1. Can you tell the temperature by the singing of crickets?
Steven Sutcliffe

2. History 1881 First published claim in Salem Gazette
1897 First published scientific formula Dolbear’s “The Cricket as the Thermometer”
1898 Species identified by Bessay & Bessay
-The idea that temperature can be calculated by the number of chirps a cricket makes in a minute is nothing new, and has long been accepted as fact not myth. Cricket calls are species specific and often claims are made but without specifying the particular cricket species that is relevant. An example of this is found in the Farmers Almanac, where they provide a formula but not cricket species.
-The first publication of estimating temperature is found in the Salem Gazette in Brooks wrote in the Salem Gazette that an author known by W.G.B had made claim to this phenomenon in their literature. (Frings & Frings 2000)
-The first scientific formula was published by Dolbear in 1897 which used cricket chirps per minute to estimate the temperature outside. His article “The Cricket as the Thermometer” was published in the American Naturalist. The species was not however identified.
-Dolbear’s results were confirmed by Bessey and Bessay in 1898, and the species was identified as a tree cricket Oecanthus niveus (Drosopoulos & Claridge 2006)
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htBessay & Bessay confirm tp://

3. Phylogeny Review Order Orthoptera
Two suborders: Ensifera and Caelifera
Caelifera – Grasshoppers and Locusts
Ensifera – Crickets and Katydids
-As we know, crickets belong to the order Orthoptera, which may represent the oldest extant lineage of Neoptera with numerous fossils found in the Upper Carboniferous period. They share the order with grasshoppers, locusts, and katydids.
-The Order Orthoptera is characterized by their ovipositor and their saltorial hind legs and divided into two suborders Caelifera and Ensifera.
-The Caelifera suborder is made up of approximately species. Made up of Grasshoppers and Locusts and referred to as the “short horned” suborder due to small antennae. (Jost and Shaw 2006)
-The Ensifera suborder is made up of approximately the same number of species as Caelifera and is composed of the Crickets and Katydids that are referred to as “long horned” suborder due to longer antennae. (Jost and Shaw 2006)
0:51 add picture of grasshoppers, locusts, and katydids
(Huber et al. 1989)

4. Phylogeny Review
Suborder Enisfera branched off in Carboniferous period
Family Gryllidae (crickets and mole crickets)
More than 2,600 species
-Suborder Ensifera, is proposed to have branched off during the carboniferous period containing the closely related katydids and crickets. Along with very similar mechanisms for acoustic communication, they are both nocturnal in nature.
-Family Gryllidae, is made up exclusively of crickets and mole crickets and is proposed to have branched off during the Permian period.
-There are more than 2, 600 modern species of crickets that descended from a common species that lived approximately 300 million years ago. (Huber et al. 1989)
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5. Morphological Diversity
-Within the Gryllidae family, crickets show quite a large amount of morphological variation. Here is a collection of eight different cricket species that demonstrate the variety of morphology found amongst cricket species. (Huber et al. 1989)
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Figure 1.1 Morphological diversity among crickets. E) Allonembius allardi male F) Apteronemobius darwini male G) Crtoxipha columbiana male H) Burrianus pachyceros male I) Madasumma affinis male J) Oecanthus latipennis male K) Cycloptilum bidens male L) Myrmecophilus pergandei male (Huber et al. 1989)

6. Evolution of Acoustic Communication
Orthoptera: first group for sound communication
Ensifera: first animal group to communicate acoustically over long distances
Sound system: evolved once or multiple times?
-Orthoptera are the first group to use sound communication.
-Gryllidae, haglidae and Tettigoniidae might have been the first animal groups to communicate acoustically over long distances. (Otte 1992)
-The Sound system, more or less as we see it today (fore-wing file and fore-leg ear system) was already present in the ancestral lineage which gave rise to Crickets and Katydids by the end of the Permian some 250 mya . (Otte 1992)
-This Evolutionary theory is not without contest however. An alternative hypothesis is that acoustic communication evolved separately on multiple occasions rather than descending from a common ancestor. The reason for this argument is due to a the variety of acoustic communication that exists within the Ensifera suborder. The counter argument however is that the tympanal organs and stridulation structures are too complicated to have evolved more than once.(Desutter-Grandcolas 2003)
-Here in this photo we have the proposed one common ancestor theory.
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(Otte 1992)

