August 21, 2019

Browntail moths in mid-coast Maine: How to protect your hives during a pesticide spray

Euproctis chrysorrhoea Female

In 2016, the browntail moth (BTM) wreaked havoc in mid-coast Maine defoliating trees and causing respiratory problems for people. It was a particularly bad year for the invasive species and 2017 is expected to be yet another. The pest has caused such a problem in several coastal communities that many are opting to spray pesticides to combat the growing destructive population.
The browntail moth dines on the foliage of hardwoods and shrubs including apple, oak, cherry, serviceberry, shadbush, beach plum, rosa rugosa, and bayberry. Hungry two inch larvae (caterpillars) devour leaves in April-May reducing growth and sometimes killing their host. By June, they spin cocoons and in mid-July emerge to mate. Eggs are laid on the underside of leaves and in August-September a new crop of caterpillars emerges to feast again. As cold weather approaches they form 2-5 inch silken webs constructed from a single oak leaf placed in the tips of tree branches (usually red oak or apple). Hundreds of caterpillars overwinter in these nests, emerge in spring, and begin the cycle all over again.
If there is spraying for the browntail moth this year beekeepers will need to protect their colonies. Here are some tips for what you can do:
The best option to protect your hives during a pesticide spray is to remove colonies from the targeted areas.
If this is not possible, then
Close hive entrances with a metal mesh so the bees cannot get out but can still ventilate.
Drape the hive with a loose sheet so spray does not touch the hive. Do this early in the morning on the day of the spray before bees are flying.
Add an empty deep or medium on top to give the bees space to spread out, especially if it is a fast increasing colony.
Add a top feeder with 1:1 syrup.
Provide a fresh water source under the covering, such as a Boardman feeder, to help bees cool their hive.
Make sure to provide shade during the warmest part of the day, such as with a pop-up canopy.
Remove when all risk has passed and release the bees from confinement.
Note: Always check and see what the label of the product says for reentry following a spray, if possible.
Other things you can do:
Cut BTM nests from trees. If they are too high in a tree contact a licensed arborist. Burn nests or submerge them in soapy water. (Browntail moth nests differ from tent moth nests which are longer, around two feet, and located at the ‘Y’ of tree branches.)
Communicate with local officials and neighbors to learn if spraying is planned for your neighborhood. Add your name to the Maine Notification Registry.

Images of BTM nests can be found on the Maine Forest Service Insect and Disaease Fact Sheet for Browntail Moths.

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