Monitor Lilies And Fritillarias For The Dreaded Red Lily Beetle

Take a walk with me.

I stroll around my gardens several times a day. In early spring, it’s a stroll to see who’s popped up since my last look, then in mid-spring, it’s to see who’s survived the winter and what’s flowering. A few notes taken, and there’s an occasional thrill when I spot something shooting up from the ground that I was certain was a goner. I even found a plant two weeks ago that I hadn’t noticed in 10 years.

These strolls also become part of my IPM program (integrated pest management) where I look for damage from diseases, insects and other interlopers. A hole in a leaf that shows a slug has been at work. Time for slug bait. Curled phlox foliage that can mean thrips (too cold) or mites. In doing these walks and observations, I’m able to stay ahead of those things that can harm my plants and ultimately get early control. This avoids the panic of summertime issues when these things are so much harder to control.

Over the years I’ve suggested, urged and cajoled you to do the same. To make frequent, careful observations in your gardens and landscapes to catch all these issues early so you or your help can deal with them. Oh, and about that 10x loupe that I continue to ask you to buy — get one.

Does IPM work? Is it worth the effort? Are there results? As you will read, there is an emphatic “yes!”

I walked down the front porch steps just 30 feet from my long English-type border, and I noticed that one of my favorite Thalictrums had foliage that’s crispy at the edges in several spots. I make a mental note, the kind that easily gets lost, but I’m not in a panic because it had been dry and Thalictrums don’t thrive in dry soils. This one is written off to cultural issues (not enough water) and I walk on.

Five feet away my garden starts to get dappled with hardy lilies. In all there are over 50 varieties that spot the long border in the sunny and partly sunny areas. When in flower, from June to late September, they range from 3 feet tall to over 8 feet tall. Some are fragrant, but I finally learned to keep the most fragrant varieties farther from the house as their incredible scents can be overwhelming. At a distance, they simply waft and fill the property with their delightful perfumes.

In my trial garden, about 150 feet away, I have another hundred or so lilies that I’ve grown from tiny bulbils or scales that are harvested in late summer. Over the winter, I “trick” them into forming tiny new bulbs. These tiny bulbs, no larger than a pea, go into the trial garden and are grown on for two years then moved into the gardens. These are my insurance lilies that mitigate the damage from chipmunks and voles.

Back on our stroll, I’m gratified that all the new lilies that we planted last fall have finally broken through the soil with signs of life. I get out my phone, access my database and make notes on these. A flash of red. What? I see a sudden flash of red then it’s gone. I leave a flag in the garden so I know where I saw the flash and I run into the house to get a small plastic cup and cover — the kind of cup you can get at fast food places to put ketchup in.

I race back to the garden, I find the spot and luckily, I see the flash of red again. I hope against hope that it’s not what I think, but I won’t know until I’ve captured it. There it is, hiding under one of the lily leaves. I put the little cup under it, tap the leaf and the insect falls into the cup and gets covered. I’m elated to have made the capture, but panic is setting in. This could be the worst thing ever for my lily collection.

I rush over to my office on the other side of the house, covered cup in hand, and head for my small-tool drawer and get out a 10x loupe. My worst fear is confirmed. Looking through the loupe it’s clear that I’ve caught the dreaded red lily beetle, the most feared insect of lily growers that can ravage the foliage, damage the flowers and kill the bulbs. I’d known for years that this beetle was present 5 miles away, but since no one grows lilies near me I thought I was safe. That false sense of security was now shattered.

The funny thing was that just a week earlier I had been reading the reports from the University of Rhode Island where research is being done on the beetle (Lilioceris lilii) and where a predator wasp has been isolated that can control the beetle without the need for chemicals. The research has shown that the wasp is now spreading through Canada and down into New England — but not to my garden.

Back to the garden for a more thorough search. Yes, there were more beetles. One of the suggested methods to control them is to pick them off and squash them. They’re crafty critters, though, who escape and hide the millisecond they sense you. I got six of them, but my task was clear. Get rid of them and keep them gone. But how?

I first wrote about this beetle in this column in 2004 when gardeners on the East End began to see them in their gardens. I hadn’t done much follow-up reading other than to find that some control had been noted with the use of neem oil and with Spinosad, a botanical insecticide. Neither was a sure thing, but when used alternately at three-to-five-day intervals it seemed the beetle could be controlled.

There was one more thing to do, though. The beetles lay their eggs on the underside of the foliage, and to the naked eye they look like a red inch-long thread. Look closer with the 10x loupe and it’s clear that the thread is actually a number of cylindrical red eggs laid in rows. They are easily squished, or the leaf can be removed and put in the trash.

But while I was catching up on my reading about the beetle there was a note that there was an alternate host. Another plant that the beetle could and would live on while looking for lilies to attack. This was the Fritillaria. And sure enough, in the same area of the garden, a couple of large Fritillaria rubras had just finished flowering.

I think I’ve been able to catch the red lily beetle soon enough to control or even eradicate it in my garden, but that may be over-optimistic. Consider, though, that had I not been doing my visual stroll, which is a form of monitoring, I probably would have ended up with an infestation that would devastate a collection of lilies that I’ve been working on for a decade.

For the rest of the season I’ll continue to use the neem oil and Spinosad (Dr. Jacks) on the suggested rotation. There are some notes that Malathion will work, but that stuff is nasty and I haven’t used it for over 20 years. Hand-picking when I catch them and constant searching for the eggs is now on my daily list.

The lesson here is not so much about the lily beetle as that’s just my experience and example. Hopefully, you’ll learn from my experience how important it is to have a close and intimate relationship with your garden and plants. Look, question, investigate then take the least harmful method toward control. Take the time to look at your plants, explore them, tune into the clues that your garden offers and stay ahead of the problems, so you have control and not the insects and diseases.

If you’d like an IPM primer take a look here: piedmontmastergardeners.org/article/integrated-pest-management. Keep growing.