Orthoptera, Suborder Ensifera
- This page contains pictures and information about Crickets and
Katydids Biology that we found in the Brisbane area, Queensland, Australia.
- Crickets and katydids are in insect Order Orthoptera,
Suborder Ensifera. They are among the most commonly seen insects. Their size ranges from 5mm to 100mm.
They usually have very long hair-like antenna, usually longer than
their body length.
Most of them have the hind
legs highly developed, much stronger and larger than the front two pairs of legs.
They are good in jumping.
- The adult insects have four wings. The front
wings, knows as tegmina, are tough and narrow comparing with the hind wings.
At rest, the hind wings folded like a fans, covered and protected by the
tegmina. The flight is mainly achieved by the broadly opened membranous hind
wings and the tegmina give only little help.
- Details about insect structure can be found in this page.
- Eggs are ovoid to cylindrical in shape. They are usually laid on vegetation in groups.
- Crickets and
Katydids are incomplete metamorphosis.
Their young, the nymphs, look much
the same as their adults excepts smaller and wingless. Later instars have
wing buds but still cannot fly.
Katydids species sing by stridulation. Males use sound to attract females.
For most species sound is produced by rubbing modified portions of the forewings
together. A good example of how cricket makes those sound can be found in
- We found a female Gum-leaf Katydid feeding on a gum
tree at night in Wishart bushland during late summer 2001. We took it home for
a closer observations. After two days, she started to lay eggs. Totally she
batches of eggs before we put it back to the bush. The pictures below
showing she was laying the first batch of eggs on the edge of a gum tree leaf.
- The katydid laid ten eggs along the edge of a gum tree
leaf. The eggs were dark brown in colour, in oval disk shape with 4mm in
length. The eggs looked like plant seeds. The katydid lay totally three batches (10, 8, 9 in qty) of eggs
every alternative night.
- The following pictures show the katydid laying eggs on gum stem.
- She first cuts an opening on the stem using her sharp ovipositor.
Into which she lays the hard, black and
- She carefully glues their eggs in row, then she repeats the whole
procedure for another egg.
- We noticed one thing quite interesting. We
kept the katydid openly in a corner of our room on a branch of gum
The katydid had no problem on staying there for the whole day. But every
time after she laid her eggs, she had the very strong intention to move to
another location, even if we tried to stop it. After it flied to the other
corner of our room, we put it back to the same branch of leave, then it
stayed there comfortably until laying the next batch of eggs. We think this
could be the instinct of the katydid that naturally selected to avoid too many eggs laid at the same
- The female lay eggs on leafs and stems. Their ovipositor are short when
compare with other species of katydids. But it is strong and sharp, as shown in
the above picture. It is used for cutting the surface of the leaf or stem, into which the hard, black and
disk-like eggs are laid. Then the female carefully glue their eggs in row.
Because they lay eggs on plants and their eggs look like plants materials,
katydids are sometimes distributed by nursery stock.
- We found some katydid eggs in the wild on mid winter season.
Notice the openings on its front legs, known as tympana, which is
the sound receptors. They are the organs
our ears, are to hear. The female katydid uses them to locate the males by
their love songs.
Let's have a closer look of the katydid front leg. The drawing shows the
foreleg of the katydid, which is the typical example of insect legs except there
is the special organ tympana. The tympana is only found on katydids' and crickets' forelegs, and not on
other legs nor on any legs of other insects.
All insects have three pairs of legs. These legs can be variously modified
depending on the type of insect. Basically each leg has 6 segments. The coxa
connects the leg to the thorax. Leading outward are the segments: trochanter,
femur, tibia, and tarsus. The tarsus comprised of 3-5 very
small segments. At the end of the last tiny segment is the claw. There
are usually spines on the tibia. The tarsomere on the tarsus is
the part in contact with the ground.
