Bugs songs of summer
While bugs are commonly observed in the High Country, some are easier heard than seen. Many insects stay out of sight, for example in trees, and since they have ways to communicate with each other through the noises they make you hear them. For many bugs, the songs they create are very effective ways to find mates. If you listen carefully, you can determine which bugs you are hearing. This article briefly describes three tree-dwelling bugs you will hear as the summer progresses.
Perhaps you've heard the phrase the "dog days of summer," which refers to those hot summer afternoons in the months of July and August. A common bug called the dog day cicada (there are several species in NC) takes its name from this saying, since these bugs sing on hot days in mid- to late summer. Cicadas are harmless tree-dwelling bugs that are three or more inches long, with clear wings and a body bordered in green. These cicadas are not to be confused with the red-eyed periodical cicadas that come every 13 or 17 years (and in huge numbers). Our dog day cicada is found every year. Male cicadas produce a very high pitched "buzz" using a part of their body that acts a lot like a drum. Their song is made to impress and attract the silent female cicadas. The females lay eggs in small branches, and once hatched the small juvenile cicadas, called nymphs, bore into the ground and feed on tree roots. Cicadas spend from two to up to even ten years underground feeding. After they emerge as adults from their soil home, they may leave impressive mud "chimneys" in your yard. Like all insects, as cicadas young grow larger they must shed their hard exoskeleton, leaving the old one behind on trees. Kids sometimes delight in finding these cast off "skins" and impressing their parents and friends with them! Although it's true cicadas feed on numerous species of trees, these bugs do not cause enough damage to be of concern.
Cicada cast skin photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org
When the sun goes down, the bug songs of summer change, as the katydids and tree crickets start putting on a show. Unlike the cicada, these insects sing by rubbing their wings together very rapidly. If you listen closely, especially to katydids, you can detect a "friction-like" noise. Although both katydids and tree crickets sing together on summer nights, these two groups of bugs can be clearly told apart based on their songs and method of singing.
There are several species of katydids in our area, and the sounds they make are in some ways similar. These impressive three-inch long bugs are tree-dwellers and leaf-color green, so you seldom see them. Indeed, their color is a natural defense against what might eat them, since katydids blend in with their environment very well. Much like the cicada, the male katydid produces his song to attract females, who respond with a mild chirp. Perhaps most impressive is the "chorus" produced as a group of katydids from one set of trees is responded to by another group nearby. Listen carefully and you can imagine the insects saying "katydid", followed by a response "katydid'nt". Depending on the number of bugs, the chorus is impressively loud and a regular feature of summer evenings in the High Country.
Photo credit: Joseph Berger, Bugwood.org
But how do katydids actually hear the songs of katydids so that they can respond to them? This happens because they have an ear drum-like structures on their front legs, which they hold out to intercept the sound.
Finally, tree crickets differ in a few ways from cicadas and katydids, in that they are smaller and beige instead of green. They are also night singers, but their song is more regular. Rather than a back-and-forth chorus, tree crickets make an almost constant high-pitched hum. Though the crickets nightly song is perhaps a bit monotonous compared to katydids, these bugs definitely let us know our trees are alive with bugs!
So when you are listening to nature on summer nights, let yourself be entertained by the mating songs of the katydids and the tree crickets. And adding to the show, as summer wanes and temperatures drop, the sounds of our nighttime singing bugs change. The cooler air after dark affects the bugs, since they respond to the temperature around them. Rather than a loud and somewhat rapid tempo, their songs slow down. These variations in songs add to the fascinating sounds produced by bugs that are seldom seen but always ready for you to listen. If you want to learn more, you can find additional information using the searchable website https://content.ces.ncsu.edu.
Snowy tree cricket photo credit: Joseph Berger, Bugwood.org
References:
J. Baker. Annual or Dog Day Cicadas- NC Extension Service. 2014
Insects that feed on trees and shrubs. 1991. Second Ed. W.T. Johnson and H. H. Lyon (eds.). Comstock Publishing Assoc., Cornell University Press. Ithaca, NY
Wisconsin Horticulture
https://hort.extension.wisc.edu/articles/katydids
Missouri Department of Conservation
https://mdc.mo.gov/discover-nature/field-guide/tree-crickets
Grasshoppers and Crickets of North Carolinahttps://www.insectidentification.org/insects-by-type-and-region.php?thisState=North%20Carolina&thisType=Grasshopper%20or%20Cricket