Below is an update on the Gypsy Moth infestation here in Sturbrigde from our Tree Warden, Tom Chamberland.
Leon A. Gaumond Jr.
Town Administrator
Gypsy Moth update: There have been a few questions regarding the current stage of the gypsy moth infestation. I have tried to answer a few of them:
Why are the caterpillars in various stages of growth, from ready to pupate to moths, to just about 1’ long?
Every yard has it's own "microclimate” think of South exposure to sun vs North exposure, no sun. gypsy moth egg masses that were laid on "south" exposures or warmer micro climates, experienced more and sooner warmer days than those on the "north" side, or under rocks/logs etc. Thus, the actual "ballooning" (the proper word for hatching of gypsy moth eggs) took over a 4-week period. So, the final pupal stage/moth will likewise be about 4 weeks long.
This extended ballooning period is why proper timing of application of various pesticides was so important to getting a good "kill"
At least in my neighborhood (very south section of Sturbridge) I have not seen a living caterpillar in over 24 hours! We are at a higher elevation; thus, the ballooning of gypsy moths was later, giving the natural bacteria and fungus more time to develop and affect good control.
Newer residential areas with their lack of mature trees, larger homes and large open lawns, and those areas of town at lower elevations (yes even 100’ will make a difference) was a warmer micro climate, thus ballooning in those warmer areas occurred earlier, and the more mature caterpillars are now less susceptible to the natural control forces.
I have dead caterpillars above my tinfoil wrapped trees?
Yes, sticky tin foil does prevent travel both ways. However, the feeding cycle is usually they will drop on their “threads” to get to the ground during the heat of the day and climb back up when cooler. Nothing however stops them from also just walking down the trees, especially on the shaded or cooler side of the tree.
Are they all dead?
Very many of them are dead, almost a complete collapse of their population, however, those eggs masses that hatched very early, are now pupating into moths,(see above answer) the Brown moths are male, and gypsy moth traps you can purchase at your local garden center or supply store will trap these male moths. The female moths will start pulpating shortly too, they are white and do not fly. So, if you observe a white moth attached to a tree or wall those are the ones to eliminate before the egg mass is laid. As mentioned above, certain sections of town are seeing very good control by both the natural bacteria and fungus but given the thousands of caterpillars, I am sure some have and will survive To “live again”
My trees are leafless, are they dead? what should I do?
There is no known absolute, but for the most part your trees are not dead, even those that did not fully leaf out this year may by in a dormant state due to both the infestation last year and drought. Most healthy trees are resilient and given the slightly above rainfall, IF this continues, will bode well for our trees to recover. You can expect most trees will in three to four weeks start re-growing a new set of leaves. But do not be overly concerned if that does not happen. In either case watering is the best treatment now for your trees and shrubs that have been defoliated. Soak their root zones (out to dripline at least) with at least 1” of water weekly as we get into July and August. Keeping the root zone well hydrated will be the best treatment to save your plants.
Next spring will be the time to fully assess any damage done to your trees and plants. If they are dead, they will not fall or fail, or be of any significant risk for at least 3 to 5 years so there is plenty of time to react.
How do you know you are watering to 1”?
Set out a straight edged container (peanut butter jar, coffee can, etc.) in the watering area, turn on the sprinkler and monitor the time it takes for water to reach 1” deep in the container. Now you know how long to leave on your sprinkler. One deep weekly watering is better than several less than 1” watering’s in a week. The best times to water are before 8 am and after 6 pm.
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