Friday Cat-erpillar Blogging: Gypsy Moth

Top Left: Gypsy Moth Caterpillar
Bottom Left: Gypsy Moth Adult Female
Right: Oak Tree at Purdue With Burlap Band

Gypsy Moth caterpillars were found on the Purdue Campus in Spring 2013. This year (2014) the State of Indiana will aggressively target the population for eradication. The DNR is advertising its plan to the media and holding informational meetings to answer the public’s questions. The plan consists of spraying the area with a Bacillus thuringiensis strain that is effective against gypsy moth caterpillars. That will be followed by an area wide pheromone treatment to disrupt adult mating. A similar program successfully eradicated an isolated population in Indianapolis earlier this decade.

One reason for the media blitz is to answer the concerns of citizens. However, some citizens oppose any spraying on public property and spraying by government agencies. I think eradication is the right move and will lead to less pesticide use and abuse in the long run. The BT is specific for Lepidoptera and it will be sprayed on a small area where the gypsy moth population is located. The area is not a sensitive one for other Lepidoptera species. The BT has no effects on human health and non-target species, with the exception of a few Lepidoptera. The BT has no effect on bees. The BT is rapidly degraded in the environment and does not leave toxic residues.

The gypsy moth pheromone is sprayed in minute amounts that are undetectable by people. Even in much higher dose than will be used, gypsy moth pheromone has no human health effects. It is specific to gypsy moth and does not effect other Lepidoptera or other insects. It doesn’t even kill gypsy moth. It is an odor that attracts the male moths away from the females to prevent mating. The non-target effects are minimal.

If the combination of sprays works, and that is a likely outcome, the gypsy moth population will be eradicated. For the alternate scenario where gypsy moth is not treated, it will likely establish. We can look at areas where gypsy moth has established to predict what might happen. In areas with gypsy moth, outbreaks occur and trees are defoliated. Tree professionals can be overwhelmed with calls. Many homeowners panic and treat trees themselves without proper equipment. It is a situation that leads to overuse and even abuse of pesticide sprays. The eradication strategy, if successful, avoids that scenario. A few well timed sprays this year, by professionals, with minimal human health, safety and environmental impact can eliminate more haphazard and potentially harmful spraying in the future. Those who dislike pesticide sprays should consider the long run benefits of eradication sprays this year.