APRIL

Songs

APR 30 – Black-horned tree cricket (Oecanthus

black-horned tree cricket (Oecanthus nigricornis) (orthsoc.org)

https://orthsoc.org/sina/589a.htm

Black-horned and Forbes’ cannot be ID’d by appearance, but their songs are different in rate and frequency. Here they are, side by side, indoors. The last 8 seconds is where you can best tell the difference between the two species.

Above is Black-horned – 44 pulses per second at 3.75 kHz.

Below is Forbes’ – 51 pulses per second at 4.1 kHz.

Technically, the rates should be a bit different. At 75.9F and Forbes’ should be a tad higher (58-61)…could their being next to each other causing him to try to adjust his song just as two of the same species would do to achieve synchrony? I don’t know. s576lw63.pdf (orthsoc.org)

Tomorrow: World Species

APR 29 – Forbes’ tree cricket (Oecanthus forbesi)

Forbes’s tree cricket (Oecanthus forbesi) (orthsoc.org)

https://orthsoc.org/sina/594a.htm

Forbes’ tree cricket has a trilling song.

Here is a male with the air temperature 64 F.

Here is a male with the air temperature 83 F.

APR 28 – Pine & Tamarack tree cricket (Oecanthus pini and laricis)

pine tree cricket (Oecanthus pini) (orthsoc.org)

https://orthsoc.org/sina/587a.htm

tamarack tree cricket (Oecanthus laricis) (orthsoc.org)

https://orthsoc.org/sina/591a.htm

I have been dreading this one 😉

Pine and Tamarack tree cricket have a trilling song. Let me just go ahead and post a nice photo and video of Oecanthus pini to distract you 😉

I have many Pine tree cricket recordings at different temperatures, and a few each of Tamarack tree cricket and a mystery species in Colorado.

The issue is that I believe two out of the three males that I have possessed in the past were actually dark Pine tree crickets that happened to be found on Tamarack trees in southern Michigan.

Here is a waveform from two recordings from that I labeled O. pini at 75.2 F (42 pulses per second at 3.4 kHz) and O. laricis at 76.0 F (46 pulses per second at 3.6 kHz).

The problem is, O. laricis‘ rate should be slower at that temperature.

Listen to O. pini on SINA here: pine tree cricket (Oecanthus pini) (orthsoc.org)

Listen to O. laricis on SINA here: tamarack tree cricket (Oecanthus laricis) (orthsoc.org)

It was no help when I tried to plot the pulses per second and frequency.

I would like to mention, however, the very dark and slow trilling tree crickets found on Ponderosa pines in Colorado. They might be a new species, but might also prove to be dark O. pini with a geographically different song rate. Hopefully DNA analysis, results pending, will clear that up. Here is a waveform of their song at a similar rate to the waveform above – 76.2 F. There are 37 pulses per second at 3.3 kHz.

Here are the three species on a graph (at least the Colorado species is quite different):

In closing, I can’t offer any nice recording data on Pine vs Tamarack tree cricket. Tamarack tree cricket has never been studied in depth. Its similarity to Pine tree cricket, which can also occur on Tamarack trees, makes it even more difficult. That what makes it more difficult is that it is considered a species of special concern — so taking good numbers of them from the wild would not be good. Someone from southern Michigan would be the ideal person to get recordings in the wild.

APR 27 – Prairie tree cricket (Oecanthus argentinus)

prairie tree cricket (Oecanthus argentinus) (orthsoc.org)

https://orthsoc.org/sina/581a.htm

Tomorrow: Pine & Tamarack

APR 26 – Sage tree cricket (Oecanthus salvii)

sage tree cricket (Oecanthus salvii) (orthsoc.org)

https://orthsoc.org/sina/573a.htm

Sage tree cricket has a trilling song.

Video #1 has 27 pulses per second in a temperature setting of 62.2 F.

Video #2 has 39 pulses per second in a temperature setting of 75.7 F.

Video #3 has 53 pulses per second in a temperature setting of 85.8 F.

Here are the spectrograms for the three videos above.

This video includes two males who work at chorusing….achieving it in the end.

Tomorrow: Prairie

APR 25 – White Sands tree cricket (Oecanthus beameri)

White Sands tree cricket (Oecanthus beameri) (orthsoc.org)

https://orthsoc.org/sina/598a.htm

White Sands tree cricket has a trilling song.

