Crickets and Katydids Sing Louder in the Suburbs

Researchers map the insects by where they sing.

Green leaf-shaped katydid on a branch

 Rejean Bedard / Getty Images

Crickets and katydids sing at night to attract mates. You might hear their songs from a backyard deck, but would expect the cacophony to be much louder out in the wilderness.

Researchers were amazed to discover that's not the case.

The songs are used to help map the insects' populations; the louder the song, the more insects there are. Researchers found there was more singing — and hence, more insects — in suburban areas than in urban and rural areas.

Penn State researchers said they were the first to show that "aural point count surveys," where they listened to a species' songs, could be effective in studying the population of these insect species.

Grasshoppers, crickets, katydids, and others in the order Orthopterans, are some of the most threatened insects, the researchers point out. Studying their songs is a safe way to study declining species.

"Having a nondestructive way to monitor and map these species is vital for understanding how to conserve and expand their populations," study co-author Christina Grozinger, a professor of entomology at Penn State College of Agricultural Sciences, said in a statement.

For the study, researchers identified 41 survey sites in Pennsylvania that included deciduous forest, agricultural fields, pastures, and various urban and suburban areas.

The study's lead researcher, D.J. McNeil, postdoctoral fellow in Penn State's Insect Biodiversity Center and the Department of Entomology, stood stationary at each location for three minutes, recording the number of calls from crickets and katydids, those in suborder Ensifera, which sing primarily after dark. The locations were sampled five times from July to November in 2019, all between sunset and midnight.

"You can identify birds by their calls really easily, and I came to realize that this was true for crickets and katydids," McNeil said.

"For example, one cricket species makes a particular type of chirp, and another one has a different pattern. So, over the course of a few years, I've taught myself the different breeding calls of the crickets and katydids, and I've reached the point where I can confidently identify a large portion of the species that we have in this region."

The study, published in the Journal of Insect Conservation, found that some species preferred agricultural areas, others preferred urban habitats, and others were found in all locations. But the most katydid and cricket singing was recorded in suburban areas.

"We found that intermediate levels of urbanization, such as what you'd find in suburban areas, hosted the highest number of species, perhaps because areas with intermediate levels of disturbance host the greatest number of habitat niches and can support more species than heavily disturbed or totally undisturbed ecosystems," McNeil said.

Knowing what habitat the insects prefer can help people make those habitats more welcoming, the researchers said

"We hope that this study inspires people to listen carefully to the diverse insect songs in their backyards at night and think about ways to improve the habitat for these important species," Grozinger said.