How do I keep the red lily leaf beetle from destroying my lilies?
Image by: Wendy Richardson
Adult Red Lily Leaf Beetle
ORIGIN: The red lily leaf beetle (Lilioceris lilii) is an insect native to Europe and Asia which rapidly spread through New England from Eastern Massachusetts and which has been also been found in Northern New York State. The original infestation in New England was detected in 1992 in Cambridge, Massachusetts, although the beetle has been active in the Montreal, Canada, area since 1945. There are recent reports that the beetle has been seen in Alberta, Canada, since about 2005.
DAMAGE: If uncontrolled, the beetle will completely defoliate and ultimately kill all true lilies (Lilium species, such as Asiatic, Oriental, Easter, Tiger and Turk's Cap lilies). It will also feed on Fritillaria species, and many other plants, although the primary targets are Lilium and Fritillaria species.
DESCRIPTION: The adult beetle is bright scarlet red, with black legs, head, antennae and undersurface. It is 1/4" to 3/8" long and is a strong flyer. The beetle reportedly will squeak if squeezed gently (however, few gardeners are willing to be gentle to this beetle). The adult lays reddish-orange eggs which hatch into particularly unpleasant larvae, which look like 3/8" long slugs; colored orange, brown, yellow or green with black heads. The larvae cover themselves with their own excrement (known as a fecal shield) which apparently repels predators, including gardeners who are generally very reluctant to handle the larvae. The larvae eventually become fluorescent orange pupae.
LIFE CYCLE: The adult beetle overwinters in the soil or plant debris and emerges in early spring looking for food and a mate. After mating, the female lays eggs in lines on the underside of Lilium or Fritillaria leaves. Some damage is done by the adults at this time, but the major damage comes when the eggs hatch into larvae in 7-10 days. The larvae voraciously consume all leaves within reach and may then start on flower buds. This continues for 2 to 3 weeks, when the larvae then drop into the soil and begin to pupate. In another 2 to 3 weeks the adult beetles emerge to start eating again. This process occurs from early spring to mid-summer. Reportedly the beetles won't mate and lay eggs until the next spring.
FIRST REPORTED SPRING SIGHTINGS:
2003 - April 21 in Massachusetts.
2004 - April 18 in Massachusetts.
2005 - April 9 in Massachusetts and also in south coastal Maine.
2006 - April 9 in Massachusetts.
2007 - April 19 or 20 in Malden, MA, reported by michaelb_maz6.
2007 - April 22 in Amherst, MA, reported by pattioh.
2007 - April 24 in Haverhill, MA, reported by chazparas.
2008 - April 15 in Billerica/Lowell, MA area, reported by a neighbor of littleonefb.
2008 - April 17 in Burlington, MA (heavy infestation) reported by a friend of littleonefb.
2008 - April 17 or 18 in Malden, MA, reported by michaelb_maz6.
2008 - April 19 in North Waltham, MA, reported by weedsmakemecrazy.
2008 - April 21 in Lexington, MA, reported by idabean.
2008 - April 21 in Shrewsbury, MA, reported by sunshineboy.
2008 - April 23 in CT Zone 5-6, reported by evonnestoryteller.
2008 - May 5 in Hollis, NH (southern NH) reported by wrichard.
2009 - April 15 in Lexington, MA, reported by Idabean.
2009 - April 18 in CT Zone 5-6, reported by evonnestoryteller.
2009 - April 30 in CT Zone 6, reported by diggerdee.
2009 - May 5 in Rochester, NY, reported by jgpr (first sighting there).
2009 - May 17 in Boston (proper), MA, reported by extragalactic.
2010 - April 1 (more or less) in CT Zone 6, reported by diggerdee.
2010 - April 3 in MA Zone 6 (on fritillaria), reported by marie of roumania.
2010 - April 4 in Boston, MA Zone 6b, reported by extragalactic.
2010 - April 7 in North Waltham, MA, reported by weesdmakemecrazy.
2010 - April 8 on the RI coast Zone 6, reported by tulipscarolan.
2010 - April 13 in Zone 5a (on fritillaria), reported by idabean.
2011 - April 21 at Rt 128 and the Pike, MA Zone 5, reported by pixie_lou.
2011 - April 22 in CT Zone 6, reported by lepages.
2011 - April 24 in MA Zone 6 (on lily), reported by marie of roumania.
2011 - April 25 in CT Zone 6, reported by diggerdee.
2011 - April 28 in Zone 5a (on lily and fritillaria), reported by idabean.
2011 - April 29 in CT Zone 5-6, reported by evonnestoryteller.
2011 - May 3 in Plymouth, MA Zone 6b, reported by claire.
2011 - May 21 in Webster, NY, which is a Northeastern suburb of Rochester, NY Zone 6, reported by Singzjazz.
2011 - June 22 in East Haven, CT Zone 6, reported by jenhubb.
2012 - April 3, approximately, in CT Zone 6, reported by diggerdee.
2012 - April 8, approximately, in CT Zone 6 (major infestation), reported by casey1.
2012 - April 16, approximately, in MA Zone 5, in metrowest - near 128 and the pike, reported by pixie_lou.
2012 - April 17 in Zone 5a (on stem of an Asiatic lily), reported by idabean.
