Numbers are on the rise again for an invasive insect feeding on Minnesota's trees. The Minnesota Department of Agriculture (MDA) captured approximately 1,049 gypsy moths this year in traps around the state. That's up from last year's 523 moths but still a major shift from a 2013 count of more than 71,000 moths.
Researchers say the 2014 population drop reflected a severe winter, especially in Northern Minnesota. However, predictions of a warmer-than-average winter this coming season bring concerns that gypsy moth numbers could once again surge.
"One surviving female gypsy moth can lay an egg mass that will produce more than 500 hungry caterpillars the next year," said Kimberly Thielen Cremers, MDA's Gypsy Moth Program supervisor.
Fluctuating insect populations are not uncommon. Since 2002, MDA trapping data shows gypsy moth numbers have swung up and down across the state.
"Populations often take some time to rebound after drastic crashes such as the one caused by the winter of 2013-14," said Dr. Brian Aukema of the forest insect laboratory at the University of Minnesota. "But while moth populations may be knocked down, they are not knocked out."
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State and federal officials implemented a quarantine of gypsy moths in 2014 for Lake and Cook counties after data showed a reproducing population had established itself in the area.
Gypsy moth caterpillars, which are not native to North America, eat the leaves of many trees and shrubs. Severe, repeated infestations can kill trees, especially when the trees are already stressed by drought or other factors.
For more information on gypsy moths, go to www.mda.state.mn.us/gypsymoth .
