Summer’s Symphony: Insect Songs Send Messages, Reveal Environment Secrets

 

In August, cicadas sound like grinding scissors in the trees in the heat of the sun. Their songs fade at dusk when crickets become more vocal and the katydids start singing their names from perches on bushes and trees. These are among the most easily recognized insect songs in the Chicago region during the waning days of summer.

        “They bring back memories and they remind us summer isn’t going to last forever,” says Carl Strang, a retired Forest Preserve District of DuPage County naturalist. Strang has been documenting the presence of singing insects in 22 counties in the Chicago region, southeastern Wisconsin and parts of Michigan since 2006.

        His research is showing how singing insects—cicadas, grasshoppers, crickets and katydids—can reveal messages about habitat and climate change. Forest Preserve District of Cook County naturalist Negin Almassi is working with Strang and Kathleen Soler to start a citizen insect monitoring project. A pilot project began in July at the Cook County forest preserve Sagawau Field Science Station, in Lemont, where Almassi works.

        The project is teaching volunteers to recognize the 12 most commonly heard insects in the Chicago region and how to document them in the field. “We’ll be looking at biodiversity and the changes in ranges,” says Almassi, who hopes to expand the project next year.

        Insects are among the most numerous of species in the world, and can be difficult to find and identify, says Strang. But monitoring those that sing is fairly easy, he says, adding “I consider singing insects a good representative of other groups of insects.”

        Documenting insects is important because some studies suggest insect numbers are declining worldwide, Almassi explains. “Singing insects, along with other insects, are a really important part of the food web,” she adds.

        Studies show that nearly one-fourth of the diet Eastern Bluebirds feed their young are crickets and grasshoppers, and that the color pigments in these insects are important to the young birds’ development. Woodpeckers and songbirds eat cicadas, and Almassi has watched a robin try to steal a cicada from another in the summer.

        “Years ago, on a long summer drive, you’d have to stop to wash and scrub the bugs that landed on your windshield,” Almassi says. Today, that phenomenon is less frequent, notes Almassi.

        All cicadas sing, most crickets and katydids sing and some grasshoppers sing. The songs come from the males that are courting females. Cicadas and grasshoppers mostly sing during the day. Crickets often sing day and night; and katydids mostly sing at night. After mating, females lay eggs that often spend the winter beneath the soil. “The young hatch when it gets warm, and it takes them a while to make it to adult form and get to their singing perches,” says Strang. In some species, like the spring field cricket, the eggs hatch and overwinter as nymphs, so they can get a head start with their singing in May or June.

        Cicadas produce songs by vibrating a membrane on the side of their bodies. Crickets and katydids rub their wings together to sing. Grasshoppers produce their songs by rattling their wings while flying or rubbing their hind legs against a folded wing.

        The most common daytime insects heard singing in summer neighborhoods July through September, and sometimes even into October, are one of four species collectively called the dog-day cicadas.

        “They’re closely related and look quite a bit alike—that’s common among the singing insects,” Strang says. “They distinguish themselves by sound, so they don’t really need to look all that different.” A species of concern is the prairie cicada, a small insect only found in some remnant prairies in the region, he says.

        Cicadas prefer sunny, warm days to sing. Grasshoppers also sing during the day. Different species emerge from early to late summer. A common summer species is the Carolina grasshopper, which hops in plain view on hot days across dirt roads and fields. When it sings, it hovers in place a few feet off the ground with the wings making a rattling sound, Strang says.

        Ground and tree crickets along with the fall field cricket—the large, black one that sometimes enters homes in late summer—sing during the day, although they are more vocal at night.

        Most of the ground crickets start singing in mid-July, including the Allard’s ground cricket, which emits a rapid musical trill. The snowy tree cricket, named because of its light color, is one of the most common singing insects in the region. It gives a series of pleasant, one-pitched, soft chirps. The speed in between each chirp has been used to determine temperature. The fall field cricket gives a loud chirp about once every second.

        In Illinois, the sphagnum cricket only lives at Volo Bog. Strang predicts global climate change will dry up the bog, and the sphagnum cricket will disappear from the state.

        Strang’s cricket song studies have led him to document the northerly expansion of the jumping bush cricket. He’s heard them in Lake, Cook, Will and DuPage counties in the past few years in spots where they’ve never been documented. They sing in late August, often in residential neighborhoods. “They’re difficult to see, but you can hear their fairly loud, brief, high-pitched, chirps,” he says.

        The summer nighttime chorus is a blend of crickets and katydids. A ticking watch sound comes from the greater angle-wing katydid, for example. The most common is the common true katydid, which sings, “Katy did. Katy didn’t,” in a harsh, raspy voice.

        Almassi has lead public singing insect programs for the past four years. “It’s magical—the things that we hear,” she says.

 

Sheryl DeVore is the author of several books and hundreds of articles on nature, the environment and health. She can be reached at [email protected].

 

Resources and Programs

To hear the 12 most common insect songs and learn about the singing insect monitoring project, visit SingingInsects.net. Carl Strang’s nature blog includes information on regional insects at NatureInquiries.wordpress.com.

Two free singing insect programs are offered at Sagawau Environmental Learning Center, 12545 W. 111th St., in Lemont. Preregistration is required at 630-257-2045.

Aug. 29 – 7 p.m. Ages 12 and older can hear an indoor presentation on singing insects followed by a naturalist-led walk listening for crickets, katydids, cicadas and grasshoppers.

Sept. 1 – 1 p.m. A naturalist will guide families outdoors to observe and listen to grasshoppers.