2012 - April 30 in MA Zone 5b, reported by steve_mass.
2012 - May 1 in Ansonia, CT Zone 6, reported by javaandjazz.
2012 - May 6 north of Calgary, AB, Canada zone 3, second year in a row, reported by tomlvi.
2012 - June 3 in West Haven, CT Zone 6b, reported by molie.
2013 - April 17 in CT Zone 6, reported by casey1.
2013 - April 17 in CT Zone 6, reported by diggerdee.
2013 - April 17 or earlier in RI Zone 6, reported by cheleinri.
2013 - April 18 in MA Zone 6a, reported by prairiemoon2.
2013 - April 19 in Narragansett, RI, reported by elaine_2008.
2014 - ~ April 22 at Rt 128 and the Pike, MA Zone 5, reported by pixie_lou.
2014 - April 26 in CT Zone 6, reported by casey1.
2014 - around May 5 in MA, Zone 6a, reported by prairiemoon2.
2014 - May 12 in Plymouth, MA Zone 6b, reported by claire.
2014 - May 12 in Central CT, Zone 6, reported by corunum.
2014 - May 13 on CT coast, Zone 6, reported by mjc_molie.
2014 - June 12 in Troy, NY Zone 5, established infestation reported by debi1315.
2014 - June 15 in New Haven, CT Zone 6, reported by joe_267.
LAST REPORTED FALL SIGHTINGS: 2003 - mid October on the coast of New Hampshire and Massachusetts
BIOLOGICAL CONTROL: There are no known natural predators in this country, although the beetle is well under control in Europe, where at least six parasitoids attack it. Researchers at the University of Rhode Island are actively engaged in releasing parasitic wasps in this country and seem to be confident that biological control can eventually be established here as well.
COMPANION PLANTING An interesting observation was made by gardencommando concerning a possible deterrent effect of Chelone on the beetle.
"this summer we were totally infested with the red Lily Beetle. After reading up on the subject, I used the simple drowning them idea, but modified the mix a little - amonia with dish soap. Although I stalked and killed hundreds of the horrid things, I suffered heavy damage to all the lilies except 1.
The one an only difference that I could find is:
the completely undamaged lily has a Turtle head planted on each side of it. I checked on the toxity of Chelone and although it seems to not be edible it says nothing about repelling pests.
The untouched lily was planted less than five feet away from ones that were attacked. The turtle heads are roughly 1 foot away from the Lily. I just thought it might be of interest to everyone, and might possibly work out to be a good companion plant."
"Very interesting observation! Time to do some experimenting/testing. The obvious first experiment is to interplant Chelone closely with lilies. Everyone in the range of lily beetles certainly can easily experiment with this one as it sprouts easily from seed."
ACTIVE CONTROL: First of all, if you're in an infested area, avoid sending any lilies or other plants to anyone else, and carefully inspect any plants you receive.
Hand-picking should be the first level of control if possible. Constant vigilance and quick removal and disposal of beetles, eggs and larvae can control an infestation on a small number of plants. Make sure the critters are actually dead! If you squash them, don't leave the squashee in the garden. Some gardeners drop them into a can of water with vegetable oil on the top.
If you suspect the beetles may be lurking around your lilies but you don't see any, carefully dig in the top half inch of the soil - no deeper! They hide just under the surface, so be ready to get them when they pop out.
Roxanna reports the following tip: "I recently read somewhere what seems to be a good tip, and pass it along to you in case you want to include it in your FAQ info: the adults are easily spooked when you try to pick them by hand, and if you "miss" them, they tend to drop to the ground where THEY LAND UPSIDE DOWN, and since their tummies are black, they effectively vanish. The suggestion was to place a light-colored cloth under the plant before you hand-pick in order to be able to see the nasty little things if they fall."
If this isn't feasible, then treatment with Neem is the next choice. Neem will repel beetles and kill young larvae, but must be applied every 5 to 7 days after the eggs hatch.
Merit (imidacloprid) is a systemic insecticide which may work if applied to the soil in early spring. Many New England gardeners are also reporting good results from the use of products containing imidacloprid when applied later in the season. Bayer manufactures several products containing systemic insecticides, both in spray and in granular form.
The Bayer Rose and Flower Spray has provided excellent control for many gardeners, without serious toxicity issues. However, it's important to follow the label directions to prevent destruction of bees and other beneficial insects while the spray is drying. The general principle is to apply the product when beneficial insects are not around, and to let it dry. This is probably a good idea with any insecticide since they are not specifically targeted to one insect species.
Other chemicals of relatively low toxicity include the following:
*10% household ammonia, applied to the newly emerging lily sprouts and surrounding soil (reported by northerner on of Ontario, Canada).
*Pyrethroid insecticides (Permethrin is one) kill adult beetles (reported by the UMass Extension).
*Spinosad insecticides kill larvae (reported by the UMass Extension).
More powerful chemical insecticides can be used, but are inherently dangerous to humans and to beneficial insects and should be used with extreme caution. Carbaryl (Sevin) and malathion are effective on both the adult beetles and the larvae.
There's also been one recent report in New England that Bantam chickens love to eat the beetles! Unfortunately, they don't seem to consider the disgusting larvae to be food, but eating the adults should make a dent in the population.