MADISON – Small, bright orange or green boxes tied onto trees is just one of the signs that summer is approaching in Wisconsin.
The boxes are traps set by trappers hired by the Wisconsin Department of Agriculture, Trade and Consumer Protection to catch gypsy moth, an invasive pest. The Wisconsin Gypsy Moth Slow the Spread Program is preparing for the flight of the adult male gypsy moth in July. Female gypsy moths are flightless.
Trappers are setting the traps this month. The goal is to set a total of 26,365 traps in 48 western and central counties by early July. Traps are used as a method of population survey, not as a method of population control.
“Trapping tells us where the moths are and where they’re not,” said Chris Whitney, gypsy moth trapping coordinator. “It also helps us determine if an area needs aerial treatment the following year or if an egg mass survey needs to be done in the fall to better evaluate the population.”
Two different traps are used for trapping: a triangular delta trap, which looks like a small tent, and a milk carton trap, which looks like a milk carton with a roof. A delta trap can hold up to 20 moths, and a milk carton trap can hold up to 1,500 moths. The type of trap to set depends on where it is set in the state. In areas where gypsy moths are known to be found, most traps are the milk carton traps. Delta traps are usually set in the western third of the state where gypsy moths are not as common. There is no trapping in the eastern part of the state because it is considered generally infested, and trapping does not provide any usable data.
The traps attract male gypsy moths by using the pheromone of the female moths as a lure. The pheromone is undetectable to other insects. The traps will stay in place until the moths stop flying in August.
“It’s important to leave the traps up during moth flight to get the data we need. Then, when the moth flight ends, we’ll take them down,” Whitney said.
If a trap needs to be set on private property and the owner is present, trappers will ask the owner for permission to set the trap on the property. Trappers will wear fluorescent vests and carry an identification card. If the owner is unavailable, trappers will set the trap, and leave an information sheet and a phone number to call for more information.
“Most landowners are very cooperative, and we appreciate that,” Whitney said. “But, if a landowner wants a trap moved or removed, they can call the number listed on the trap and we can move the trap.”
The gypsy moth in its caterpillar stage is known to defoliate many species of trees and shrubs, especially oaks. Approximately 347,000 acres of Wisconsin forests were defoliated by gypsy moth last year.
For more information, call the toll-free number 1-800-642-6684, visit the website gypsymoth.wi.gov, or e-mail firstname.lastname@example.org. People also can follow the program on Twitter at twitter.com/WIGypsyMoth.
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