For more information on insect body parts, please see the Insect
- Mole crickets make sound by stridulation. Males produce songs and build burrows to amplify
their love song to attracted females. Females also stridulate but their calls are lower
and most often they do it to protect their burrows. Some reference books
suggested that females response to males' love song also by stridulation as
- In mating season, female mole crickets look for males to mate. The males play their love songs at the entry of their
burrow. It is believed that
females, by judging the sound, can determine
the health of the male and the quality of the nest that the male
prepared. It seems that the females preferred the wet nest and usually
the males will only play their love songs in the wet evening. In a summer
evening, if there is rain during the day, we will always hear the loud mole cricket
sound everywhere in Brisbane. Sometime We can trigger the mole cricket songs by
watering the garden just before evening.
Love songs from male
crickets are a series of loud, deep tones repeated regularly about two times per
second. But it is not quite regular when start. The mole cricket may have to
fine tune his song by trying different positions to get the best sound quality.
Press the following buttons to hear the different.
Non- regular pattern, recorded at the beginning of the song, 10 sec.
Click here to hear calling song,
- Regular pattern song, 10 sec. The
mole cricket play it for 30min.
- Love songs from male
crickets are a series of loud, deep-toned chirps, like crick-crick,
crick-crick, crick-crick repeated regularly about two times per second. They only
play for a short periods of
time. They start playing when the sky turns dark and end singing when the sky
is dark completely, for about 30 minutes. They do not play songs if the
soil is dry. The shape of their burrow is
believed to help amplify their songs. It is difficult to locate them by their songs
even if you are within a meter from them. If you come a bit closer, they
will stop playing. They may resume the song after a minute or so if no
more disturbance. Those songs are so loud that you may think that they are the
Rubbing Forewings and Touching Ceiling
- Most field crickets and katydids play their love songs by rubbing their left
forewing with their right forewing. Common
Mole Cricket play their love songs in a sightly different way. The songs from
field crickets and katydids usually consist of a carrier frequency and then
modulated with pulses. This is generated by rubbing the forewings, each pulse
correspond to a stroke of rubbing forewings. The songs from Mole Cricket are characteristic
by the addition series of chirps, the further modulation on the pulses and carrier frequency.
The chirps are generated by the forewings touching the burrow ceiling. Details
of carrier frequency, pulses and chirps are explained in the following
- With the Mole Cricket's forewings under the microscope, we can see the file vein
with stridulatory teeth on left forewing and the peg vein on the right
forewing. The file vein is on the wing bottom while the peg is on wing top, and
they are facing each other. By a stroke of rubbing both forewings, this generate one pulse of
modulated carrier frequency.
- First picture shows the bottom view of the left forewing, where the file
vein with stridulatory teeth locate. The second picture shows the top view
the right forewing and the location of the peg.
- The Mole Cricket playing the love song at the entrance
of its burrow. When a stroke of opening and closing of its
forewings, this generate one pulse of carrier frequency. The frequency
depend on the number of teeth on the teeth vein and the speed of moving
- Besides the pulses, the songs from Mole Cricket are characteristic
by the addition series of chirps, the further modulation on the pulses and carrier frequency.
The chirps are generated by the forewings touching the burrow ceiling. The male mole cricket plays the love song standing at the entrance of his burrow
and facing inwards. By rubbing two
forewings together, the mole cricket generates the pulses. By touching the
forewings to the ceiling, the mole cricket generates the chirps.
- The first picture shows the left forewing of a male Mole Cricket. Notice the area which in contact
with the ceiling, it had been worn out a bit, showing that part was
rubbed with the ceiling. The second picture shows when the Mole Cricket
rubbing its forewings, with the wings in contact with the burrow ceiling,
This enhance the vibration transmitted to the hard shell, which join between
the forewings and the abdomen.
- By the inspection of the male Mole Cricket specimen, we found that 2/3 of it abdomen
under the wing's base is hollow. There is a hard shell that connects between the
base to the hollow cavity. If the Mole Cricket rubs its forewings WITHOUT
touching the ceiling, the sound generate is comparatively small. If the Mole
Cricket rubs its forewings AND touching the ceiling, which enforce the
transmission of vibrations to the abdomen. The empty space inside
the abdomen acts as the resonance
chamber for the 1st amplification of the sound. By touching the forewings to the
burrow ceiling in a constant interval, this generate the chirps.
