids don’t like. I’m done with aphids and any plants that they love. The problem with the insecticidal soaps is that one has to spray underneath as well as on top. I have never bought a spray bottle that did not clog up in the process. That said, this is all too much of a waste of my time now. Thanks everyone but I’m done with hellebores.
Hi: I have a few hellebores planted far apart (for now) in a bed covered with bark mulch have had good luck with them, enjoy their cheerful faces in our northwest gloomy winter. Although I did find infested hellebores in another yard whose bed was full of understory, tender greenary. I recommended cut back leaves flat on ground, bag ’em, spray the heck out of rest of plant with neem oil and water – I’ll also tell friend about trounce and to treat soil. Hopefully you could try hellebore again.
Hi Raven, well I gave up. Just not worth it. I’ve tried cutting the hellebores them back but the aphids keep coming back no matter what so I’ve concluded that some plants are just not meant to be in my garden. Thanks anyway.
Having had the usual problem on my Hellebores, (I only had two on my small patio), I cut them both back in anticipation of tossing them in September. One grew back immediately winter came but my favorite didn’t. Couldn’t resist so replaced my Lenten Rose recently only to find that though it had lain dormant for months, (waiting for someone to throw out the heavy pot), it had sprung lots of tiny buds!! I don’t give up easily so am hoping I will not have to fight too hard to keep them pest free. I live in the Northwest.
Wish me luck I will try to find Trounce.
Cecille Samms
I have thousands of lenten roses in my yard, and have been battling a huge infestation of aphids for over a month. I started trying to treat with soapy water in the mornings and hard spraying with water in the evenings. That didn’t work, so I tried spraying with Neem oil – the problem being that I can’t get to all the undersides of the leaves where the aphids are massed. So, after cutting off all of the flower stalks and all the black leaves underneath (I’ve filled 7 large garbage bags with cuttings), I’m going with systemic Bayer’s pesticide, being careful to not spray near any other flowering plants that might have bees. Will treat again in 6 weeks, as recommended. I’m not optimistic that I will get them all, though, as they are most likely on adjacent plants that I don’t want to spray. I’ll give an update in June.
Liz,
With that many Hellebores in one garden creating a monoculture, you are always going to have an aphid problem. If you don’t want to spray systemic pesticides try diversifying the plant material or introducing predatory insects, such as Ladybugs. Cheers. Mike
Thanks, Mike – I had already figured that out, as I was cutting back all the dead foliage. I think I’ll try to get some separation in all my beds, by digging either late fall, or early spring, and maybe spraying with Roundup (which I hate to do, but I’m certain the crowding exasperates the problem). I’d need all the lady bugs in the world to help me at this point!!!
I already pull up any/all babies I see, almost daily, but I obviously have to do more.
Liz
Round-up? NEONICOTINOIDS!!!!!! This is a primary cause of the bee die off and certainly won’t help the lady bugs. Let the damn plants die! I have given up on Hellebores. It’s not worth the hassle. Round-up must be banned.
Ellen,
While I agree with you on not using pesticides and herbicides, an occasional Hellebore in the garden isn’t going to be a big problem and most gardeners learn that too many of any one plant or species can lead to pest issues. Cheers. Mike
I also agree with Ellen, and have never used a pesticide in my garden of 46 years. But, I recently heard a lecture by Dr. Frank Hale, Extension Entomologist at the Soil, Plant and Pest Center in Nashville, and he suggested to me that the big worry about neonicotinoids and bees is with agricultural use on big areas of land. He said that if I don’t spray near any plants with flowers, there shouldn’t be a problem in my yard. I’ve removed all the old flower heads from the lentens, and won’t spray near any plants with flowers (mostly iris right now).
Well, I have two comments. First, like I said, I’m done with Hellebores. Here in Seattle, there are so many other plants that the aphids don’t like that I’d rather just not invest any more of my time on them because the aphids come back every year. They feast on my one remaining plant but it’s coming out and that is that.
Now about Round-Up. It’s evil. So are Bayer and Monsanto. Large agricultural tracks of land or not, we need to get the word out that sustainable gardening practices must begin at home. This means not using these products and supporting organic farmers, especially those damaged by Evil Monsanto. I go nuts when I watch someone using Round-up to kill their dandelions. Really? They’ve never heard of boiling water? IMHO, what it all comes down to education and awareness and I’m doing my part by not using any of it.
Just came across this as I’m having the same issue with a huge infestation on one of my hellebore. There are so many aphids that I see so many on the mulch beneath the plant. What do I do about that, will they survive with the mulch or not, or does that help them to multiply? Will a good spraying of water surrounding the base of the plant be sufficient or should I do something with the mulch and soil beneath?
Try an organic pesticide, spraying the underside of the leaves.
That’s my next move, as I’ve already unleashed so many ladybugs on this one plant and I don’t think it helped. But what should I do with the mulch underneath the plant? It’s got so many aphids all over it…
You can spray both the underside of the leaves and the soil surface with an organic pesticide called Trounce if that is available where you live. You can also just cut off badly infested leaves entirely and dispose of them.
This is so interesting. I live in western Oregon, have had one hellebore in my garden for the past 8 years and have never had an issue with aphids. My years experienced a complete makeover last spring and my hellebore was moved from out in the open to under a Japanese maple. I was just today out gardening and discovered, as the rest of you, a huge infestation of aphids on my beautiful hellebore. I have two hostas, one on each side of the hellebore, and yup, the aphids have gotten to them as well. I cut off and disposed of all the hellebore’s flower stems and saturated the leaves of all 3 plants with neem oil, and am hoping that the hostas will survive and thrive. They haven’t flowered yet. Does anybody know anything about hostas and aphids?