Dealing with Daylily Aphids

July 27th, 2011

I grow a lot of daylilies, I have grown a lot of daylilies for years. This year I have had an infestation of daylily aphids. This has never happened before, I’m not sure why I was spared previous years, or hit this year. I think maybe the high rain earlier in the summer allowed the foliage to get high and lush, which provided a better more sheltered eating environment for the aphids down deep by the crown, but I’m not sure.

That rain was earlier in the year, lately it has been hot and dry. I noticed weeks ago a section of my “Happy Returns” daylily hedge lying down. I thought at first maybe an animal, or a toddler, had done it. It resembled what you’ll find in the grass after a deer has bedded down for the night. There was also then some yellowing, so I thought maybe it was the drought.

Finally, when watering heavily did not help at all, I thought maybe it was a pest. So I dug down underneath the foliage and found tons and tons of aphids. They had been eating from lower on the leaves causing them
to lack vigor and strength and fall over. Some of the plants looked nearly dead.

I immediately got out my duster and filled it with some diatomaceous earth. This is a white powder substance to us, made up of ground up ancient seashells. But to small soft bodied insects it is like razor blades, and it is a non-chemical way of killing them. So I injected the dust all on the row.

But the foliage was very thick, and I worried I couldn’t get coverage, so later I then cut the most affected ones back to better get at the lower growth. There was so little green left that they really did look dead, and I don’t think they’ll recover yet this year, but daylilies have such strong roots that I’m sure they will be back next year.

Then, next time I was at Lowes, I got a systemic pesticide. If I had caught it earlier my initial efforts may have been enough, but this was a full blown infestation, very progressed, and I had to not only treat the affected plants, but protect the ones not yet attacked. A systemic product doesn’t kill bugs on contact, instead it is taken up by the plant, and then the bugs who eat the plant injest it. A indiscriminate pesticide could kill bees or lady bugs or other beneficial insects, but a systemic one should only get the bad ones, the ones that eat the plant. It was a Bayer product and it says it lasts for 30 days in the plants, providing long term protection that should hopefully get rid of my aphid problem.

Aphids can often be treated without chemicals. When on trees or roses or other plants that stand up straight, you can often blast them off with a hose, use a soap based product, or the diatomaceous earth as I used. However with these daylilies they were really down in deep where they couldn’t really be sprayed away or accessed well with any sort of spray. There was too much daylily foliage providing coverage. A systemic pesticide was really the best solution as I did not need to worry about spraying all the aphids, but only all the affected plants.

In the future, if this happens again, I will know what to look for and hopefully be able to head it off before it gets this bad.

Posted in: Gardening, Troubleshooting »

10 Responses to “Dealing with Daylily Aphids”

Emily Says:
July 28th, 2011 at 9:45 am
IME when an aphid infestation appears, there’s often something wrong with the plant/soil.

If I see only a few aphids here and there and do nothing, inevitably the lacewings and ladybugs show up.

Sorry you had to deal with this – they are truly the pest of pests.
Karina Says:
August 3rd, 2011 at 1:06 pm
Sounds like it was a difficult task, but at least the problem was solved. How long did the process take?
Adnan Says:
August 6th, 2011 at 10:01 am
I am growing tons of Daylilies and Gerberas side by side.Although daylilies are hard to kill plants but I treat them with pesticides and fungicide every month.I’d ocassionally spray them with 6-Benzyl amino purine as well.Result: Huge clumps and wonderful blooms even n zone 10.
John Cardero Says:
August 12th, 2011 at 9:53 am
I had a bout with aphids a few year back and they nearly destroyed my garden. I wouldn’t wish them on anyone.
Sam Says:
December 22nd, 2011 at 9:03 am
Anytime you’re dealing with aphids, you’ll also want to think about whether or not ants are a problem in your garden. This is because oftentimes ants will “farm” the aphids, and protect them from predators, so you might need to get rid of the ants too.
Overhemden Says:
April 25th, 2012 at 10:10 am
A systemic product doesn’t kill bugs on contact, instead it is taken up by the plant, and then the bugs who eat the plant injest it. A indiscriminate pesticide could kill bees or lady bugs or other beneficial insects, but a systemic one should only get the bad ones, the ones that eat the plant.
Cindy Leiby-Smith Says:
January 24th, 2014 at 5:14 pm
Is a systemic product harmful to domestic animals. I want to get rid of my aphid infestation on my daylilies but I don’t want to poison my dog!
Mary Bicknese Says:
October 4th, 2015 at 12:02 pm
After successfully growing daylilies for 25 years, I had a total garden infestation that actually killed most of my daylilies. Those that were not killed were severely mutilated, and most I have (or had) about 200 mature daylilies, and many other perennials, shrubs, evergreens, some annuals, a few roses, and a dozen single peonies. Also many bulbs. It’s a big garden – or was before the aphids showed up. I have very rich soil, and use fertilizer sparsely. Have the same concerns about using a systemic, so have decided to fence off most of the daylily plantings with ornamental iron fencing. I intend to dig up and dispose of the daylilies that were ravaged. Then I will drench my fenced beds with malathion. Daylilies have been my joy for 40+ years – I’ve been gardening for 60 years. This has been a nightmare. Aphids, whitefly and thrips even got in the house. Aphids have been a serious agricultural problem in many food crop fields as well. Vegetables and fruit (especially the “organically grown” on grocery shelfs are full of bugs and scars from predation. I find bugs on the floors in the grocery stores, and flying around and in the bins. Just a bad year? I doubt it.
Tammy Sandbek Says:
July 6th, 2016 at 6:47 pm
Ok….so I am having the same problem right now with the aphids on my daylilies. I want to get rid of but i dont want to kill of the lady bugs and the lady bug larvae…as well as all my praying mantis. Does the systemic products harm them?
Christy Says:
April 24th, 2018 at 9:40 am
Thanks so much for these posts. I too have had lot of daylilies and no aphids till last year. We had 6 inches of rain which brought new problems for oklahoma! I just now sprayed deep down in lily hearts with Neem oil and hope that stops them this early (mid April). I do have systemic drench if not. Appreciate the advice and emotional support from fellow daylily lovers!