- Three Stages of Amplification
- The Mole Cricket Songs are so loud because there are three stages of
amplification. Field crickets and katydids rub their wings and amplify
the sound by the wings surface. The loudness is beyond compare with Mole
- As mentioned above, by transmitting the vibrations to
the empty space of the abdomen , the hollow abdomen is used as the resonance
chamber for the 1st amplification of the sound.
- Mole Crickets build their nest chambers
with volume, i.e., the
resonance frequency close to the pitch of the love song they play. The thorax of the mole cricket is just like a plug at the
entrance of its burrow. By standing inside or outside a bit, the mole cricket can fine
tune the volume of the chamber, i.e. the resonance frequency. Then the sound is further in
resonance with their burrow chamber. This is the 2nd amplification stage of the love
- Mole crickets build the entrance of their burrows in horn shaped. This
acts as the third stages of the amplification. The horn also direct the sound to
improve the efficiency.
- The mole cricket playing their
love songs by its forewings rubbing together and touching the ceiling of the
burrow. The second picture shows the three stages of amplification - the hollow abdomen, the resonance
chamber and the horn shape entrance.
- We have studied a mole cricket calling site and opened the chamber. The left picture shows the horn and the entrance. The right picture shows the internal of the
- Love songs from male
crickets are a series of loud, deep tones repeated regularly. The sound consists
of carrier frequency, pluses and chirps. It is worth to go back and listen again.
- Analyse the Sound Waveforms
- The Mole Cricket Song repeated regularly in a pattern. To know exactly how
Mole Cricket play the song we need an expensive high speed camera, and a bit of
Mole Cricket may not be willing to play under the heavy equipment set up. However,
by carefully analyse the sound waveforms patterns and what we have observed
above, we can reasonably describe how
the Mole Cricket play the song.
- We recorded the sound by a hand-held tape recorder 200mm - 300mm above the Mole
Cricket. Then we play back to the PC sound card via a condenser microphone
and recorded by the 'Sound Recorder' program within Windows98. We analysed the
sound waveforms using a free software 'Cool Edit' downloaded from http://www.syntrillium.com.
- The sound is a series of chirps, with about 5 chirps per second. Within each
chirp, there is seven pulses. Within each pulse, there is the 2.1KHz carrier frequency.
- Waveform 1. In the waveform picture, 'A' is one chirp. The picture
shows two second, i.e., ten chirps of the sound. The second picture shows
the frequency spectrum of the sound, indicates the base frequency is 2.1KHz.
- Waveform 2. The chirp 'A', with seven pulse 'B'. The pulse rate is
about 90 pulses per second.
- Waveform 3. One of the seven pulse 'B', and the 2.1KHz base
- Waveform 4. The picture shows the waveform at the end of a chirp.
Notice that the last pulse with the amplitude about 1/4 of the normal
pulses. This is sometime happen at the last pulse of the chirp. I think this
is due to the Mole Cricket low down its wings too early, i.e., rubbing its
wings without touching the ceiling. This made the amplitude significantly
- Now we can summarize what we found and describe how the Mole Cricket
generate its love song. The Mole Cricket rubs its forewings in a constant
speed. Each stroke generates a pulse of carrier frequency 2.1KHz. The
Mole Cricket rubs its wings at the rate of 90
cycles per second. This generates the pulses within the chirp. The Mole
Cricket move its whole body slightly up and down five times a second, so it
forewings in contact with the ceiling five times a second and generate the
chirps pattern. The whole process
make the crick-crick, crick-crick sound.
Questions for Discussion
Why it is the male katydid who made the calling, and not the female?
- Evolution theory would predict that if there were any risks involved then
the sex offering the higher investment should take fewer risks. Since eggs
are more expensive than sperms, the facts that the risk of detection by
predators of calling individuals, males are more likely to call than
- 1. Insects
of Australia, CSIRO, Division of Entomology, Melbourne University
Press, 2nd Edition 1991, pp 369.
- 2. Insects of Australia and New Zealand - R. J. Tillyard, Angus
& Robertson, Ltd, Sydney, 1926, p94.
- 3. Northern
Territory Insects, A Comprehensive Guide CD - Graham Brown, 2009.
- 4. A Guide to the Katydids of Australia - David Rentz, CSIRO PUBLISHING, June 2010.
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