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Red Lily Beetle (Lilioceris lilii)

Pest:  Red Lily BeetleThe Red Lily Beetle has received a great deal of press lately; some alarmist gardeners cry, "Woe is me!" but others with a more practical viewpoint say "OK, so what do we do now?" Although B&D Lilies is in the rainy Northwest and there are no Red Lily Beetles in our region, we have been asking our customers in the New England States about their favorite methods of dealing with this relatively new pest. They share that control of the beetle is not expensive, nor requires massive amounts of pesticides or even an overhaul of the garden, but rather common sense, diligence and a little hands and knees work.

Lilioceris lilii,commonly known as the Red Lily Beetle, Lily Leaf Beetle or Crimson Lily Beetle is native to Eurasia and has most likely spread into North America from either non-inspected "bootleg" (smuggled) imports or poorly inspected bulbs and plants with soil attached. Emerging in April and May, the adult beetles lay their eggs on the undersides of leaves from about late April until early September. Eggs hatch in about a week and the larvae feed on both foliage and flowers from May through September. In two weeks, when the larvae are fully grown, they pupate underground and emerge as adults for another cycle of feeding, then return to the soil or nearby ground litter for overwintering. Click Red Lily Beetle for photo and general information from wikipedia.

The adult beetle has reported to have been found on Hosta, Lily of the Valley and Soloman's Seal. In North America, reports of Lilioceris lilii were first discovered in Montreal, Quebec in 1943 and the beetle has now spread into the New England States. The first reports in the USA were in the Boston, Massachusetts area. The USDA has theorized the beetle came in from Montreal with contaminated or non-sterile soil in potted plants that might have not been thoroughly inspected before entry into the United States. Article by Crystal Ernst, B.Sc., M.Sc.

Lilioceris lilii has been making it's way westward through the Canadian provinces and now appears to be firmly established in Ontario, Manitoba, Saskatchewan, and even Calgary, Alberta, most likely due to inter-province delivery of plants with infected soil. In the United States, live plants are generally prohibited from being shipped westward in soil due to the destructive Japanese Red Beetle which gardeners in the eastern states have been battling for more than a century and thankfully ignores lilies. Regional delivery of potted plants in the nursery trade and sharing of non-inspected lily bulbs or contaminated soil is probably to blame, plus natural growth of the beetle. Preferring hot dry days for flight, the Red Lily Beetle's natural distribution seems to be slower in areas of wet, cold summers, faster during record breaking summer temperatures in the Northeast a few years back.

Organic controls

In spring, when lilies are beginning to emerge just a few inches out of the soil, begin looking for overwintered adult beetles, inspecting stems from all angles. Lift leaves and also carefully inspect the crowns when they are still small and before developing buds begin spreading apart. Wear disposable or dish washing gloves and put white cloth or paper under plants as you work. Hold a plastic carton of hot, soapy water under each area of the stem you are working on. If the beetles sense danger or see a shadow, they will most likely drop, dark belly side up, hopefully in the water or where you can pluck them off the light colored material. (Dropped onto mulch or soil will make it difficult to find them again, so put down your light colored mat first.)

Our most entertaining "method" of plucking beetles off stems and leaves was shared by a customer several years ago. He told me the neighbors looked at him very strangely for a few mornings until he explained what was going on, but his collection method was quick and easy.

He explained that each morning after the dew dried his routine would be to wander out into the lily garden with a cup of coffee in one hand, and a cordless hand vacuum in the other, and would simply "suck them up" before they knew he was there. This was over the phone and I was laughing so hard with the mental picture that I didn't inquire much further, but I believe he then quickly knocked the beetles out of the dust cup and into a container of alcohol or soapy water for disposal. He did recommend using a hand vac with a disposable bag. I'd imagine that this would be somewhat like using the vacuum to catch house flies in the window sill, so if it works for you too, please share your "technique" with us.

