Hi Charlene
Your best defense is to get to know your enemy. Hang in and read on. There is help on the way.
Lily beetle life cycle The adults overwinter in the soil or on leaf debris and can appear from mid April if the weather is warm. After mating, the female lays 200-300 orange eggs on suitable plants. About a week later, they hatch into reddish-brown larvae that cover themselves with their own black, slimy excrement. When the grubs are mature they burrow into the soil to pupate, emerging as adults in mid to late summer.
Which plants do lily beetles attack? Adults and larvae eat the leaves, flowers and seed pods of the lily and fritillary families and can do severe damage. Adult beetles nibble irregular holes in the leaves and petals, while the larvae methodically work their way from the leaf tips towards the stem. Adults are occasionally found on other plants but these plants do not seem to be eaten by the larvae.
Could I confuse them with anything else? Cardinal beetles are also bright red, with black legs, head and undersides. However, they are twice as big as lily beetles and the body tapers towards the head. Cardinal beetles are carnivorous, and found hunting other insects on a wide range of plants, especially tree trunks. Some soldier beetles are reddish brown, and the same colour underneath. They tend to favour flat, open flowerheads such as umbellifers and are often seen in mating pairs. They are also carnivorous. Asparagus beetles, to which they are related are similarly shaped but not the brilliant scarlet.
Where does lily beetle come from? It originated in the Mediterranean region, though it also occurs in China and northern India. .How far has it spread? Here in North America it is primarily in eastern provinces and states. It ranks seventh most serious insect pest in the USA .In France it is kept in balance by several parasitoids.
Why has it become more widespread recently? They have no enemies here. Lily beetles thrive in areas with warm, dry climates. Their spread may be due to our recent hot dry summers. Observers have noticed that it is reluctant to fly, except on hot, sunny days, so the warm summers of recent years have encouraged it to move further afield. This may also explain why it is spreading much more slowly through the wetter areas.
How can I control lily beetle?If you grow only a few lilies, it's feasible to control lily beetle by inspecting them regularly. Pick off and squash the adults, grubs and eggs; the earlier you start looking, the more likely you are to break the pest's life cycle. Keep the lily beetle under control, at least until the plants finish flowering, to allow the bulbs to build up enough to form next year's flowers. Where plants have been badly damaged, feed the remaining leaves with foliar feed. Reduce the stress on your lilies by mulching them and dividing regularly Plant a trap crop of Fritillarias. The early emerging adult lily beetles will be attracted to the fritts . to eat and rowdily revel. In the cool spring air they do not move very fast and can easily be dispatched in various multiples.
Are there any suitable sprays? If you have a lot of lilies and wish to use a spray, some gardeners use Neem oil. When plants are in flower, spray at dusk to reduce harming bees.
What about biological control? The lily beetle's warning red colour implies it is unpalatable to potential predators such as birds. However, scientists from the University of Rhode Island, USA, motivated by the recent arrival of the pest in Boston, are testing parasitic larvae from France on lily beetle grubs . It is hoped they may prove to be a safe, effective biological control here, not just to protect our garden lilies Our ravishing native lilies need protection from this ravaging pest.
