Gardeners on red alert as destructive lily beetle expands its foothold in Edmonton
The red lily beetle has been expanding its territory in Edmonton and unhappy gardeners are finding the result in their shredded flower beds.
"They absolutely love lilies and they will chew them right down to the ground level quickly," said Jim Hole, horticulturist and owner of Hole's Greenhouses in St. Albert.
The insects will only eat native lily and less-common fritillaria species, another bulb-based flowering plant, he said Monday.
Hole said he's been watching the insects progress from Edmonton's north end to the south side since they first arrived in the city about five years ago.
While the beetles can fly, they tend to be spread as plants are shared, clinging to the soil that accompanies the plant, he added.
The red beetle is an introduced species that has no natural predators and an interesting but messy defence mechanism, Hole said.
"They will secrete, or excrete I guess, the fecal material from in their bodies to the surface of their bodies to be a deterrent to their predators," Hole said. "It just makes them look pretty grotesque and it's pretty effective."
Cold temperatures will not kill off the beetles, which go into a dormant state and tunnel down into the soil to overwinter, he said.
With no easy solution to getting rid of the pests, it becomes more a matter of controlling them, Hole said.
He suggests regularly picking the beetles off the leaves of infected plants and destroying them.
He also suggests regular spraying of an insecticide that contains a combination of soap and pyrethrins, a pesticide that occurs naturally in some chrysanthemum plants.
The beetles sometimes make a "screeching sound" when they are picked up. Hole says that is simply the sound of them rubbing their hind legs together.
Hole has never heard of anyone being bitten by them but said gloves are still a good idea for dealing with the "messy larvae.
"Normally the larva resides on the underside of the leaves and it's coated in poop."