An application of Diatomaceous Earth spread around the base of stems that might have been affected the previous summer will not only impact the adult beetles, but also help to eliminate unwary mollusks who might dine on the lily sprouts as they emerge, a double benefit. You can also lightly mist lily plants throughout summer and sprinkle the fine Diatomaceous Earth powder on the leaves. Use a puff applicator for under leaves. An empty mustard or honey bottle works just fine and promotes recycling, but a purchased "Insecticide Dust Applicator" for under $15 will probably be easier and more accurate. Heavy rain or overhead sprinkling will wash off the powder, but if you can see this method is working for you, be sure to reapply it on a regular schedule. Do wear a dust mask while working with Diatomaceous Earth, your lungs will appreciate the consideration.

Browsing the web, I've found suggestions for everything from strong-brewed coffee, cider vinegar or lemon juice mixed with liquid dish washing soap or Horticultural Oil (Spreader-Sticker) sprayed on the foliage as a repellent. Although some may take issue with the effectiveness of common household ingredients, an article on the Royal Horticultural Society's website seems to suggest that this avenue of control might be in the future, as studies seem to indicate that the beetles are drawn to the host plant and other colonies of beetles via scent. Perhaps beetle control in the future might involve masking the scent, thereby confusing the beetles.

More aggressive measures

The use of Bio-neem and Neem Oil is recommended by several of our customers. The following is from a customer who is enthusiastic about the results in his garden.


6/19/2010

"Since 1984 I have lived in coastal Duxbury, MA about half way between Boston and Cape Cod. In the mid '90s the local news alerted us to the red lily leaf beetle -- it had just shown up in Hingham, MA, a mere 20 miles from my home. No one knew what to do about this pest, though the spread was expected to proceed slowly. The beetle was described as a looking similar to a ladybug only smaller and solid red. This was horrific news for me, since lilies were my favorite garden plant then and practically nothing could be done about the beetle.

It actually took the beetle 4 years to wend its way from Hingham 20 miles down the coast to Duxbury. That was longer than I had expected. I finally saw the first beetle in 1999. Then a year later the beetles arrived in force and devoured all my lilies. They hit in late May and ate for about two weeks. No leaves were left, so no flowers, and smaller stalks would come up the next spring. Regretfully I began concentrating on dahlias instead -- very successful with those, but there's more work digging, etc.

With the lily beetle's arrival each May thereafter, the lily damage always came early in the season. So there was not time for the foliage to replenish and expand the parent bulb. Within three years all my lilies were gone except for one variety [a Tetraploid "Tiger" no longer in commercial production].

Though surviving from year to year, even this tetraploid Tiger has had too little foliated time to bloom, and barely enough time for the foliage to even maintain the bulb. The beetles always arrive on time, and that's it. Nonetheless my dozen tetraploid tigers have survived for a decade flowerless as such. All the other varieties, about 80 bulbs, died about ten years ago when the beetles arrived. All this is why I had stopped ordering lily bulbs long ago.

Finally this year I declared war on the beetle, not expecting success. However, it turns out there is an entirely safe insecticide/repellent, Neem, which is also very effective. On the lilies Neem does best with close inspection and thorough application to each plant. So a hand sprayer is best. A large area with a hundred lily plants or more might be a chore. Two or three dozen plants would not be a chore at all.

This year as soon as the beetles began arriving I sprayed Neem by hand -- this was around May 20th. I aimed above and below the leaves and was careful to generously drench. I also sprayed the soil near the base of each plant The beetles quickly got disoriented, slid down the plant and wallowed around in distress for awhile on the ground. I avoided picking off the beetles by hand in order to see what the spray would do on its own. I checked again twice a day for the following few days, to be sure. The beetle population was drastically reduced after even the first Neem application, and there was very little subsequent damage. Each day a reduced follow up spritz got rid of the few beetles which had just recently arrived. After about ten days or so the beetles were essentially gone (the cycle timed out, I think) and with minimal damage to my lilies. Since June 5th I have seen only two beetles among my dozen plants and no additional damage. Neem has a repellent characteristic which is as important as the insecticide, and the lily beetles seem to hate it. This year there are flower buds on my survivors for the first time in ten years, and plenty of foliage will remain for the rest of the summer. Without Neem in past years the foliage had been all gone by about June 1st.

