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Thursday, August 25, 2005

Cicada versus Tree Frogs

Someone in Kansas asked me if the noise that they hear just before rain fall is Cicads, Locusts, or Tree Frogs.

Just to clarify, the species of Locusts native to North America, the Rocky Mountain Locust, is thought to have become extinct by 1902, so we know that the noise was not made by Locusts. During the 1880s Laura Ingalls Wilder recounts her experiences in the book "On the Banks of Plum Creek":

...Across the dooryard the grasshoppers were walking shoulder to shoulder and end to end, so crowded that the ground seemed to be moving ...

...Grasshoppers were walking over Carrie. They came pouring in the east window, side-by-side, end-to-end, across the window sill and down the wall and over the floor.

...That whole daylong the grasshoppers walked west. All the next day they went on walking west. And on the third day they walked without stopping.

...They walked steadily over the house. They walked over the stable. They walked over Spot until Pa shut her in the stable. They walked into Plum Creek and drowned, and those behind kept on walking in and drowning until the dead grasshoppers choked the creek and filled the water and live grasshoppers walked across them.

...The fourth day came and the grasshoppers went on walking. The sun shone hotter than ever, with a terribly bright light. It was nearly noon when Pa came from the stable shouting: “Caroline! Caroline! Look out doors! The grasshoppers are flying.”

The male Tree Frog has a single tone call often called the "Rain Call" which it uses when other male Tree Frogs are in close, and thus perceived threatening, proximity. The male tree frog is very terratorial and will generally use a two toned call to ward off potential mating competition and switches to the single toned "Rain Call" when other males get closer or when stimulated by loud noise such as thunder. Various species of Tree Frog are native to Kansas and so it is quite likely that the noise which you hear before rain is indeed that of the Tree Frog's "Rain Call" as a Cicadas' mating calls are not generally stimulated by either rain or external noise sources such as thunder. However, Periodical Cicadas do require rain to soften the ground to allow them to emerge initially and so their calls could indeed be assiciated with rain albeit every 13 or 17 years.

Here is a site with Tree Frog "Rain Call" audio clips:

Here is a site with Cicada audio clips:

Do you hear a chirping noise before rain and if so do you think it's a Cicada or do you think it's a Tree Frog?

I hope that that helps to answer your question about the noises before rain, as an extra bit of trivia, the smell just before rain is called petrichor, if you have any comments please let me know and if you have any other questions which you'd like me to answer for free please send them to Ben Dash at


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