Lily leaf beetle bugs Wausau gardeners

One fiery red insect is eating Marathon County residents out of their lilies and gardens.

Known for its scarlet red coloring and black limbs, the half-inch, oblong-shaped lily leaf beetle has been attacking central Wisconsin gardeners’ lily blossoms during the spring and summer months since 2014, according to Heather Schlesser, University of Wisconsin-Extension Marathon County home horticulture adviser.

“Last year they completely destroyed all my plants that I had,” said Jenny Luedtke Trantow, a garden hobbyist and resident of Wausau’s southeast side. “They chewed the leaves off and then they started to work on the blossoms also. I know there were other people who actually completely dug out the bulbs, threw them away and replanted.”

This year the beetle, also known as the scarlet lily beetle or red lily beetle, first appeared in local gardens around mid-may, according to reports from UW-Extension. Marathon County residents who’ve taken their frustrations with the insect to locally-focused Facebook pages have shared similar reports. Gardeners and lily enthusiasts are testing out every possible solution, from hand picking to pesticides, in an effort to slow the bug invasion and save their flowers.

Researchers from New England have even introduced one of the beetle’s only natural enemies, a European wasp, to reduce the red bug’s numbers in the region. While Schlesser says there are no plans to introduce the wasp in Wisconsin, they are working aggressively to help residents of Marathon County contain the infestation.

The beetle’s method of destruction is fast and tied to its development cycle. After spending the winter burrowed in the soil or leaf litter, the adult lily leaf beetle emerges during the first days of spring to feed, mate and lay its small orange-brown eggs on blooming lilies. While adult beetles are major contributors to the flowers’ destruction, the most significant damage comes from the beetle’s larvae, which eat away at the lily foliage throughout their growing process. Eventually, these larvae detach themselves from the flower and form a cocoon in the soil to be “hatched” the following year.

The pest can cause damage to nearly every part of the flower, but generally begins by attacking the leaves.

“They do not attack the bulbs,” Schlesser said. “They only attack the things above the ground, so they’ll attack the stem, the leaves and the flowers, but they do not attack the bulbs. As long as there is enough sugar reserve to put back in the bulb during growing season, it can grow back.”

According to material published by UW-Extension back in May of 2015, the invasive insect primarily attacks “true lilies,” including Turk’s cap lilies, tiger lilies, Easter lilies, Asiatic and Oriental lilies. Canna lilies, calla lilies and daylilies will not be affected.

The full article was first published in the Wausau Daily Herald on July 13, 2016


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