This video includes a singing male White Sands, then a Four-spotted, and then a White Sands. Both species usually have longer trilling episodes…I have no idea if they were shortening the bursts of trilling on purpose.

To analyze songs, I use the free version of Raven – Raven Lite 2 (Raven Lite – Cornell Lab of Ornithology – Cornell University (ravensoundsoftware.com)

Here are different options for displaying spectrograms of frequency.

Oecanthus beameri at 68F

Oecanthus beameri at 70F

Oecanthus beameri at 75F

Oecanthus beameri at 80F

Oecanthus beameri at 80F

The spectrograms for 68F and 70F are examples of the imperfect process of determining frequency. Was the thermometer inaccurately capturing the temperature of the spot where the tree cricket was singing? Perhaps the air temperature was still in the process of dropping in one of the recordings. Could it be that these two males have a slight difference in their frequency? Maybe there is a limit to the lowest frequency at which this species sing??

Tomorrow: Sage

APR 24 – Four-spotted tree cricket (Oecanthus quadripunctatus)

four-spotted tree cricket (Oecanthus quadripunctatus) (orthsoc.org)

https://orthsoc.org/sina/582a.htm

Four-spotted has a trilling song.

This video combines a rate of 28 pulses per second, then 30pps, then 34pps and ends with 45pps – all of male Four-spotted tree crickets at different temperatures. While it is difficult to tell the difference between the first two segments, it is much easier to differentiate them from the 34pps segment and the 45pps segment. Note how the frequency also rises.

Here is a waveform of the video showing the pulse rate increasing and the rising frequency.

I want to add a bit about the interesting phenomenon involving zooming in on a singing tree cricket whose rate is about 30 pulses per second using a camera with a frame rate of 30 frames per second. It is all too complicated for me to understand…I just know it gives an interesting visual effect of the movement of the wings opening and closing.

This video was taken from a bit of a distance on a windy day – try to ignore the camera movement if you can. The wings are opening and closing at 30pps – the same speed as the frame rate of the camera. It is interesting how the movement stops as I zoom in.

Here is another video of a male singing at about 41 pulses per second. In the next video, I have slowed the video to get a better view of the opening and closing.

Tomorrow: White Sands

APR 23 – Fast-calling tree cricket (Oecanthus celerinictus)

fast-calling tree cricket (Oecanthus celerinictus) (orthsoc.org)

https://orthsoc.org/sina/583a.htm

Fast-calling has a trilling song.

The video above was taken in 2009 at Bentsen-Rio Grande Valley State Park in Texas. I was very new to tree cricketing, but suspected this was something I had not encountered before.

I never did find this male, but it plots out to Oecanthus celerinictus – Fast-calling tree cricket. It is indeed fast calling, especially when compared to the similar looking Oecanthus quadripunctatus – Four-spotted tree cricket. Both Forbes’ and Different-horned have song rates similar to Fast-calling tree cricket. The vegetation was not likely a spot from which Different-horned would be singing, and it was out of range for Forbes’.

The temperature would have been in the 80’s. (The only photo I can find of the temperature on that day was of a thermometer on the ground in the park’s garden at 2:30 p.m. while the thermometer was in dappled sunshine – 110 degrees F !) This video was recorded in the late am in full shade.

Here is Fast-calling indoors in a cooler temperature – 70 F.

APR 22 – Snowy & Riley’s tree cricket (Oecanthus fultoni and rileyi)

snowy tree cricket (Oecanthus fultoni) (orthsoc.org)

https://orthsoc.org/sina/585a.htm

Riley’s tree cricket (Oecanthus rileyi) (orthsoc.org)

https://orthsoc.org/sina/588a.htm

Both Snowy and Riley’s have chirping songs.

Even though all the tree crickets in the US sing faster as the air temperature rises, since chirping is easier for humans to count than the pulses in a rapid trill, these two species have long been considered ‘thermometer’ crickets. You can read the Snowy formula on the Singing Insects of North America website under the Remarks section here:  snowy tree cricket (Oecanthus fultoni) (orthsoc.org) and for Riley’s here: Riley’s tree cricket (Oecanthus rileyi) (orthsoc.org)

These videos and waveforms give you an idea of how slow and how fast they can chirp – depending on the air temperature.

