Gypsy Moth Information
The City has received several calls in the past couple of weeks with residents who believe they have gypsy moth. This page has been set up to provide residents with information on how to deal with their gypsy moth outbreak as well as when and how the DNR will provide help.
Gypsy moth populations naturally explode to very high numbers, called outbreaks, about every 10 years. During outbreaks, the caterpillars are a nuisance and can strip trees of their leaves, defoliating entire neighborhoods or forests by late June. Most healthy trees can survive one such defoliation, but trees that are weak or stressed prior to defoliation may die.
At this point, it may be too late for the DNR to do an overhead spraying to take care of the issue. However we are asking residents to submit their information to our database so if we find that an area of 20 acres or more is in infested this year, it can be scheduled to be sprayed next spring.
If you believe you have gypsy moth, here are some things you can do.
In early June, add a cloth or burlap collection band above a sticky barrier. Sticky barrier bands can be bought or made from duct tape (silver side out) which should be wrapped around the tree trunk about waist high. On thin-barked trees such as birch, place a layer of paper bags around the trunk before using the duct tape. (Never place the sticky side of the tape on the trunk directly).
Place the collection band then above the sticky barrier, about chest high. Collection bands can be made from heavy dark cloth or burlap that’s approximately 12-18 inches wide and long enough to completely wrap around the tree. Tie a piece of twine around the middle of cloth band. Fold the top half of the cloth down over the twice to cover the bottom half. Caterpillars are attracted to these “skirts” when looking for a place to hide during the day. Destroy caterpillars each afternoon by scraping them into a container of soapy water or snipping them in half.
In July, begin inspecting all outdoor surfaces in your backyard for gypsy moth pupae. The pupa is a brown shell, often attached to tree bark or other surfaces with strands of fine silk. Those in reach are easily destroyed by crushing. Crush those that are out of reach with an extendable pole or dislodge them with water from a garden hose and destroy those that fall to the ground. Female moths are an easy target to control because they cannot fly. However avoid directly touching female moths as their pheromone will get onto your skin and you will get mobbed by male moths.
There are also many insecticides available to control the gypsy moth in your backyard. When selecting a pesticide you should consider the following:
- Presence of young children or pets
- Proximity to water resources (stream, pond)
- Presence of other desirable insect species
- Nearby vegetable or fruit gardens
Most available insecticides are used by spraying them onto the trees leaves. If general exposure (through spraying) is an issue, you might consider systemic application. A systemic approach applies pesticide directly into the tree through injections or into the ground around it where it is taken up by the roots. Older trees might show less response to a systemic application than younger ones.
For a list of pesticides for gypsy moth control, visit http://gypsymoth.wi.gov and link to “Pesticide Information”.
*Note, unless your trees are relatively small – less than 12 feet tall – you will likely need to hire an arborist or certified pesticide applicator to thoroughly and safely treat your trees. You may find one through the Wisconsin Arborist Association’s website at www.waa-isa.org.
To help us prepare for a possible spraying next year, please email Kelley Woldanski with us your name, address and acreage so we can create a database for the DNR to use next year when determining areas to spray from overhead. Or call and leave the same information at the following number, 262-691-6073.