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Catch up: Gypsy Moths - what should we do?

Monday December 14, 2020

From 2020 Aug 17: 
European Gypsy Moths are back … after the last invasion about 25 years ago. 
Round Lake and Kosh Lake have been hit particularly hard.  Some have heard the caterpillars munching at night!  One saw oak trees at a friend’s place on the bay with just the centre spine of the leaves left on the branches!  Sad times. 
Techniques to get rid of Gypsy Moths can include simple mechanical solutions, or the ultimate sledgehammer, pesticides. 
An Entomologist familiar with our area and having done research on these infestations has examined the question of whether we should spray pesticides or not. 
These chemicals are often highly toxic as carcinogens and endocrine disruptors, and attack the central nervous system of many animals including humans. 
Pesticides also bio-accumulate in food chains.  In other words, spraying enough to kill Gypsy Moths will kill many other beneficial insects like butterflies, and will affect the birds and frogs that eat them, as would fish and other predators including loons. 
So, instead of having the problem once every 20+ years, you will have it every year. 
In Canada and USA we almost killed the Eagle and the Osprey, but finally now they are increasing in number.  We still don't have Nighthawks anymore; they used to be common.  Same with Whippoorwills.  This is likely from pesticides used elsewhere – long range transport of pesticides is a real thing too. 
On a neighbouring lake, their association sprayed in 1987 and it worked well but it also killed crayfish, pollinators of all sorts, and insects including dragonflies.  It took quite a few years for things to normalize again. 
Bottom line re pesticides: not good. 
Physical/Manual Methods
For more-immediate remedies, local Kosh Lakers down the road recommend vacuuming them up with a vacuum cleaner, or squishing them. 
Other more robust mechanical techniques include:

  • Keep your trees healthy and better able to ward off attacks.  In urban areas, water trees during dry spells and protect their root zone.  In natural areas, good forestry practices will ensure healthier trees that are better able to withstand stresses such as defoliation.  Remove debris that may shelter gypsy moth larvae.  Most trees recover most of the time.
  •  Natural predators also help to control gypsy moth populations, such as birds, spiders, beetles, flies, and wasps.
(Image: brown male and white female Gypsy Moths, with tan egg mass below)
  • A band of either burlap or other cloth product wrapped around the trunk of a tree will provide a place for caterpillars to hide during the heat of the day.  Check these bands regularly and scrape caterpillars into a container of soapy water (or feed them to the fish - the bass seem to like them)
(Image: Gypsy Moth caterpillars)
  • Their egg masses can contain between 600 and 1,000 eggs.  An egg mass can be as large as a 50 cent piece, is usually oval and flat, and has a felt-like texture. They are found in sheltered locations, such as under tree limbs, tree trunks, tree wounds, corners around windows and doors, house eaves, gutters, fences, and woodpiles.  The egg sacks can be seen all winter but they won't hatch until spring.  Egg masses can be easily controlled by removing and burning or soaking with soap and water mixture.  This is our big opportunity as Fall approaches.
(Image: white female Gypsy Moth with egg mass)

Post-Invasion Footnote
Already here in August, it looks like most of the deciduous trees on Hwy 28 up to Apsley, that seemingly were stripped bare by the Gypsy Moth, are now coming back to life and growing leaves again.  Nature often heals itself, but keeping your trees healthy, catching caterpillars, and destroying egg masses between now and springtime can help reduce the big problem that could likely come next year.
Good reference:www.invadingspecies.com/gypsy-moth

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