Time to look for red lily leaf beetle

red lily leaf beetle by
If you see the red lily leaf beetle on your lilies, take action now. Photo courtesy Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

by Connie Oswald Stofko

Now is the time to start checking your lilies for the red lily leaf beetle, said John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County.

A reader gave me a heads up a few days ago that she had spotted them on her fritillaria, an earlier springtime plant that the pests also damage.

The red lily leaf beetle, which we first talked about in 2015, is a fairly new invasive species in Western New York. It can cause extensive damage to lilies and fritillaria. The pests aren’t a problem for daylilies, which aren’t true lilies.

Watching

Now is the time to get outside to look for the beetle itself, Farfaglia said, or to look for signs that the beetle has been eating the leaves of the lily. If you see signs of the beetle or of damage, treat the plant.

If you had the red lily leaf beetle in a previous year, you have about a 95 percent chance of having them again, he said. Still, he suggests not treating the plant until you actually see signs of the pests.

Pesticide

One way to treat your plant is to use a pesticide. Farfaglia recommends that home gardeners use neem oil because it is less toxic than other pesticides listed on a Cornell factsheet about the red lily leaf beetle. People have had reasonably good luck with neem oil, he added.

Another reason to wait until you see signs of the insect to treat is that the treatment may not work if you do it too early, Farfaglia noted.

However, if you need to treat your plant, do it before the flowers open. Don’t use insecticide on a plant with open flowers.

Pick off the adults, larvae

red lily leaf beetle covered in feces by Law
You can pick the larvae of the red lily leaf beetle off your plants, but many people find the larvae disgusting because they cover themselves in their own feces to fend off predators. Photo courtesy Kenneth R. Law, USDA APHIS PPQ, Bugwood.org

You can also try picking off the red lily leaf beetles.

It’s difficult to pick off the adults because they’re fast. You can try holding a jar of soapy water underneath a branch that has beetles, according to the Cornell factsheet. When disturbed, the adults tend to drop from the branches. Your goal is to catch them in the soapy water as they drop. Wait a few hours before dumping out the soapy water to make sure they have completely drowned.

The larvae are also difficult to handpick, and they’re gross because they cover themselves in their own feces to fend off predators. See the life cycles of the red lily leaf beetle here.

“As disgusting as it is, handpicking really does help,” Farfaglia said.

Try cedar mulch, coffee grounds

In 2017, Farfaglia told us about a gardener who thought that cedar mulch might stop red lily leaf beetles from damaging plants. The gardener noticed that where she had cedar mulch, the red lily leaf beetles didn’t bother her lilies.

He asked gardeners who tried cedar mulch to let him know whether or not it worked.

“I recall hearing from only one person who tried it, and they still had damage,” he said. “I want to hear from more people.”

Another possible remedy is coffee grounds. Place the coffee grounds around your lilies.

Farfaglia hasn’t heard back from any local gardeners who have found that effective, either.

“But there are soil benefits,” he said. “The coffee grounds can add nutrients and organic matter to the soil. If you have extra coffee grounds, it’s worth a try.”

If you tried cedar mulch or coffee grounds, please let Farfaglia know how it worked for you.

“If you tried it, whether your results were positive or negative, I would like to hear,” he said. You can contact Farfaglia at jaf21@cornell.edu or 716-433-8839, ext. 226.

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19 Comments on “Time to look for red lily leaf beetle

  1. We have seen the beetle on the lilies this year and thought it was early for them. Apparently not.

  2. I have lost almost all of my lilies to these nasty creatures!!!
    Picking them off is a continuous battle which I apparently lost.
    I will be waiting several years before I dare to plant any more lilies even though I really miss them and their beautiful fragrant flowers. I’ll just love the rest of my garden for now.

    FYI: I also had them eating at and destroying Easter Lily plants that I had growing in the garden as well. Ugh.

  3. Last year used neem oil and red cedar mulch. Worked like a champ. Just noticed a beetle so I sprayed and mulched again.

  4. I have them around my stargazer lilies. I chose to use insecticide since that is what I had readily available. They have done a good bit of damage to the leaves but since the plants are just starting and the new growth isn’t eaten to shreds I am hoping that this will work. Any idea of how often the larva hatch so I can keep up with them?

  5. I saw some on my fritillaria- didn’t know what they were so thanks for the heads up.

  6. After giving lilies up a number of years ago, I missed them too much. I hand pick the beetles off every 3 days, and apply neem every 3 days, too, especially onto any larvae and on the ground immediately surrounding my lilies. It worked, allowing me to have bouquets of lilies , but I was vigilant.

  7. I’ve been picking the beetles off already. When using neem oil, is it only effective if you spray the beetles, or can you spray the whole plant? Will it kill the beetles that eat the leaves after the spray dries?

  8. I have no lilies left because of those dratted beetles. The frittilaria seem survive the yearly attack. I handpick beetles and have tried the Neem oil spray. I also find the beetles in the fall around the base of the rudbeckia plants. They apparently chew into the stem and cause the stems to fall over. I probed the soil around my one Guinea Hen frittilaria clump and found many beetles in the ground. Disposed of them and have found far fewer on the plant.

  9. A reader shared this tip on Facebook: “I found a couple of these–enjoying one another’s company–on a fritillaria plant. They drop to the ground when they are disturbed, so I like to place a light-colored cloth below the plant when I search for them.”

  10. Susan, you can find some information about the life cycles of the red lily leaf beetle here. Also, the factsheet from Cornell says: This insect spends the winter as an adult, emerges in spring and feeds, lays its eggs the ndies. The larvae hatch in just 4-8 days in late May -early June. This is the most destructive stage. The larvae drop to the soil, pupate and adults appear about 3 weeks later and continue feeding until frost. Mating and egg laying occur in the spring. There is one generation per year. I hope this helps.

  11. Great information will go and check my lilies. I did see some leaves chewed yesterday but didn’t know what was destroying them. Thanks you so much for this post. I will let you know what I find.Marie.

  12. Went out to the Gardner today and saw that my lily leaves were chewed up even more. I found a couple of the beetles in the dirt and one on a leaf. Without thinking I stepped on the o especially on the dirt . And picked off the ones on the plant put them on the driveway and crushed it. Don’t know if I just pushed the ones that were in the dirt died or if I just buried them. I will get the need oil though to make sure I have gotten the best of them. Thanks.

  13. Found two on my lilly’s yesterday. The morning one was much slower to move caught and squished, has a tough body, the afternoon bug took off before I could capture 😖

  14. Bette, maybe the red lily leaf beetles are a little slower in the morning, or maybe they’re slower when the air is cooler. That might help people who are trying to catch them. Thanks for sharing!

  15. I found one on my one lily plant. I immediately crushed it between my fingers and dropped it back on the plant. I heard this method might discourage Japanese beetles , so I tried it with the red pest. Haven’t seen any signs of others and it’s been over a week. In the meantime I keep checking and I’m saving coffee grounds and egg shells for all the plants in my gardens.

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