This Snowy tree cricket male is singing on a cool autumn night when the temperature is only 52 F.

This male is singing on a hot summer night when the temperature is 84F.

Here are waveforms from these two videos:

Riley’s sounds just like Snowy, but the song rate is slower. Check the Thomas J. Walker’s graph here on pg 374: s576lwc10.pdf (orthsoc.org)

Disclaimer: The info below will likely be confusing, and possibly inaccurate, so read at your own risk ! I decided to include it in case there is a young person out there who likes a challenge, and in doing research becomes completely fascinated by sound analysis and decides to study tree crickets !

I have found what I believed to be Riley’s tree crickets in Arizona, Utah, Idaho and Colorado. When putting them within a couple of feet of Snowy from Wisconsin, the rate is not much different. However, the frequencies are slightly different. Are they adjusting their rates in an attempt to synchronize their songs?

While trying to analyze different recordings for this blog post, I ended up with a chirper from Idaho with a rate of 156. At the recorded temperature, it fell midway between Riley’s and Snowy on Walker’s graph. (Note: Walker’s graph does have two markers for males from Washington Co., Utah with a chirping rate that fell midway between O. fultoni and O. rileyi….so it is something that has been a bit of a question for some time.

The waveforms below show a rileyi group member from the western US next to a Snowy male from Wisconsin…in containers with two feet of each other. It seems like they are chorusing for a few chirps, but then you can hear the separation a few chirps later. So while the rates are not much different, there is a slight difference in their frequencies. Perhaps that can be explained with audiography science…which I am not an expert in.

Here are the slight frequency differences:

Above is 2.74 kHz and below is 2.66 kHz.

Here are two recordings at 64.8 F of side-by-side Snowy tree cricket from Wisconsin and a rileyi group male from Arizona.

Snowy male at 64.8 F

Rileyi group male from Arizona at 64.8 F

Here are ~6 second waveforms – first the WI Snowy and then the AZ rileyi group:

According to SINA, the frequency should be higher on Snowy than on Riley’s…so these two recordings would seem to match for frequencies. …but note that the one on the bottom seems a tad faster than the top – meaning this Riley’s would be singing faster than the Snowy!

I just end up with a headache trying to make sense out of the recordings I have, so it’s another one of those things I have to accept I will not be able to figure out. Perhaps someday I will try to listen to more of my recordings to assure I have a Riley’s, and then see if I attempted to put him close to a Snowy to see how the songs differed in real time. Perhaps not 😉

APR 21 – Broad-winged tree cricket (Oecanthus latipennis)

broad-winged tree cricket (Oecanthus latipennis) (orthsoc.org)

https://orthsoc.org/sina/592a.htm

Broad-winged tree cricket has a continuous trilling song.

Although I don’t have many recordings of this species, somehow I managed to get males singing in a nice range of temperatures: 51.5F, 62F, 64F, 70F and 75.2F

These screen shots from Raven Lite show how I am able to count the number of pulses per second in order to plot them on a graph.

You can ‘see’ how the speed of the song gets faster as the temperature rises.

I plotted them on graphs using Microsoft Excel – showing how both the song rate and the frequency rise as the temperature gets warmer.

APR 20 – Western tree cricket (Oecanthus californicus)

western tree cricket (Oecanthus californicus) (orthsoc.org)

https://orthsoc.org/sina/586a.htm

Western tree cricket has long runs of trilling.

This is a male of the pictipennis form of Western singing in a juniper tree in New Mexico.

Here is a one second strip of the song shown above.

Below is a pale green form of Western tree cricketing trilling at 75F.

Tomorrow: Broad-winged

APR 19 – Texas tree cricket (Oecanthus texensis)

Texas tree cricket (Oecanthus texensis) (orthsoc.org)

https://orthsoc.org/sina/577a.htm

Texas tree cricket has long runs of trilling.

Interesting aspect of Texas tree cricket song. We saw/heard that Alexander’s and Walker’s can synchronize their songs, that Walker’s can have intermittent bursts of trilling when they first start singing in the evening, that Narrow-winged and Davis’ are difficult to tell apart in the field, and that Two-spotted has pre-trilling clicks when they first start singing in the evening. Now we introduce Texas tree cricket with pre-trilling clicks. I can’t say whether this is an intermittent behavior, or also a warm-up when they first start singing in the evening.

