Calling All (Lily Beetle) Dung
URI RESEARCHERS LOOKING FOR NON-PESTICIDE APPROACHES TO SAVING LILIES
Off the lawn topic today, but very much on the pesticide topic . . .
Lilies have long been one of the more spectacular go-to easy flowers for gardeners the world over. In recent years, though, the plants in the Northeast have been devastated by a spectacularly beautiful insect known as the lily leaf beetle.
Looking at first glance like a scarlet red cousin of the lady bug, the lily leaf beetle soon becomes an excrement-covered nightmare — with your devoured lilies in its wake.
If you grow lilies in New York and New England, and have lily leaf beetles feeding on them, the University of Rhode Island would like your help. More specifically, they want your, er, lily beetle dung.
“The University of Rhode Island (URI) Biological Control Lab is researching natural enemies of the lily leaf beetle,” reads a release that’s getting wide circulation in the Northeast. “Small parasitic insects were established in lily plots in Cumberland, RI, and Wellesley, MA., and other locations in New Hampshire and Maine. URI researchers hope that the insects will disperse naturally from these release sites, eventually reducing problems with the lily leaf beetle throughout New England.”
When the lily beetle reaches the larval phase of its lifecycle, it begins to cover itself in its own excrement. URI is asking you to collect the larvae — and the excrement — and pop it the mail to researcher Lisa Tewksbury.
Here are the mailing instructions: Please put about 20 of the largest larvae you can find (preferably fourth instars, see photo), some lily leaves and a piece of paper towel into a rigid container with a lid. Please do not add any water; the lily leaves will provide some moisture. Two suggestions for good sturdy containers are cottage cheese or yogurt containers. Label the lid with your name, complete address, and the date that you collected the larvae. Include an email address if you have one. Please tape container closed so that the larvae don’t escape! Then mail the package to Lisa Tewksbury, Dept. of Plant Sciences, 9 E. Alumni Ave. Suite 7, University of Rhode Island, Kingston, RI 02881. And if you’ve got questions about the whole process, call Lisa at 401p874-2750 or email email@example.com.
NOW, AS FAR AS CONTROL OF THE BEETLES GOES . . .
It’s going to be a while to determine if these parasitic insects are really working and, in the meantime, many gardeners have sadly given up growing lilies. Even more concerning are the gardeners who still grow lilies, but maintain them by spraying some of the most toxic synthetic pesticides we still have on the market today.
The insecticides carbaryl (Sevin), malathion and imidacloprid are most often recommended. However, carbaryl is highly toxic to bees and malathion is also toxic to many non-target insects. Imadacloprid is within the class of pesticides known as neonicotinoids, which are responsible for Colony Collapse Disorder in bees.
If you just grow a few lilies, then picking the beetles by hand is actually a practical, simple solution. If you grow more than a few, or just don’t like touching bugs, then the best recommendation is neem. The product has typically been sold in an oil formulation, but two years ago Azasol — a water-soluble powdered version — hit the market. It’s more effective and a better bang for your buck.
BACKGROUND FROM URI
Lily leaf beetles will taste or feed lightly on many plants including Lilium spp., Fritillaria spp., Polygonatum spp. (Solomon’s seal), Solanum dulcamara (bittersweet nightshade), S. tuberosum (potato), Smilax spp., Nicotiana spp. and other plants. However, they will only lay eggs and develop on Liliuim species (Turk’s cap lilies, tiger lilies, Easter lilies, Asiatic and Oriental lilies), and species of Fritillaria.
The lily leaf beetle adult is a striking insect with a bright scarlet body and black legs, head, antennae, and undersurface. The adults are 6 to 9 mm (1/4 to 3/8 inch) long, and they will squeak if they are squeezed gently–a defense mechanism to deter predators. Adults and older larvae feed on leaves, stems, buds, and flowers of the host plant. Adults lay their eggs on the underside of leaves in an irregular line. The reddish/orange eggs take from 7-10 days to hatch under normal conditions. Females lay up to 450 eggs, sometimes over two growing seasons. Larvae resemble slugs with swollen orange, brown, yellowish or even greenish bodies and black heads. Larvae tend to cause more damage than adults. Larvae are distinctive and repulsive in that they secrete and carry their excrement on their backs. Younger larvae feed for 16-24 days, primarily on the underside of leaves. Larvae enter the soil to pupate; pupae are florescent orange. New adults emerge in 16-22 days and feed until fall. They do not mate or lay eggs until they emerge the following spring in late March through June. Lily leaf beetles overwinter in the soil or plant debris in the garden or woods, sometimes a distance away from the host plants. Adults prefer environments that are shaded, protected, cool, and moist.