By Whitney Cranshaw, Colorado State University Cooperative Extension, Entomolgy
The most common singing crickets that are encountered in homes are the black "field crickets", Gryllus spp. Two species are found in the state, almost identical in appearance but with shifted life cycles. G. veletis predominates in spring and over winters as an adult; G. pennsylvanicus is the late summer species.
Only male crickets "sing". The sound is produced by rubbing together specialized enlarged veins on the wing. ( Not by rubbing their legs as promoted by Jiminey Cricket.) The primary vein is known as the file with numerous small raised points; the scraper on the other wing runs across this. About 95% of the crickets are "right-winged" with the file on the right wing. Crickets detect the sounds through organs (typanum) located on their front legs - in a sense hearing "with their elbows".
Several different songs can be produced, most commonly the "calling song", which may be produced loudly and for long periods to attract mates. The intensity of the calling song increases as nonmated males age. Other songs that may be produced include the "courtship song", "staying together song", and a "rivalry song".
As cold-blooded animals, chirping rates can be affected by temperature. In one case, involving the snowy tree cricket (a pale green species related to katydids and found on shrubbery) temperature can be estimated using Dolbears Law. Dr. Dolbear, a professor at Tufts University developed the following formula:
T = 50 + (N-40)/4
T = Temperature (F); and
N = Chirps/minute.
Field crickets do not reproduce in homes and those that are found there are merely misplaced wanderers that will die without reproducing. Sticky "roach motel" traps or, if in an appropriate location, dusts of boric acid will hasten their demise.
Photo: Judy Sedbrook
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888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010