John M. Petti
Department of Entomology & Nematology
University of Florida, Gainesville, FL 32611-0620
April 15, 1997
- Download and print Chapter 24: Loudest[16kb pdf]
The African cicada, Brevisana brevis (Homoptera: Cicadidae) produces a calling song with a mean sound pressure level of 106.7 decibels at a distance of 50cm. Two species of North American cicadas, Tibicen walkeri Metcalf and T. resh (Haldman), produce an alarm call with a mean sound pressure level of 105.9 dB(50cm). Brevisana brevis is likely the loudest insect species on record. Cicada songs are species-specific and play a vital role in communication, reproduction, and possibly defense.
In the context of this paper, "loudest insect" is defined as the insect species capable of producing the most intense sound between 20 Hz and 20 kHz, the range audible to normal human hearing. Loudness will be quantified by the sound pressure level (SPL) in decibels (dB) produced by a single insect measured at a distance of 50cm using a reference value of 20 N/m2. The greatest published sample mean SPL for a species will determine the champion. The biological significance of the sound production is discussed.
Initial candidates were provided through personal communications, an Internet search for the "loudest insect" using Yahoo!, and posting a request for help on the Entomo-L Listserv. CD-ROM versions of CAB Abstracts (1985-present) and AGRICOLA (1970-present) were searched to obtain other candidates and SPL measurements. Secondary literature was used to interpret and equalize the SPL values obtained. SPL values were standardized according to Peterson (1967).
The Entomo-L Bulletin Board was the most productive source of potential candidates providing numerous species from the orders Orthoptera and Homoptera. Suggested orthopteran species include a large field cricket from Malaysia (Brachytrupes achatinus), the bladder grasshopper (Bullacris membracoides), an acridid (Circotettix rabula), and the European mole cricket (Gryllotalpa vinae) registering 96 dB at a distance of 50cm (Bennet-Clark 1970), the highest recorded SPL for these contestants. Homopteran contenders include male cicadas of the family Cicadidae. The range of mean sound pressure levels for samples of calls from the 68 species considered is 69.1-106.7 dB (Sanborn & Phillips 1995; Villet 1987; Young 1990). A maximum SPL of 108.9 dB was measured in an alarm call produced by Tibicen walkeri Metcalf (Sanborn & Phillips 1995). Mean and maximum SPL levels for finalists are presented in Table 1.
Sound pressure levels for loudest insect species finalists.
|Species||Song||Mean SPL*||Max. SPL||Reference|
|Brevisana brevis||call||106.7(10)||107.5||Villet 1987|
|Pyena semiclara||call||106.2(11)||108.0||Villet 1987|
|Diceroprocta apache (Davis)||call||106.2(8)||107.9||Sanborn & Phillips 1995|
|Tibicen walkeri Metcalf||alarm||105.9(8)||108.9||Sanborn & Phillips 1995|
|Tibicen resh (Haldman)||alarm||105.9(9)||107.2||Sanborn & Phillips 1995|
|Cyclochila australasiae**||call||105.7(8)||107.8||Young 1990|
Most male cicadas produce an alarm call and calling song that vary in SPL. I award the loudest insect record to the species Brevisana brevis (Homoptera: Cicadidae) for a mean calling song SPL of 106.7 dB (Villet 1987). Tibicen walkeri Metcalf and T. resh (Haldman) deserve honorable mention for sharing the highest mean alarm call SPL of 105.9 dB (Sanborn and Phillips 1995).
Sound is produced by cicadas when muscles buckle the tymbals, rib-strengthened chitinous membranes located on the dorsolateral surfaces of the first abdominal segment (Sanborn & Phillips 1995). The sound pulse is modified by several body components and radiated through the tympana (Young 1990; Young & Bennet-Clark 1995).
Sanborn and Phillips (1995) found that sound pressure levels for both calling songs and alarm calls of 59 species of North American cicadas correlate directly with insect body mass (R2 = 0.325 and 0.451, respectively). The dry weight of Brevisana brevis is approximately 0.3 g. Tacua speciosa and Pomponia imperatoria, southeast Asian cicadas, have dry weights of about 1.5 and 2.0 g, respectively. Anecdotal accounts of the songs of P. imperatoria suggest they are deafening. It is likely that B. brevis holds the record only because of a lack of investigation in southeast Asia (M.H. Villet, personal communication).
Most male cicadas attract mates with their calling song (Sanborn & Phillips 1995) giving larger males a competitive advantage in sexual selection. The calling song also stimulates aggregation of conspecific males (Simmons et al. 1971); and when males are in close proximity, it may repel, resulting in a minimum distance between individuals (Doolan 1981).
Smith and Langley (1978) examined the immediate and short-term effects of the male desert cicada Diceroprocta apache (Davis) alarm song on prey handling ability of an aggressive generalist predator, the southern grasshopper mouse Onychomys torridus (Coues). While the irritating call was not sufficient to deter attacks, increased handling time reduced predatory efficiency and enhanced the probability of the insect's escape.
The noise produced by cicadas could be interpreted as an advertisement for predators. At close range, the painfully intense sounds can also have a repellant effect on bird predators. Simmons et al. (1971) theorize the coexistence of different frequencies of songs produced during the simultaneous emergence of acoustically isolated sympatric cicadas may jam the hearing of predators better than one species by itself.
I thank Drs. T.J. Walker (University of Florida, Department of Entomology and Nematology), M.H. Villet (Rhodes University, Department of Zoology and Entomology, Grahamstown, RSA), H.C. Bennet-Clark, G. Tschuch, K. Reide, M. Gogala, D.R. Raichel, J. Coelho, D.D. Yager, R. Mankin, Mr. L.R. Davis Jr., C.R. Bomar, and T. Forrest for their kind assistance.
- Bennet-Clark, H.C. 1970. The mechanism and efficiency of sound production in mole crickets. J. Exp. Biol. 52: 619-652.
- Doolan, J.M. 1981. Male spacing and the influence of female courtship behavior in the bladder cicada, Cystosoma saundersii Westwood. Behav. Ecol. Sociobiol. 9: 269-276.
- Peterson, A.P.G. & E.E. Gross, Jr. 1967. Handbook of noise measurement, 6th ed. General Radio Co., West Concord, Mass.
- Sanborn, A.F. & P.K. Phillips. 1995. Scaling of sound pressure level and body size in cicadas (Homoptera: Cicadidae; Tibicinidae). Ann. Entomol. Soc. Am. 88: 479-484.
- Simmons, J.A., E.G. Wever, & J.M. Pylka. 1971. Periodical cicada: Sound production and hearing. Science 171: 212-213.
- Smith, R.L. & W.M. Langley. 1978. Cicada stress sound: An assay of its effectiveness as a predator defence mechanism. Southwestern Naturalist 23: 187-196.
- Villet, M. 1987. Sound pressure levels of some African cicadas (Homoptera: Cicadoidea). J. Entomol. Soc. South Afr. 50: 269-273.
- Young, D. 1990. Do cicadas radiate sound through their ear-drums? J. Exp. Biol. 151: 41-56.
- Young, D. & H.C. Bennet-Clark. 1995. The role of the tymbal in cicada sound production. J. Exp. Biol. 198: 1001-1009.