For comparison, here is Two-spotted.

APR 18 – Davis’ tree cricket (Oecanthus exclamationis)

Davis’s tree cricket (Oecanthus exclamationis) (orthsoc.org)

https://orthsoc.org/sina/590a.htm

Davis’ tree cricket has long bursts of trilling.

I find it difficult to determine if I am hearing Davis’, Narrow-winged or Two-spotted tree crickets in the field. All three have interrupted bursts of trilling.

Both Davis’ and Narrow-winged are singing in this video.

Here is a quiz 😉 Who is singing in each of the videos below? Davis’? Narrow-winged? Two-spotted? All three were taken at 70 – 72 F.

APR 17 – Narrow-winged tree cricket (Oecanthus niveus)

narrow-winged tree cricket (Oecanthus niveus) (orthsoc.org)

https://orthsoc.org/sina/584a.htm

Narrow-winged tree cricket has an intermittent bursts of trilling song.

This was recorded with the temperature in the 60’s.

This was recorded with the temperature around 80 F.

Here are comparisons of the song pattern in the 60’s versus 80.

These show the slower rate with a temp of 64F and faster rate with a temp of ~80F.

APR 16 – Two-spotted tree cricket (Neoxabea bipunctata)

two-spotted tree cricket (Neoxabea bipunctata) (orthsoc.org)

https://orthsoc.org/sina/601a.htm

Neoxabea bipunctata usually has a fast, frantic sounding call in warm temperatures – but at times can sound a bit calmer and mournful.

This male was recorded at approximate 65 F – 77 pulses per second.

This male was recorded at approximately 77 F – 120 pulses per second.

Here are Neoxabea bipunctata and then Oecanthus niveus on the same evening within 5 feet of each other.

I personally find it challenging to tell the difference between Neoxabea bipunctata and Oecanthus niveus out in the field. Folks with a better sense of frequency differences can apparently more easily tell them apart.

APR 15 – Different-horned tree cricket (Oecanthus varicornis)

different-horned tree cricket (Oecanthus varicornis) (orthsoc.org)

https://orthsoc.org/sina/593a.htm

Different-horned has a long trilling song

The WAV and image above are from a recording with a temperature of 26.6 C (79.9F)

Here is a male singing indoors at 22.0 C

Here is a male singing at 31.5 C (88.7 F) in Resaca de La Palma State Park in Texas:

You can tell the difference in rate at these two temperatures. Below are three images showing the pulse rate differences at 22.0, 26.6 and 31.5 C.

Oecanthus varicornis and Neoxabea bipunctata are two of the fastest singers in the US. Oecanthus forbesi is also one of the fastest singers.

Tomorrow: Two-spotted

APR 14 – Walker’s tree cricket (Oecanthus walkeri)

Walker’s tree cricket (Oecanthus walkeri) (orthsoc.org)

https://orthsoc.org/sina/574a.htm

Walker’s has a long trilling song

The first time I heard one singing was in late afternoon, about an hour before dusk. I was VERY excited that I had found what I believed was Oecanthus leptogrammus. I was hearing a song pattern similar to that of Oecanthus niveus, bursts of trilling with pauses between them. At that time, there were no recordings available of O. leptogrammus.

This recording was made indoors, but it is the type of pattern I was hearing in a Tepejuage tree in Bentsen-Rio Grande Valley State Park. Rather than the long continuous trilling of other nigricornis species, this was bursts of trilling with pauses between them. This was taken at 8 p.m. in June, indoors.

Another interesting aspect of their song, note the slightly lower frequency at the initiation of each burst — that’s seen in Neoxabea.

Note: The really fascinating synchrony I thought that was present on one recording might possibly be looping! I’ll investigate further. Here, however, is the actual video.

APR 13 – Alexander’s tree cricket (Oecanthus alexanderi) 

Alexander’s tree cricket (Oecanthus alexanderi) (orthsoc.org) 

https://orthsoc.org/sina/575a.htm

Alexander’s has a long melodic chirp

Note how the single chirps below have at least 8 groupings of 3 pulses…Snowy and Riley’s have 2, 3 or 4 groupings.

