by Connie Oswald Stofko
Last year we told you about two invasive insects that could cause problems in your garden: the red lily leaf beetle and the brown marmorated stink bug.
The red lily leaf beetle is the one that causes the most concern right now. It eats lilies and did extensive damage in some gardens last year.
If you had lily leaf beetles last year, expect to have them this year.
Start watching for the red lily leaf beetle now. If you have it in your garden, now is the time to take measures. See more details below.
The brown marmorated stink bug eats a variety of plants, but is so new that its population probably isn’t large enough yet to do extensive damage. You probably don’t have to take any measures against it at this point. However, if you see that it is doing damage to your garden, please let Cornell Cooperative Extension in your county know about it. See more details below.
Red lily leaf beetle
The red lily leaf beetle is a problem for true lilies that grow from a bulb. They also attack fritillaria, a spring bulb that some gardeners like.
The bugs aren’t a problem for daylilies, which aren’t true lilies and grow from a tuber.
According to a Cornell University factsheet, both the larvae and adults feed on the leaves and flower buds.
You can start watching for the red lily leaf beetle now, said John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County, but the weather has been cold and the insect might not be in your garden quite yet. If it’s coming, it should be in your garden by mid-May.
The bug is large enough that you will be able to see it, and it’s bright red with black legs, so it’s fairly easy to identify.
If you had a problem last year, you can approach it a couple ways. You can start a preventive program now (around May 1) or you can monitor your plants and start treating them when you see the insects.
In an ideal world, Farfaglia said, you would go out every day to check your plants and wait to react until you actually see the insect.
“But you don’t want to wait too long because they can do a lot of damage in a short time,” Farfaglia said.
If you can’t get out every day to check your plants for the pest, and you had a problem last year, you may want to start a preventive program now, he said.
Get all the details on how to control this insect in the red lily leaf beetle factsheet from Cornell. If you have more questions, contact the Cornell Cooperative Extension in your county.
Brown marmorated stink bug
Farfaglia said his Cornell Cooperative Extension office got calls about the brown marmorated stink bug because of its annoying habit of taking up residence in our warm houses over the winter. They smell when crushed, hence the name “stink bug.”
He said he had a good half dozen or so in his house. You can get rid of them easily by vacuuming them up or picking them up with a tissue and flushing them down the toilet. He doesn’t recommend spraying insecticide in your home.
I have them in my house, too, and they move very slowly, so they’re easy to catch. We haven’t had them in large numbers either; we generally see them one at a time.
In the house, they’re just a nuisance. But it may be a different story for our gardens.
“We’re still waiting to see how much effect the brown marmorated stink bug will have on plants,” Farfaglia said. “Reportedly, it feeds on a wide range of plants.”
With other pests, such as the red lily leaf beetle, you could deal with the problem by pulling out your lilies (sad as that would be) and planting a different ornamental plant the insect doesn’t eat. If the brown marmorated stink bug feeds on many different fruit and vegetable plants, this could become a big problem for farmers as well as home gardeners.
This year, Farfaglia isn’t expecting to hear about a lot of damage from the brown marmorated stink bug.
“I don’t think we have a large enough population for them to cause extensive damage,” Farfaglia said, “but like most invasive insects, the population could reach those levels.”
He pointed to the emerald ash borer, which was detected only about five years ago in Western New York, but has killed a large number of ash trees.
For the brown marmorated stink bug, at this point “there is no value in doing preventive treatment,” he said. If you get damage, you could start a treatment.
See more information about controlling the brown marmorated stink bug here or contact the Cornell Cooperative Extension in your county.
And if you do see damage in your garden from the brown marmorated stink bug, please contact the Cornell Cooperative Extension in your county.
“We heard about the red lily leaf beetle from local gardeners,” Farfaglia said. “I love feedback on that type of thing. It’s very helpful.”
Maureen, I’m hearing that from many gardeners! Thanks for the update from Rochester.
I pulled probably 20-30 off my asiatic lilies today in Rochester, plus many leaves with eggs, as well as some larva already! They are such a pain!
I have squashed 3 adults on my lilies already this year. I saw the evidence last year and so was on the look out this year because of your article. I’ve been spraying my lilies with a insecticidal soap, but the frequent patrol of plants is probably more effective. Would they be laying eggs yet? I found suspicious yellow dusty substance and wondered if that was related.
I suspect I will have them this year. I took plants from a friend whose garden got invaded shortly after. I have many lilies too.
Sadly they have invaded my garden! Tonawanda
Pat, sorry to hear about the problems you have had. Thanks for that information. (Readers, Avon is south of Rochester.)
Thanks for the “heads up”! We had red lily beetle last year and found some success in spraying with neem oil. I will be on the look out for these destructive pests and start a spray regimen as soon as needed. For anyone who wants to make their own neem oil spray here is the recipe:
1-2 tsp. neem oil, 1/3 tsp. insecticidal soap (or dish soap), 1 qt. warm water. Spray when the sun will not be shining on your plants to prevent burning the foliage.
I found red lily beetles more than 3 weeks ago in my Avon, NY garden during a brief warm up. I’ve been removing lily bulbs for several years and yes they now attack the frittalarias. I’ve also found them feeding on rudbeckia stems in the fall after the lilies have been destroyed. Control is very difficult.