Hopefully you haven’t seen a very bright red beetle in your garden eating the leaves of the plants belonging of the lily family. The scarlet lily leaf beetle is an insect native to Europe and Asia and is believed to have come to North America in the soil of potted plants. Reportedly, it has been found in the Montreal area since the 1940’s but it has made its way westerly across Canada and can now be found in all provinces west of Quebec has now been found in Northwestern Ontario, including some gardens in the Thunder Bay area. The beetle will completely defoliate and ultimately kill all true lilies from the Lilium and Fritillaria species.
The adult beetle is bright scarlet red, with black legs, head, antennae and undersurface. It is 1/2 to 1.5 centimetres long and is a strong flyer. The adult lays reddish-orange eggs which hatch into particularly unpleasant larvae, which look like 1.5 centimetre 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.
To prevent severe damage, it’s important to curb the insect’s reproductive cycle early in the season, so examine your lilies carefully several times a week, beginning as soon as the plants emerge from the ground. The adult beetle overwinters in the soil or plant debris and emerges in early spring looking for food and a mate. They will begin laying their eggs early in the growing season, often starting on spring-blooming Fritillaria that emerge around the same time as the daffodils. Most damage occurs when the eggs hatch into larvae in seven to ten days. The larvae voraciously consume all leaves within reach and may then start on flower buds. This continues for two to three weeks, when the larvae then drop into the soil and begin to pupate. In another two to three 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 again until the next spring.
The recommended method of control is handpicking which should be the first level of control. 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 them in the garden. If you suspect the beetles may be damaging your lilies but you don’t see any, carefully dig in the top half inch of the soil as they hide just under the surface, so be ready to get them when they pop out. Remember if you’re in an infested area, avoid sending any lilies or other plants to anyone else, and carefully inspect any plants you receive.
Hopefully, if you have lilies in your garden, you don’t have the scarlet lily beetle as well. If you do, you now know what these pests are and how to control them.