The male below is moving as he sings, affecting both the amplitude and length of the chirps.

Below shows Alexander’s tree cricket chirping in proximity to a trilling species. The aborted chirp at the end occurs occasionally, and in this case seemed more consistent with the presence of the other species. More will be discussed tomorrow under Walker’s tree cricket.

APR 12 – Multiple Species Singing

Several videos with more than one species singing.

Tomorrow I will begin covering various US species, including their pulse patterns, pulse rates and song frequency.

APR 11 – Rate by Temperature or Frequency by Rate Graphs

The warmer the air temperature is at the spot where a male tree cricket is singing, the faster he will trill or chirp. You can also make species comparisons by plotting the frequency against the pulse rate. This method is especially useful when you don’t know the air temperature at the spot where the male was while singing.

Relationship between body temperature and air temperature in stridulating male crickets, Gryllus bimaculatus (Orthoptera: Gryllidae): South African Journal of Zoology: Vol 28, No 2 (tandfonline.com)

Dr. Thomas J. Walker created two graphs showing pulse rates by temperature relationships, and one graph showing chirp rates by temperature relationships. They can be found on the Singing Insects of North America (SINA) website using the following links:

s576lw62.pdf (orthsoc.org) – pg 308

s576lw63.pdf (orthsoc.org)  – pg 782

s576lwc10.pdf (orthsoc.org) – pg 374

This graph shows pulses per second by frequency for each of the ten species in the nigricornis group found in the US. Two square markers indicate a species I hope will be determined as different from Oecanthus pini. They look remarkably similar, but the song is slightly different. Hopefully DNA results later this year will prove they are a new species.

APR 10 – Warm-up Clicking

From my encounters, I have heard this only with Neoxabea.

Typically I only hear this clicking with the initial calls at dusk…that’s why I call it warm-up clicking. I do not know the purpose.

Neoxabea bipunctata

Neoxabea cerrojesusensis – apparently the champions of warm-up clicking !

Tomorrow:  Rate by Temp

APR 9 – Chorusing

When several males are singing near to each other, they often synchronize their songs. The thought is that by increasing their volume, more females from further away will be drawn to the area.

For a more scientific overview, here are some papers:

(PDF) Evolution of synchronies in insect choruses (researchgate.net)

(PDF) Precedence effects and the evolution of chorusing. (researchgate.net)

The chorusing crickets of Kudremukh – IndiaBioscience

Abstract: Modelling the effects of chorus species composition and caller density on acoustic masking interference in multispecies choruses of crickets and katydids – ScienceDirect

A rain forest dusk chorus: cacophony or sounds of silence? | SpringerLink

APR 8 – Suburban 3^rd Floor Patio

My first encounter with a tree cricket was on a small patio on the 3^rd floor of an apartment complex (Tree Cricket – Neoxabea bipunctata – BugGuide.Net) – “An accidentally grown sunflower on my small 3d story patio was the chosen singing spot for a male Neoxabea bipunctata in the fall of 2006. I was smitten with not only his singing; but also the fact that he had made 5 separate holes of the same size, shape and location on each of 5 leaves…which he used as a baffle to amplify the sound of his song by putting his opened wings over the hole. Amazing.”

You can see photos at the bottom of this page:
https://oecanthinae.com/?page_id=1858#:~:text=JANUARY%201%20%E2%80%93%20The%20First%20Encounter%C2%A0

I managed to grow quite a few plants on that 5’ x 8’ balcony: several flowering plants, goldenrod, crabapple tree, grapevines, viburnum and a small potted conifer. My neighbor called it a menagerie. I transported different tree cricket species to my patio and kept them in oversized sleeves. This video gives you an idea of how well they worked. I would release the tree crickets to an adjacent field and cemetery late in the season.

Below are WAV files (Waveform Audio File) of different species on that small 3rd floor patio singing when the temperature was between 70 and 73 degrees Fahrenheit. See if you can tell the genus or species group while listening to the top three. The last five are mostly nigricornis species group…but there is one from the varicornis species group. They all trill. You might here others in the background on some recordings. Perhaps you can try plugging these into RavenLite or another program to analyze them.

Tomorrow:  Chorusing

APR 7 – Where the Tree Crickets Sing

Tree crickets can be found on many types of vegetation.

