As spring approaches, unfortunately it is time to think about lily beetles, which will emerge from hibernation about the time that lily noses are starting to poke through. The beetle hibernates in the soil or under leaf litter. It may hibernate near lilies, but also may hibernate anywhere in the garden.
Coffee grounds sprinkled around the lily noses first thing in spring seems to be a somewhat effective deterrent. Gardeners have also used diatomaceous earth sprinkled early in spring, with reasonable good results. Timing is important for the use of diatomaceous earth, as once the beetles emerge and fly away, it will have no effect on them. Neem oil has also been used with some success, when applied to plants during the growing season.
Some gardeners in Manitoba, who have already been dealing with this pest for a few years, have had some success with sprinkling Sevin or Rotenone around the noses of emerging lily bulbs early in spring. This has been effective in killing the lily beetle as it emerges in spring to feed and mate.
Safer’s End-All spray has also been found to be somewhat effective for use later in the season. As with any pesticide, it is very important to use according to manufacturer’s instructions. It is also important to remember that many pesticides and insecticides are wide ranging in their ability to
kill insects and they will destroy beneficial insects as well as those we wish to be rid of. Please exercise caution if you choose to use pesticides / insecticides. Keep our bees and ladybugs safe!
Daily checking, hand picking and destroying of the adults and larvae remains the most environmentally friendly way to get rid of them, as well as checking the undersides of leaves and picking off and destroying the small reddish orange eggs. Hand picking the beetles can be tricky, as they will fall off the plant if they sense motion nearby.
You can report infestations to the Lily Beetle Tracking site. This site also has some information about lily beetle control.
by B. Adams-Eichendorf (CPLS Newsletter March 2018)