Lilies come back every year if you plant them in the open ground. That is of course very nice when you discover that they start to grow again from the bulb in the spring. But besides you, these shiny red creatures may have also discovered that a new lily is growing there. Scarlet lily beetles (Lilioceris lilii) are herbivorous insects that have lilies and fritillarias on top of their menu, and last week I suddenly discovered a bunch of them on those Fritillaria’s.
Scarlet lily beetles are native to Europe, and where introduced in America around 1945, probably with imported lily-bulbs. Unlike in America, the Scarlet lily beetle has some natural enemies here, and a parasitary wasp (Diaparsis jucunda) that lays here eggs in the larvae, is the most important.
The insects know very well how to the defend against birds: the adult are said to taste very bad, and the larvae use their own frass to make a protective shield, that makes them look like a walking bit of bird’s droppings… and no bird wants to taste it! (However, this ‘shield’ helps the parasitay wasps to locate them….)
If you discover a lily beetle in your lilies, you must ensure that you kill them as quickly as possible. But be careful…. Scarlet lily beetle are easy to scare, and by the slightest threat, they let themselves fall to the ground. Therefore, ask for some help if you discover them too late and there are already several in there. Place your hands under the plant and then tap the bottom of the stem. Another idea is to place a cloth around the stem for them to fall on.
If you want to prevent lily beetles from getting into your lily, the best way is with chemical insecticides. These must be controlled early in the season (April-May) to prevent lily beetles from appearing. For biological control, you can use soapy water (preferably brown soap) or neem oil, which may help to smooth the leaves, preventing the lily beetles from remaining on the plant. You will have to repeat this treatment often! There is also a mild but effective organic alternative: an extract of sage and oak bark. This mixture is simply sprayed on the plants and the Roosters disappear because they no longer recognize the lily as a lily. The plant absorbs the essential oils of sage and oak, masking the lily scent, which is irresistible to roosters. Apply again if roosters are spotted again.
Sage oak extract (for 1 liter)
Cut 100 grams of real Sage (Salvia officinale) into small pieces and add 1 liter of water. Take two long twigs from an oak tree and remove the skin from them. Add the peel to the water with the sage. Boil gently for 1/2 hour. Drain and collect the preparation. Spray your Lilies, Imperial Crowns and Kiviets flowers with this. The Lily Beetles will ignore the plants. Repeat the procedure if Roosters are spotted again.