Post by ridge on May 16, 2021 19:40:59 GMT -5
- DNR News -
May 12, 2021
Contact: James Wieferich (DNR), 517-284-5866 or Mike Philip (MDARD), 517-512-0187
Gypsy moth activity expected across Lower Michigan
The caterpillars have spiky hairs and a pattern of red and blue dots.
Following defoliation by gypsy moth caterpillars last year across much of the northern Lower Peninsula, Michigan residents across the state may start to notice the loss of leaves on oak, aspen and maple trees again this year.
Gypsy moths are an invasive species, a term for non-native pests that can cause harm to native species and ecosystems. In its caterpillar life stage, the insect is a voracious leaf eater. Large numbers of gypsy moth caterpillars caused widespread defoliation in the state from the mid-1980s to the early 1990s. A large population in 2020 may lead to more caterpillars hatching this spring in localized areas across Lower Michigan.
Last year, defoliation was heaviest in Alcona, Alpena, Montmorency and Oscoda counties, with more localized outbreaks from Manistee south into Newaygo County. Department of Natural Resources forest health experts say it is likely that gypsy moth caterpillar populations will crash in some areas while they thrive in others. Heavy defoliation likely will become visible within the next month in localized outbreak areas and persist through mid-July.
“Gypsy moth caterpillars rarely kill trees in Michigan,” said James Wieferich, DNR forest health specialist. “Only stressed trees suffering from problems like drought, old age or root damage are at high risk. In most cases, gypsy moth caterpillars are more of a nuisance in residential areas on houses and in yards than in the woods.”
The leaf-eating caterpillars are hairy, up to 2 inches long and have a pattern of blue and dark-red spots. Male moths are dark buff in color and fly; females are white with black, wavy markings and do not fly.
Keep trees healthy to help them rebound, seek licensed pesticide applicator businesses familiar with the complex pesticide laws, including notification and permitting requirements.
A list of Michigan businesses licensed to apply pesticides is available at Michigan.gov/MDARDPABL. Additional information about pesticide laws and regulations is available at Michigan.gov/MDARDPestCert.
To address a gypsy moth infestation in a handful of individual trees, homeowners can purchase a spray containing Bacillus thuringiensis var. kurstaki, a bacterium that naturally occurs in the soil but can be lethal to certain caterpillars and moths. The best time to spray is when caterpillars are small, usually mid-May through early June. If you decide to apply pesticides on you own property, be sure to choose an EPA-registered pesticide and apply it according to label directions.
Caterpillars move up and down trees, often massing on tree trunks. During this time, spraying caterpillars with a mixture of dish soap and water or scraping caterpillars into a bucket of soap and water also can be effective.
To learn more about gypsy moth caterpillars, visit the MSU Extension website. More detailed information is available in this MSUE bulletin that covers the Btk management for gypsy moth.
For more information about the DNR’s Forest Health Program or to view last year’s Forest Health Highlights report, visit Michigan.gov/ForestHealth.