Got Bugs? Build A Bat Box

Jul 2, 2020

Many firework displays are canceled this year, but if you want to see a natural spectacle that celebrates the environment, look up in the sky at night. You may see a cloud of bats swooping through the air eating mosquitoes.

This tri-colored bat is one of the 13 species of bats that call Illinois home.
Credit Steve Taylor

A single bat can eat up to 3,000 insects a night. If you want to attract bats to your property, but don't want them in your house or garage, Joe Kath said to consider installing a bat box. It will help attract the flying mammals to your yard and they will naturally control the mosquito population.

Kath is the endangered species program manager of the division of natural heritage for the Illinois Department of Natural Resources. He said the boxes need be installed a certain way, but once they are up, he said, "You have absolutely nothing to lose."

For starters, they need to be placed 15 feet off the ground and should have a south/southeast exposure in order to get the afternoon sun. 

"They need to be installed out in the open, so we always recommend the side of the building, or on a pole," Kath explained. "If you were to simply just put a bat box out on a tree, it may be obstructed by the leaves or branches and the bats won't find it." 

And how do bats find a bat box?

With their eyesight.

A common misconception about bats is that they are blind. While they do most of their navigating through echolocation, Kath pointed out, "They are most certainly not blind." He added, "The eyesight of bats is better than the eyesight of humans."

Kath said the kits to build bat boxes are inexpensive, around $20, and you can find them in the birdhouse section of any home improvement store. "Or," he said, "you can easily build one yourself with just a few pieces of wood and some screws or nails."

He said sometimes bats are quick to the find bat box. "I have seen bat boxes put up and literally, within the same day, they become occupied," Kath said. "And the neat thing is, if they do become occupied -- typically, then every year following -- the same bat, or the progeny of that bat, will likely return to that bat box."

But if bats don't immediately occupy the bat box, be patient. "I've also seen them put up for two or three years and nothing happens," he said. "Then, all of a sudden, you may get some bats." 

Kath also said bats prey upon two of Illinois' most notorious insect pests -- the corn and soybean borers. These insect pests are known for decimating corn and soybeans.

"And what are the two number one crops here in Illinois?" he said. "Corn and soybean." 

Credit Connie Kuntz

Kath said that by eating the borers, bats save the agriculture industry anywhere from $3-6 billion a year in insect control.

Illinois is home to 13 species of bats and they are legally protected in the state. Kath said bats are protected because bat population numbers continue to decline. 

Here are some reasons bat populations are declining.

  • loss of foraging and roosting habitat
  • human encroachment
  • loss of proper insect base due to overuse of insecticides and pesticides
  • vandalism of neglected or abandoned buildings where bats roost
  • unintentional or intentional killing of the animals
  • white nose syndrome

White nose syndrome is a wildlife disease that was discovered in the United States in 2006 and it only affects bats.

Since its discovery, Kath said, "We have lost more than four-to-five million bats across North America."

There is no known cure and the mortality rate of bats that are afflicted is 90-95%.

"Bats are really in a bad spot these days," said Kath. "Anything people can do to help them is greatly appreciated from a conservation standpoint." 

Citing temperature, air quality, herbicides and pesticides, Kath said, "Bats are extremely sensitive to to even the smallest changes in our environment." He noted bats have been responding to changes in temperature for several decades now.

"We're starting to see the link with the migration of a lot of different bat species to cooler climates," he said, "because areas where they roosted for hundreds and hundres of years are now getting warmer."  He explained that bats are migrating northward so they can survive. 

"They should be appreciated," he said, "because they are the proverbial canary in the coal mine And that's something everyone should respect."