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Rattler Round-winged Katydid

Rattler Round-winged Katydid (Amblycorypha rotundifolia)

Occurrence

Occasional.  Populations seem to fluctuate from year to year.

Habitat

Woodland edges, shrubby areas.

Range

Most NE Ohio counties, but not in all locations and almost absent in some years. More occurrence observations are needed. The Clicker Round-winged Katydid looks very similar but has a different song. It has been reported in parts of Ohio, but I have not encountered it in NE Ohio to date.

Physical description

Small for a leaf-mimic, and considerably smaller than the much more common Oblong-winged Katydid. Males have a brown stridulatory field (base of the wings where the song is produced); females do not. Notice how round their heads are. This is a characteristic of the Amblychorypha genus.

Song

The song sequence consists of two or three shorter series of rattles followed by a longer one. Sometimes, they will simply sing a series of the longer rattles without the short, introductory statement. I'll include examples of songs at two temperatures (warm and at 62F) that also show both possible phrasing options. They are charming songs, but rather soft and easily obscured by louder insects. If there are coneheads nearby, listening for Rattler Round-winged Katydids may be futile.

 

They primarily sing at night.

Rattler Round-winged Katydid on a warm night, then at 62F - Recording by Lisa Rainsong
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Rattler Round-winged Katydid with Sword-bearing Coneheads and Common True Katydids - Recording by Lisa Rainsong
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Adult season

The third week of July until…it varies quite a bit. Some will sing through September and occasionally into October, but numbers decrease as fall progresses. While I don’t typically find them late in the season, one year I found two singing males in the Chagrin River Valley in early November.

General description and context

One can spend a great deal of time searching for a singing male and still never succeed. When you find him, however, it will be worth the trouble because these katydids are adorably cute. They aren’t generally more than about 4 feet above the ground. A row of shrubs, brambles, and vines at the edge of the woods is a good place to look and listen for them.

Rattler Round-winged female adult and nymph
Females have broad, curved ovipositors.

Similar species

The Oblong-winged Katydid is larger, but could be confused with the Rattler Round-winged if one is not aware of just how much smaller the Rattlers are. The appearance rather than the songs would be the confusion, as their songs are quite different. Rattlers rattle. Oblong-wingeds sing, “Scritch-IT? Scritch-it-IT?” I have a song comparison on the Round-winged, Oblong-winged, Angle-wing comparison page.

Field observation

These little katydids seem to be fairly common in some years and almost nonexistent in others. More observations are needed in order to have a better idea of their numbers from year to year.

 

Listening in Nature

http://listeninginnature.blogspot.com/2013/08/rattlers-in-b.html

 

Songs of Insect:

http://songsofinsects.com/katydids/rattler-round-winged-katydid

 

Singing Insects of North America

http://www.entnemdept.ufl.edu/walker/buzz/008a.htm