APR 6 – Direction of Sound

The position of your ears in relation to the angle of the singing tree crickets’ wings is very important. This is an excellent article about turning while singing and ventriloquism. Those of us who search for tree crickets know this phenomenon very well!

This paper (1984) gives an excellent overview of direction of sound and ventriloquism.

Directional calls and effects of turning behaviour in crickets (journals.co.za)

Same article:  Directional calls and effects of turning behaviour in crickets | Journal of the Entomological Society of Southern Africa (journals.co.za)

These videos give examples how the sound changes depending on the position of the wings.

Oecanthus quadripunctatus

Oecanthus forbesi

Oecanthus quadripunctatus

This is why finding a singing male tree cricket can often be so challenging.  Is the low volume song you are hearing because it is farther away, behind vegetation, or you are standing above or to the side of the wings?? Pine tree crickets singing from a large thick conifer can be VERY challenging. You think you are standing right in front of it, but cannot see it. It is soooooo loud, yet not visible.  You walk to the other side of the tree….oh!  It’s actually over here….still can’t find it. It seems like any spot around the tree is where the tree cricket is….arrgghh.

Tomorrow:  Where the Tree Crickets Sing

APR 5 – Baffles

Interesting:  1. a device used to restrain the flow of a fluid, gas, or loose material or to prevent the spreading of sound or light in a particular direction

2. totally bewilder or perplex

What is interesting to me is that both can be used in searching for a singing male tree cricket  😉

Male tree crickets use a variety of methods for trying to increase the volume of their song with the use of baffles.

While they often take advantage of natural shapes or already existing openings…one species is very good at creating holes in leaves. The only species I have seen create holes is Neoxabea bipunctata. The first one I encountered was the male who created holes on sunflower leaves on my third floor patio. One or two years later another male made holes on a grape plant. Most recently, I recorded a captive male and a netted male creating holes and using the leaf as a baffle.  All these cases involved N. bipunctata.

I’ve always thought of it as tree cricket males are essentially making their wings larger with the use of leaves.

Use of a self-made sound baffle by a tree cricket | Nature

How to make the perfect baffle — an insect’s guide | by eLife | Life on Earth | Medium  (Also check out the beautiful photo)

 Tree cricket baffles are manufactured tools – Mhatre – 2018 – Ethology – Wiley Online Library

 Snowy on cup plant hole…not an intentionally created hole

This male Neoxabea bipunctata (Two-spotted) is in the beginning stage of creating a hole in this leaf to use as a baffle.

The hole is a bit larger, with the edges getting smoother.

This is another individual…note how he seems to be making measurements of the hole.

APR 4 – Frequency Spectrograms

Disclaimer:  I have very limited understanding of measuring frequency.  I learned how to get the proper kHz value by analyzing recordings from SINA which also provided the kHz measurement.

I know the definition: Frequency measures the number of vibrations or waves (sound waves) that pass by each second. This is measured in Hertz (Hz) or Kilohertz (kHz). What I have trouble with is understanding why am I measuring it on the point of the spectrogram where I know I should…and where is the peak frequency on the same spectrogram?  People have offered explanations, but it’s just one of those things I accept that my brain cannot understand. (p.s.  No emails please….I’ve moved on)  😊

So you will not be learning anything from me here! 

I used to use an AVS program to determine frequency. On this graph I would have looked for the highest point, which in this case I know is the pointed single peak at about 2.8 kHz. However, what always confused me was the similarly tall values to the far left.

The spectrograms at Raven Lite are a bit easier for me to grasp. To get the measurement used for tree cricket song frequency, I simply place the cursor in the center. The spectrograms above and below are both from singing males of Neoxabea bipunctata. One has a frequency of 2.8 kHz and the other is closer to 2.9 kHz.

The colors themes are simply choices available in the program. Here are some pretty spectrograms of a few species from different groups.  Enjoy!  😉

These ½ second strips below give a better view of the values. The frequency varies with species and pulse rate/temperature. The first two show species with a similarly slow rate, yet the frequencies are different. The same goes for the bottom two – species with fast rates yet different frequencies.

Oecanthus quadripunctatus  36 pulses per second at 3.5 kHz

Oecanthus latipennis  37 pulses per second at 2.5 kHz

Oecanthus forbesi  90 pulses per second at 4.5 kHz

Oecanthus varicornis  80 pulses per second at 3.3 kHz

When I post the songs of individual species soon, hopefully the differences between these frequencies will be evident.

