Species of the Month, August 2021: Singing Insects
by Mary Gartshore
With a flashlight, camera and patience you can enjoy the spectacle of singing insects in Norfolk County’s natural areas.
As the chorus of frogs and birds begins to wind down, singing insects begin to command the night airwaves. Singing insects include katydids, crickets and cicadas. This article will focus on katydids. Most have grown to adulthood in one season and are ready to find mates. One of the loudest singing insects is the Northern True Katydid, a species whose Canadian range is confined to the Carolinian Zone but in the US it extends as far as Texas. Its “rant-rant” or “rant-rant-rant” is locally known in Norfolk as “back-ache bug” or “tree-frog”. It hides chameleon-like in tree foliage and its large wings have been retooled for sound amplification, not flight. The distinct “squeeze-it” call is Oblong-winged Katydid often found sitting in full view on top of shrubs or tall flowers. The coneheads are found in grassy fields and roadside verges. The Sword-bearing Conehead sounds like maracas in August. The large, rare Robust or Crepitating Conehead (not the one that raids the fridge at midnight) has a loud buzz that is one of the fastest muscle contractions (224 pulses/sec) of any living animal and is of interest to nano-technologists. In late September the Round-coned Conehead takes the stage with its quiet buzz in native grasslands in Norfolk County.
The background chorus on a warm August night consists of six small tree crickets: Pine, Snowy, Temperature, Black-horned, Four-spotted and Two-spotted. Two-spotted is pale russet not green like other tree crickets. It arrived in Ontario en masse in 2013 and is one of the commonest katydids attracted to lights. Its song is a low “drrrrrrrr”. You can measure the night temperature using the song of Temperature Crickets. Groups of males synchronize their bell-like chirps. Count the chirps in 15 seconds and add 40 to get a reading in Fahrenheit. Male tree crickets sing to attract females and offer a liquid treat from two nipples under their wings. Females climb on top of the male to test the quality of his offering before deciding to mate.
Elliott, L. and W. Hershberger. 2007. The Songs of Insects. Houghton Mifflin Co. Boston. 228 pp, and CD.