Using Bats For Insect Control

Using Bats For Insect Control

Wouldn’t it be great if you could significantly reduce the codling moth population on your farm without even lifting a finger? New research suggests it could be feasible simply by introducing bats into your integrated pest management (IPM) program.


Thanks to a three-year grant, Steve Tennes of Country Mills Farms, in collaboration with Stretch Island Fruit Company, is studying the integration of bats into the pest management program at his Charlotte, MI-based orchard. Seven farms total throughout southern Michigan are participating. Each farm received four bat houses provided by the Organization for Bat Conservation (OBC).

Researchers from Michigan State University are leading the entomology portion of the study, monitoring codling moth flight and damage in relationship to bat activity, and a graduate student from Eastern Michigan University is monitoring the bat activity through a passive listening device.

According to Tennes, the bat monitoring equipment listens for specific bat echo locations (the sound bats use to communicate and navigate). “From that, this equipment can tell exactly which species of bat is flying, when they’re flying, and the amount of relative bat activity at the different farms,” he says. “We’re going to correlate that to the amount of codling moth activity and damage.”

The next step, which they’re working on now, involves something called bat misting. Essentially, this means temporarily catching the bats and collecting and analyzing their guano (excrement). The bat species are identified, and the guano is evaluated for percentage of codling moth and oriental fruit moth DNA. This provides details on the number of codling moths eaten by each different bat species.

The Bat Signal

So, what can growers do to attract bats? There’s not a lot, Tennes says, other than installing bat houses. “The biggest thing is not to do certain things, and that is disturb where they’re living,” he notes. “Keep human activity to a minimum.”

There is a science to creating the bat houses, too. If you make the opening a quarter of an inch too big, for example, owls rather than bats might inhabit it — a quarter of an inch too small and the bats might not fit, Tennes says.

He notes that bats are migratory, too, which means in order for them to come back, it’s paramount you provide and maintain suitable housing. “It takes patience,” says Tennes. “Bats have one litter a year, so their reproductive rate is much slower than that of codling moth, so it takes time to build up bat populations.”

A Piece Of The Puzzle

While bats can be an excellent addition to an IPM program, Tennes is quick to note they’re not a stand-alone solution. But, with more and more synthetic insect controls being phased out, and with adult codling moths developing resistance, bats are just one more control mechanism to add to the arsenal. “This would be one tool that would go into an IPM or an organic system,” he says. “What we’re trying to do is quantify how much of an effect they can have and also give growers tools to make good decisions on how to help increase bat activity.”

Tennes adds that a crucial part of any IPM program is targeting the different stages of pests. The bats have the potential to work hand-in-hand with mating disruption, for example, to cover multiple stages of the pest’s lifecycle.

This is the first year of the study, so conclusive results likely won’t be available until 2011, but an interim report will be available by this winter, Tennes says.

Overall, he’s optimistic about the study’s outcome. “The science is there,” he says. “I think long term, this has got real promise. It’s just going to take a lot of time and patience.”