This paper covers tree crickets adjustments to their song frequency:  Changing resonator geometry to boost sound power decouples size and song frequency in a small insect | PNAS

Tomorrow:  Baffles

APR 3 – Pulses & Patterns

Males of species in the US, Canada, Mexico and Central America have three basic patterns of singing:  continuous trilling, intermittent trilling and chirping.

Oecanthus males in the nigricornis group and varicornis group species have continuous trilling songs.

The niveus group species and the genus of Neoxabea have intermittent trilling songs.

The rileyi group species have continuous chirps. The chirps vary in length, especially between species, and the rates vary with air temperature.

This is continuous trilling:

Pine tree cricket  – nigricornis group

Forbes’ tree cricket – nigricornis group

Texas tree cricket – varicornis group

Different-horned tree cricket – varicornis group

This is intermittent trilling: 

Narrow-winged tree cricket

Two-spotted tree cricket

This is chirping:

Snowy tree cricket

Alexander’s tree cricket

APR 2 – Waveform Basics

Disclaimer:  I am not a sound expert. In 2010 I was taught the simple method of counting the number of pulses in one second, or the number of chirps in one minute, to determine the pulses per second rate of trilling song species or the chirps per minute rate for chirping species. That is a method I can handle. These days, however, analyzing the song has become more technical and mathematical. That I cannot handle, so I will only be offering basics here.

This web page gives some basic information:  Waveforms – Teach Me Audio

Here is more info:  Audio Waveform (motionbox.io)

For tree crickets, the cooler the air temperature is at the spot where the male is singing, the slower will be the pulse or chirp rate. Conversely, the warmer the temperature, the faster they trill or chirp.  

Walker TJ, Collins N. 2010. New World thermometer crickets: the Oecanthus rileyi species group and a new species from North America. Journal of Orthopera Research 19: 371-376 s576lwc10.pdf (orthsoc.org)

Effects of temperature on chirp rates of tree crickets (Orthoptera: Oecanthidae): South African Journal of Zoology: Vol 27, No 2 (tandfonline.com)

The images below show the pulse rate in blue (waveform on top) and the frequency in yellow and pink (spectrogram on bottom). I include them both here to show that you can just as easily count the number of pulses using this type of frequency spectrogram. In fact, there are times when there is a very poor waveform, but I can still manage to count the pulses using the spectrogram…for some reason it seems to be more consistently able to display what is happening.

The strips below represent different species at different temperatures. I won’t be identifying species or providing temperatures here…my intention is to give you a number of examples to see how rates and frequencies vary.

Each strip has individual pulses or chirps (in blue), so you can count the pulses in one second.  The chirps can be counted in 10, 20, 30 or 60 seconds. Just multiply accordingly for any timespan less than 60 seconds.

Note:  Amplitude of the blue pulses are not important. It may be affected by the distance of your device to the singing tree cricket, the angle the device is in relation to the open wings, or the surrounding vegetation which might be blocking some of the sound waves.

We will examine the waveforms and spectrograms of various species in the coming weeks, and will refer often to Dr. Thomas J. Walker’s graphs posted on the Singing Insects of North America website (SINA).

APR 1 – Mechanics of Tree Cricket singing

This month I will be offering various videos, WAV files, spectrograms, waveforms and jpegs to highlight the singing of male tree crickets. Today we will cover basic mechanics.

The stridulatory teeth and file are located near the center of the medial edges of each tegmen (aka forewing).

As I mentioned in the February 2 blog entry (wing closures) the speed of the wings opening and closing is mind boggling. Each pulse or chirp occurs with the closing of the wings.

First, however, the male needs to lift his wings.

Many times, I see the male do a bit of an ‘unhitching’ move or jerk. Exactly what they are doing mechanically to their wings, I don’t know. Perhaps they are just overwhelmed with the prospect of singing….like an adrenaline rush.

These videos provide visuals of this motion…although too fast to see each opening and closing.

This video of a singing male Forbes’ tree cricket is extremely slowed down. Note the wings are not opening very wide, they don’t need to…the stridulatory file is less than 2mm long.

Tomorrow:  Waveforms