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snowy tree cricket

Oecanthus fultoni T. Walker 1962

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map male juvenile male
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male calling male calling male mating pair
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ovipositing female ovipositing female eggs antennal markings
[warm] 14 s of calling song; male from Limestone Co., Texas; 24.8°C. (WTL585-20)
[hot] 8 s of calling song; male from Kiowa Co., Okla.; 30.3°C. (WTL585-21)
[cool] 20 s of calling song; male from Cochise Co., Ariz.: Chiricahua Mts.; 18.3°C. (WTL585-25)
[cold] 20 s of calling song; male from Socorro Co., N. Mex.; 12.5°C. (WTL585-5)
[synchrony] 20 s of calling song; males from Santa Cruz and Pima Counties, Ariz.; 24.5°C. (WTL585-30c and 585-32e)
 Click on sound bar to hear graphed song.
Sound spectrogram of 2 s of calling at 24.8°C (from WTL585-20). Dominant frequency 2.9 kHz.
Click on spectrogram to expand image of last chirp.
Song at 25°C: Regular, melodious chirps at ca. 2.8 ch/sec. in the east and ca 3.1 ch/sec. in the west. Chirps usually have either 8 or 5 pulses, produced at ca. 52/sec. A chirp's pulses are not quite evenly spaced—chirps generally begin with a group of two pulses closely followed by consecutive groups of three. Thus most chirps have pulses grouped as 2,3,3 or 2,3. Carrier frequency is 2.7 kHz.
Song data: See Fulton 1925 and Walker 1962.
Identification: Length 15-18 mm. Black mark on first antennal segment round or oval; length of black mark on second antennal segment greater than half length of segment; width of dorsal field of male forewings more than 0.4 the length; more than 35 teeth in stridulatory file.
Similar species: Riley's tree cricket—dark mark on second antennal segment reduced (less than half length of segment) or absent; center of mark near distal border of segment.
Habitat: Shrubbery and vines around houses, unsprayed fruit trees, tangles of vines and trees at edges of clearings and along neglected fence rows; broadleaved trees, esp. scrubby oaks.
Season: July to October; one generation per year.
Remarks: The snowy tree cricket is sometimes called the "thermometer cricket" because its chirps are easily countable and their rate correlates well with the temperature at the cricket. In eastern United States, Fahrenheit temperature can be estimated by counting the chirps in 13 sec. and adding 40. West of the Great Plains, the snowy tree cricket chirps a bit faster (at a given temperature) and the recipe changes—e.g., count the chirps in 12.5 sec and add 38. Of course if you are really interested in using the snowy tree cricket as a thermometer, you should calibrate your local crickets against a thermometer placed near where they sing. Count their chirps per minute at a variety of temperatures, graph the results, draw a line that fits the points, and use a little algebra to arrive at a handy formula. One explanation of why snowy tree crickets sing faster in the West is that their faster chirps are more easily distinguished from the similar but slower chirps of Riley's tree crickets, which do not occur in the East. Careful studies in the West of chirp rates in and out of the zone of overlap between snowy and Riley's tree crickets should help interpret the variation.

There is yet more to know about the song of the snowy tree cricket. Nathaniel Hawthorne described it as "audible stillness" and declared, "If moonlight could be heard, it would sound just like that." On a more commercial note, producers of movies and television shows often dub the song of this species onto sound tracks to signal that the action is taking place on a quiet summer's night in a rural or suburban setting.
More information:
genus Oecanthus, subfamily Oecanthinae.
References: Allard 1930a, 1930b; Block 1966; Fulton 1915, 1925, 1926b; Shull 1907; Walker 1962, 1969. Collins 2010-date
Nomenclature: OSF (Orthoptera Species File Online).
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