The Red Menace

The red lily leaf beetle is a big problem in Winnipeg this summer. The invasive insect has no natural predators in Canada and is difficult to control. Here are some suggestions from the Manitoba Regional Lily Society:

• Handpick the adult beetles (6-8 mm ¼ inch in length) as soon as they appear on the emerging lilies.
• Spray the adults with any pyrethrum based (0.5%) insecticide or any other registered pesticide. Rotenone may also be effective.
• Destroy the egg cases on the underside of the leaves.  Eggs are in yellow/orange clusters or in irregular rows. The eggs are quite small, approximately 1 mm.
• Remove the larvae.  Can be very messy.  Use rubber gloves.
• Dust or spray with Rotenone or any pyrethrum based pesticide.
• Spray the larvae and the underside of the leaves with Neem Oil at 5-7 day intervals throughout the season.  Neem is ineffective on adults.
• Adults over winter in the surrounding soil or under plant debris.  Some adults may survive over two seasons.  Stir up the surrounding soil or the mulch in early spring and kill any emerging beetles before they have a chance to lay their eggs.
• It is up to each gardener to check their lily plantings at least weekly for signs of the beetle.  Because the beetles are strong fliers and can move around the neighborhood, inform your neighbors and help them to control this pest.

Lily beetles in a West End garden

Lily beetle larvae

Although the suggested controls include both chemical and natural  methods, no particular products have been approved for use on the red lily beetle. Gardeners should choose the method that they are comfortable with and which work best for them.