7. What is chirping? Stridulation Not just used by insects
Rubbing wings NOT legs
-Chirping or cricket singing is actually called stridulation which is the act of rubbing parts together to produce sound. And as Aiken mentioned in his lecture, cricket chirping is the rubbing of wings together NOT legs. Crickets rub the forewings on the closing stroke of their wing cycle. Legs are involved in the processes, but as auditory receptors not sound producers.
-Stridulation is common among the Ortheoptera order but not just insects make use of stridulation. Stridulation has been observed in species of spiders (Mallinella) (Jocque 2000) and scorpions (Opisthophthalmus latimanus) (Alexander 1958) but most oddly in birds.
-The bird commonly know as club-winged manakin as studied by Bostwick and Prum has been demonstrated to have evolved a stridulation technique with it’s wings as well. It might be due to the amount of time I have spent studying stridulation in crickets but I think this kind of cool so I would like to show two videos, one of a normal club winged manakin stridulation and another video of slowed down high speed footage. (Machaeropterus deliciosus) (bostwick and Prum 2005)
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High-Speed footage of the club winged manakins

8. Mechanics of Stridulation
Modified forewing (tegmen)
Scraper and File
Often combined with resonator
-Stridulation in male crickets is produced by modified forewings known as tegmen, The tegmen form the stridulatory mechanism. (Desutter-Grandcolas 2005)
-The modified tegmen on the cricket contain three main parts, a scraper, file and a resonator.
-The file is a vein, with teeth like a comb on the ventral surface of the forewing.
-The scraper, or the pelctrum is the located on the other forewing and rubs against the file.
-The resonator “modifies the frequency spectrum of the sound and enhances its intensity”. The resonator is “formed by the enlarged membranous areas of both tegmina (among which are the harp and mirror.” (Desutter-Grandcolas 2003)
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Venation, wings areas and stridulum in crickets, illustrated in Lerneca fuscipenni (Desutter-Grandcolas 2005)

9. Stridulation Scraper strikes the file Closing of wing cycle
Harp and Mirror
-Stridulation occurs on the closing stroke of the wing cycle, as the scraper is rubbed along the surface of the file. As it strikes the teeth of the file it vibrates out a frequency that can be heard by other crickets as well as humans.
-Friction between the file and the scraper sets up vibrations in neighbouring membranes referred to as the harp and mirror. Only the inward stroke of the wings causes sound, causing cricket songs to consist of short sound pulses (Walker 1962, Nischk & Otte 2000)
-As we have learned already in class resilin is required in the click mechanism of wings so that they can complete their wing cycles very quickly, this is why it can be hard for our ears to distinguish between pulses.
-The frequency of a cricket’s call can range between a little under 5kHz to roughly 30kHz. What does this mean for humans? Well, our hearing range is about 100Hz to a little over 10kHz. This means that the human ear can only detect a portion of a cricket’s frequency range.
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10. Types of Singing Chirping is divided into three components
Pulses, Chirps and Trills
Controlled by brain in cooperation with thoraic ganglion.
Trill
Chirping
-For identification purposes and for using the cricket’s call as a thermometer is important to break down the call into identifiable components. There are three main parts to a crickets call, pulses, chirps and trills. They refer to the duration of which a frequency is audible.
Pulses “are repeated rhythmically with a constant species-specific pulse rate..” Pulses are more or less indistinguishable to the ear. Each pulse represents the scraper and file vibrating. Pulses make up the chirps and trills that are more easily recognizable.
Trills, are “secondary time structures that consists of long trains of pulses”. This a continuous set of pulses with no break. (Nischk & Otte 2000)
Chrips are the other “secondary time structure that consist of short pulses”. This burst of pulses is broken up by silence. (Nischk & Otte 2000)
Thoraic ganglion is host of the “pattern-generating networks” but is controlled by the brain. (Hedwig 2000)
In case for some reason you have never been out in the countryside and had a chance to hear a cricket’s call here are two samples of trills, and chirps.
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11. How do they Hear? Tympante Ear
Made up of 1) Tympanum 2) Tracheal Sac 3) Tympanal organ
Located on forelegs
Hearing is achieved mainly by the tympante ear on the forelegs of a cricket.
The Tympante ear is made up of three parts the tympanum, the tracheal sac, and tympanal organ. (Yager 1999)
Tympanum is a vibrating region of thin cuticle set into motion by the pressure differences created by the frequency of calling that vibrates through the air. (Yage 199)
The Tracheal Sacs allow for the tympanum to detect the pressure difference by providing a medium matching the density outside of the tympante ear (yage 1999)
The Tympanal organ is a specialized sensila that translates the mechanical signal to a neural signal that can travel by neurons to the appropriate sensory organs. (Yager 1999)
Tympanal organs are specialized tibial organs. Tibial organs are found on all six legs but only on the forelegs are they specialized for hearing. (Drosopoulos & Claridge 2006)
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Horizontal section through the right ear of a noctuid (Yager 1999) Ty = Tympanum Ts =Tracheal sac To =Tympanal Organ