I found Neem maintains its effectiveness for a day or so even after a rainstorm, perhaps because I had drenched the leaves generously. But I would still repeat the treatment just to be sure. There is some residual protection, but I would not press that beyond two or three days (even without rain) when beetles are in the neighborhood... I find the Neem concentrate is most economical at about a tablespoon per gallon of water. A pint of concentrate is around $16 or $17, so it goes a long way. With the concentrate I think it's best to prepare a new mixture in the necessary size batch rather than mixing a lot more and letting it sit for days. It goes in the hand held size sprayer or even the big two gallon size which you have to pump-pressurize. For lilies and beetles, use the hand held and watch closely and thoroughly what you're doing. The big sprayer would be for much larger mass applications and for other pests -- entire vegetable garden, etc. The premixed Neem hand sprayers are expensive, so I don't use them. Concentrate is much cheaper. Mix it yourself.

With some success at hand, finally, I plan to plant some more lilies this fall."


6/27/2010

"Hi, again, here's a beetle update.

Yesterday I noticed another wave of the lily beetles after almost three beetle-less weeks. It was far fewer beetles this time, only 5 or 6, and there was no damage since I caught them early. They showed up all at once yesterday afternoon. I had been been watching all along checking my plants twice a day or so. I had stopped spraying about two weeks ago and just watched, and no lily beetles appeared until yesterday. So I sprayed then and again today. I haven't seen any more.

I also found my first Japanese beetles and sprayed Neem on them. It doesn't seem as effective on those as with the lily beetle. The Japanese types don't seem interested in the lilies fortunately.

So it seems these lily beetles can regroup after awhile, the next generation perhaps. Gotta keep an eye out.

I'll let you know more if I see them again. For the next week or so I think I'll spray every couple of days and after it rains just to be sure. Then I'll pause, and see.


From the University of Rhode Island

Work on control of the Red Lily Beetle is ongoing and parasitic wasps has been released in some areas. Their recommendation for chemical control is as follows:

“The insecticides carbaryl (Sevin) and malathion are effective on adults and larvae. However, carbaryl is highly toxic to bees and malathion is also toxic to many non-target insects. To date, our material of choice for treating flowers is neem, an insecticide based upon extracts from the neem tree. Neem can be purchased at garden centers under the trade names Turplcx, Azatin EC, Margosan-0, Align and BioNeem. Neem kills larvae and repels adults. Neem is most effective on first instar larvae; it must be applied every five to seven days after egg hatch. The insecticide imidacloprid also provides effective control. It is available in several formulations from Bayer including foliar sprays, soil drenches, and fertilizer stakes.” Read the entire article, including the report on parasitic wasps.

The bottom line

Control is possible and only involves more awareness on your part. Some areas of the Northeast have even reported a drop in populations of beetles, possibly due to the test introduction of parasitic wasps by the University of Rhode Island, the application of controls as suggested above and/or a shift in weather, which has slowed growth.

If you are in a region known to harbor Lilioceris lilii, start your attack now, do not wait until spring. Start with controls that have the least amount of impact on the environment, hand-picking and Diatomaceous Earth, plus BioNeem if you so choose.

Avoid transplanting any bulbs or plants to another area of your garden with soil if you suspect the Red Lily Beetle may be present. Wash off soil "in place" and examine and treat any bulbs with a commercial pesticide, especially if sharing with a friend. Remember that most areas of the US do not have this pest and also that "Knowledge is power".
Sir Francis Bacon Meditationes Sacrae c 1597.

©2010 Dianna L. Gibson, all rights reserved.


Wild Lilies
Timely Tips!
Wild Lily bulbs making up the genus Lilium belong to the family Liliaceae comprising of approximately 200 genera made up of approximately 2,000 lily species. There are in the neighborhood of 110 to 120 Lilium species depending on whose classification you reference. For the full article, click Knowledge Base