20 s of calling song; male from Cochise Co., Ariz.: Chiricahua Mts.; 24.6°C. Dominant frequency 2.3kHz. (WTL588-11)
Sound spectrogram showing 4 chirps from the 20 s sample above. Click on sound bar to hear song. Click on spectrogram to expand image of last chirp.
16 s of calling song; male from Bernalillo Co., N.M.: near University of New Mexico campus, Albuquerque; 19°C. Calling from pumpkin vine and leaves several feet above the ground. Recorded by J. Banas on 21 October 2020, 21:35h.
Sound spectrogram showing 3 chirps from the 16 s sample above, starting at 2 s. Click on sound bar to hear graphed song.
Song at 25°C:
Regular, melodius chirps at ca. 1.9 ch/sec. Chirps usually have either 11, 8, or 14 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 2,3,3,3 or 2,3,3 or 2,3,3,3,3. Carrier frequency is 2.7 kHz.
Length 15–18 mm. Black mark on first antennal segment round or oval; length of black mark on second antennal segment less 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:
Snowy tree cricket—length of dark mark on second antennal segment more than half length of segment; center of mark near center of segment.
Habitat:
Vines, shrubbery, low trees and crowns of high trees; chaparral; berry bushes and wild rose.
Season:
Late June to November in southern California; August until killing frosts farther north; one generation annually.
Remarks:
Riley's tree cricket, like the snowy, can substitute for a thermometer because its chirps are easily countable and their rate correlates well with the temperature at the cricket. A recipe for estimating Fahrenheit temperature from the song of Riley's tree cricket, derived from data collected by B. B. Fulton in Oregon, is to count the chirps in 20 sec and add 38. To learn more about the relationship between chirp rate and temperature for O. rileyi, visit the Thermometer Crickets page.