12. Why do they chirp? Crickets are aggressive and territorial
Noncontact reproductive communication
Males communicate to female for attraction
Males communicate to other males to defend territory
Crickets are known to be aggressive, violent and territorial. Combat between male crickets is not uncommon. (Alexander 1958) A cricket’s song is the principal method of noncontact communication between males and other individuals.
A cricket’s song is specific to the individual species. This allows for female crickets to identify which potential mates are genetically compatible. This is particularly important because multiple species commonly occupy the same location in space and time. Mating calls are often more accurately used to distinguish species rather than morphological characteristics.
Females crickets also use a male’s song to evaluate how fit a male is compared to other genetically compatible contenders
Only males sing but males do not just communicate with females they also communicate with other males either in defending territory or provoking confrontation. Males also sing after copulation to perform “copulation guarding”. (Desutter-Grandcolas 2003)
Songs are only produced by adults and can be used to identify which crickets are capable of reproduction.
-Females exhibit a stabilizing selection on the frequency used in male songs (Moradian and Walker 2008)
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13. Body Size and Singing Body size can be a physical constraint
Efficiency of sound radiation frequency dependent
Frequency dependent on size
-For Crickets and other insects that communicate using airborne sound over long distances there exists a relationship between body size and signal frequency.
-The efficiency of the airborne sounds vibrated by a crickets wings depends on the sound-producing structures, lower frequencies require larger sound producing structures for efficient sound radiation.
-Lower frequencies are also better for communicating long distance as sound absorption is also frequency dependent. (Cocroft and De Luca 2006)
-Because singing of crickets is related to reproductive success, size of body should have an evolutionary contribution to song frequencies. As mentioned earlier song frequency of crickets undergoes stabilizing selection. The benefits of being larger with a better song should result in increased mating opportunities however there appears to a cost to producing the signal. This means that the songs of crickets must be balanced between costs and benefits (Bailey 2006)
-Evolutionary impact of body size is species dependent, For example some bush crickets (actually katydids but closely related) the male body size and mass is linked to spermataphore size but for other species it is not. (Bailey 2006)
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14. Temperature and Song
Songs not learned and only altered by temperature.
Pulse rates uniform
Warm weather increases pulse rate
Ectotherms
Finally, I will address the real question, how does temperature affect a cricket’s song?
First it is important to note that songs are not learned so variation that occurs in song is species specific. Temperature is the only factor that can contribute a noticeable difference on a crickets song.
Pulse rates are uniform and are affected by temperature linearly which makes pulse rates useful for predicting temperature changes. As temperature increases so does pulse rate. This is explained by the fact that crickets are ectotherms.
This graph is taken from an article published in the American Naturalist for the Tree Cricket. In response to Dolbear’s article, the author Robert Edes provides more evidence supporting Dolbear’s formula and identifies the species of cricket used.
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The American Naturalist

15. The Chemistry of it All
Biological processes dependent on chemical reactions
Thermoconofers vs Thermoregulators
Crickets are thermoconofers (mystery solved!)
-As, Biologists, we know that all biological process are dependent on chemical reactions. Though, we often try to forget all the scary chemistry we learned in first year, but it is important to understand how temperature affects a crickets song.
-A basic chemical fact of life is that as temperature increases so do chemical reactions, and at a subcellular level chemical reactions are responsible for acoustic calling of crickets. (Drosopoulos & Claridge 2006) That is the basic chemical explanation for the phenomenon.
-For Biologists, it is important to note that acoustic insects have two options in dealing with change in temperature in their surroundings.
-They are either thermoconofers or thermoregulators. (Drosopoulos & Claridge 2006)
-Thermoconofers are insects that let their body temperature fluctuate with the fluctuation of external temperatures.
-Thermoregulators are insects that can maintain body temperature when their outside temperature fluctuates.
-It is of no surprise that most crickets are thermoconofers and when temperatures outside increase, so does their body temperature, which results in chemical reactions occuring faster.
-Mystery solved, this is why crickets chirping can be used to estimate the temperature.
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16. Conclusion Crickets’ pulse rates do change linearly with temperature
Singing by crickets is done using their wings not their legs
Cricket singing is species specific
In conclusion, I admit that I got the idea for this project while at a BBQ and at the time did not have all the answers, so I did not even come close to impressing my friends. I would like to leave you with a couple key points so that you can (attempt) to impress your friends by showing them the old temperature cricket trick.
-First remember that temperature affects the chirps per minute. So, if a cricket trills the whole time you can’t really measure the temperature.
-Second, do not make the claim that crickets make the sound with their legs. This is a common misconception and you will quickly lose your audience if someone has to correct you on this.
-Third, and most importantly, cricket songs are species specific. So If you’ve gone and memorized a formula, make sure you know which cricket it is. Otherwise your kind of pathetic attempt to impress people will go right in the toilet.
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17. T= Temperature in Fahrenheit N= Number of chirps per minute
Dolbear’s Formula
Dolbear’s formula
For species Oecanthus niveus (The Narrow Winged Tree Cricket)
A sample of the song
I will leave you with Dolbear’s formula for which the species has been identified as Oecanthus niveus (the narrow winged tree cricket).
Here is a sample of the song. I tried to get it work but failed miserably.
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T = 50 + (N-40)/4
T= Temperature in Fahrenheit
N= Number of chirps per minute

