Pheromone Traps and the Gypsy Moth (E2585)

January 29, 2016

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Pheromone traps are often used to track the spread of gypsy moth populations or to find populations in new areas. Listed below are answers to some commonly asked questions about pheromone traps.

Q. What is a gypsy moth pheromone trap?

Pheromone (pronounce fer-o-mone) traps are an important tool in gypsy moth management. Pheromone traps are made of green cardboard and may be shaped like triangles or like small milk cartons. They are usually stapled to trees during the summer. Inside each trap is a small paper strip coated with the gypsy moth pheromone – the bait for the trap. The pheromone is the chemical “perfume” that female gypsy moths give off to attract male moths. The males fly into the traps and are caught. Pheromone traps will be collected later in the summer or fall, and the number of gypsy moths in each trap is counted.

Q. Why are pheromone traps used?

Scientists and pest managers use pheromones traps to detect new populations of gypsy moth or to track the spread of infestations. Traps may be set in various patterns at densities ranging from 1 trap per 18 square miles, to 16 traps per square mile. The design of the pattern and the density of trapping will depend on the goals of the project and the kind of information is needed.

In rare situations, massive numbers of pheromone traps may be used by scientists to “trap-out” and control new gypsy moth populations that are located several miles away from other infestations. However, once an area has become infested, collecting male moths in pheromone traps will not reduce populations or the amount of defoliation. Homeowners can sometimes use traps to see when gypsy moths are active in their area, but they should not expect the traps to control gypsy moth populations or prevent defoliation.

Q. Are pheromone traps harmful?

The pheromone is not toxic to humans, other mammals, birds, fish or insects. The traps will only attract adult male gypsy moths. There is small strip of paper in milk carton traps that is coated with an insecticide, similar to a little No-Pest Strip. This strip is used to kill the moths that fly into the trap and should not be handled or disturbed. Triangular pheromone traps do not have insecticide strips but are instead coated with a sticky material to trap the moths.

Q. Will pheromone traps attract gypsy moths and cause a new infestation to start?

No, because only male gypsy moths are attracted to the pheromone traps. Female gypsy moths cannot fly and are not interested in the pheromone. Infestations can only occur when female gypsy moths are present and lay eggs.

Q. What should I do if I find a pheromone trap on my property?

Please don’t disturb the trap. The pheromone trap will be removed in late summer or fall. The number of moths caught in each trap will help scientists located or track gypsy moth populations. The quality of the trapping data is reduced whenever a trap is lost or damaged.

Q. Where can I get some more information?

More information on gypsy moth biology and management is available from your county MSU Extension office.

Tags: fisheries & wildlife, invasive species, natural resources

Related Topic Areas

Fisheries & Wildlife, Invasive Species, Natural Resources


Deborah McCullough

Michigan State University Michigan State University Close Menu button Menu and Search button Open Close