18. Sources
Alexander, Anne J On the Stridulation of Scorpions. Behaviour 12, no. 4 (January 1):  
Bailey, Winston Insect Songs - The Evolution of Signal Complexity. In Insect Sounds and Communication: Physiology, Behaviour, Ecology and Evolution, ed. Sakis Drosopoulos. CRC press.  
Bostwick, Kimberly S., and Richard O. Prum Courting Bird Sings with Stridulating Wing Feathers. Science 309, no New Series (July 29): 736.  
Cocroft, Reginald, and Paul De Luca Size-Frequency Relationships in Insect Vibratory Signals. In Insect Sounds and Communication: Physiology, Behaviour, Ecology and Evolution, ed. Sakis Drosopoulos and Michael F. Claridge. CRC press.  
Desutter-Grandcolas, L Functional forewing morphology and stridulation in crickets (Orthoptera, Grylloidea). Journal of Zoology 236, no. 2 (6): doi: /j tb04491.x.  
Desutter-Grandcolas, Laure Phylogeny and the evolution of acoustic communication in extant Ensifera (Insecta, Orthoptera). Zoologica Scripta 32, no. 6 (11): doi: /j x.  
Drosopoulos, Sakis, and Michael F. Claridge Insect sounds and communication: physiology, behaviour, ecology, and evolution. Taylor & Francis, January.  
Edes, Robert T Relation of the Chirping of the Tree Cricket (Oecanthus niveus) to Temperature. The American Naturalist 33, no. 396 (December 1):  
Frings, Hubert, and Mable Frings Effects of temperature on the ordinary song of the common meadow grasshopper,Orchelimum vulgare (Orthoptera: Tettigoniidae). Journal of Experimental Zoology 151, no. 1 (10): doi: /jez  
Hedwig, Berthold Control of Cricket Stridulation by a Command Neuron: Efficacy Depends on the Behavioral State. Journal of Neurophysiology 83, no. 2 (February 1):  
Huber, Franz, Thomas Edwin Moore, and Werner Loher Cricket behavior and neurobiology. Cornell University Press.  
Jocqué, Rudy SIX STRIDULATING ORGANS ON ONE SPIDER (ARANEAE, ZODARIIDAE): IS THIS THE LIMIT? Journal of Arachnology 33, no. 2 (8): doi: /  
Jost, M.C., and K.L. Shaw Phylogeny of Ensifera (Hexapoda: Orthoptera) using three ribosomal loci, with implications for the evolution of acoustic communication. Molecular Phylogenetics and Evolution 38, no. 2 (February): doi:16/j.ympev  
Moradian, Nima R., and Sean E. Walker Relationships between Body Size and Sound-Producing Structures in Crickets: Do Large Males Have Large Harps? Invertebrate Biology 127, no. 4 (January 1):  
Nischk, Frank, and Daniel Otte Bioacoustics, Ecology and Systematics of Ecuadorian Rainforest Crickets (Orthoptera: Gryllidae: Phalangopsinae), with a Description of Four New Genera and Ten New Species. Journal of Orthoptera Research, no. 9 (November 1): doi: /  
Otte, Daniel Evolution of Cricket Songs. Journal of Orthoptera Research, no. 1 (December 1): doi: /  
Rost, R., and H. W. Honegger The Timing of Premating and Mating Behavior in a Field Population of the Cricket Gryllus campestris L. Behavioral Ecology and Sociobiology 21, no. 5 (January 1):  
Walker, Thomas J Factors Responsible for Intraspecific Variation in the Calling Songs of Crickets. Evolution 16, no. 4 (December 1): doi: /  
Yager, David D Structure, development, and evolution of insect auditory systems. Microscopy Research and Technique 47, no. 6 (12): doi: /(SICI) ( )47:6<380::AID-JEMT3>3.0.CO;2-P.