Chremistica umbrosa (Hemiptera: Cicadidae)

Why do cicadas sing?

Since most of us have experienced their loud shrill songs, we sometimes question: what are their songs for?
There are a few types of cicada songs: the free song (produced by undisturbed, free living males), protest song (produced when males are disturbed, injured or caught) and for some species, the courtship song (produced only in the presence of females) (Simmons & Young, 1978). The song that is normally encountered by people in the forests is the free song, or the courtship song. Male cicadas sing to attract females to mate. And because of that, the females don't sing.

Video 2: Protest calls of a captured cicada. In this video, the protest call resulted in its liberation! Video: sbtmko, Youtube.

Some cicada songs

Because cicada songs are species specific, one can usually identify cicadas to the species level just by listening to their songs. Even species within the same genus would have distinctly different songs. To faciliate comparisons between Chremistica umbrosa songs with other cicada songs, a few links are included below:

To listen to even more cicada tymbalisations, click here (for Southeast Asian cicadas), here (for North American cicadas), and here (for European cicadas)

How do cicadas sing?

In general

Sound producing system in cicadas consists of two coupled resonators: Firstly, the sound producing tymbal, and secondly, the Helmholtz resonator that consists of the abdominal air sac and tympana (Young & Bennet-Clark, 1995). The tymbals produce the sounds, the resonator radiates and amplifies the sounds produced. This is why sometimes, the singing of the cicadas is also known as tymbalisation.

Illustration 1. Permission for use granted by The Robinson Library. 1. Ventral view of cicada. 2. Lateral cross section of cicada. 3. Antero-ventral section of of tymbal area. Note that there is one pair of tymbals. For more information, refer to The Robinson Library here.

In detail The pair of tymbals of cicadas, located dorsolaterally on each side of the first abdominal segment, are responsible for the sounds they produce. Tymbals are cuticular membranes that are strengthened by sclerotised, dorsoventrally oriented ribs (Claridge, 1985). A tymbal muscle is attached to the inner face of the tymbal. The contraction of the tymbal muscle buckles the tymbal, causing a loud click that makes up the basic unit of cicada calls. Most cicadas have synchronous tymbal muscles, meaning that they require a separate nervous stimulation for every contraction, as opposed to asynchronous muscles that respond to previous cycles of nervous stimulations (Claridge, 1985). Because of this, the frequency tymbal muscle contraction is limited, and rarely reaching observed calling frequencies. Frequency multiplication takes place to reconcile muscle contraction oscillation to observed calling frequencies (Michelsen & Young, 1974) : for a call which peaks at 4kHz (in Cyclochila), the oscillation of the tymbal muscles happens at a rate of only about 120Hz (Young & Bennet-Clark, 1995). This frequency multiplication is carried out by the tymbal ribs for Cyclochila, having the ribs vibrate at 4000Hz when tymbal muscle contraction oscillation is 120Hz.This is one way for the cicada to carry out modulation of their songs, which is to vary the pitch, timing, or amplitude. Another muscle, the tensor muscle, anterior to the tymbal, serves to modify the elastic and acoustic properties of the tymbal, which could also help in song modulation (Claridge, 1985). Abdomen positioning is yet another means of song modulation- some cicadas deliberately raise their abdomen during song making to increase the gap between its operculum and the abdomen, allowing for louder acoustics (Claridge, 1985). This could explain why some cicadas adopt special 'song making' postures during tymbalisation.

Video 3. Cicada tymbalisation, by Magicicada sp. Video: Acejackalope, Youtube. The sound is made by the tymbal of the cicada, and is the protest song from this species. The vibrating part that can be seen Note that the mechanism of cicada calls (tymbalisations) is different from that used by most orthopterans, (stridulation), as tymbalisation does not involve the rubbing of one surface against another surface.

Why don't cicadas go deaf?

Interestingly, the tympana, which are used by the males as resonators for their song, are also used to detect sounds, both in the males and females. So, if the organ that is exposed to the loud and shrill songs, propagated through a forest, is also the organ that is supposed to receive sounds, could all male cicadas be deaf by the time they sing?
Hennig et al. in 1994 found that there were folds on the male tympana when cicadas were singing, but were not present when they were inactive. The folds conferred protection from 'deafness' caused by mechanical overstimulation of the tympana when cicadas were singing, reducing the cicada's sensitivity to noise by up to 20dB. A more recent study by Sueur et al. (2008) found that male cicadas of his study species had high sensitivity towards only selective frequencies, which was lower than their dominant calling frequency. Also known as frequency detuning, this allows male cicadas certain amount of sensitivity towards auditory signals, and at the same time prevent deafening. On the other hand, they found that the female tympanum was tuned very precisely to the species' dominant calling frequency, allowing optimal detection and recognition of the species specific song sung by the males. More studies could be conducted to determine if these findings can be generalised to all cicadas.

Song making posture and song modulation

For C.umbrosa, their songs are very distinct and unmistakable. Able to be heard from a few hundred meters away, their songs are shrill and continuous, punctuated short periods of by coarse-sounding portions in between. To create the coarse sounding portions, C.umbrosa seems to change the position of its abdomen, as shown in the below video.

Video 4. C.umbrosa song modulation through repositioning of its abdomen. Note that whenever the 'coarse' region of the song is sung, this male moves its abdomen downards, towards the tree branch. Video: Edwin Khoo.

When C.umbrosa is singing, it adopt a singing posture, forming a curved abdomen. This posture could possibly function to serve as protection against over-stimulation of its tympana and to increase the amplitude of its songs when it tymbalises.

Life stages

Being hemimatabulous, all cicadas go through three main stages in their life cycle, comprising of the egg, nymph and adult.

Life stage	How does it look like?	Description
Egg	Picture 6. Cicada-made slits on twig.	A female cicada after mating, would deposit eggs, through its ovipositor, into small slits made by itself on the bark of a tree.
Nymph	Picture 7: Doug Allison.	Cicada nymphs have body forms that look similar to the adult stage, only without wings. Upon hatching, the nymphs fall from the bark onto the ground. Using their fossorial front legs, the nymphs dig into the ground where they would feed and grow. They derive their nutrition from piercing their rostrum (their feeding mouthparts) into the xylem of roots, and taking in plant sap. As the nymph grows, ecdysis takes place multiple times.
Adult	Picture 8: Hectonichus, Wikimedia Commons.	The last nymphal instar digs out of the soil at night and makes its way onto a vertical surface, which usually are tree barks. There, it carries out its last moult. Emerging as a winged adult, it leaves its moulted exoskeleton (exuvia) behind on the bark. Adults, too, feed on plant fluids through the xylem vessels.

Diet

Presence of specialised structures known as filter chambers Uptake of xylem fluid --> Fluid transported to filter chamber via the esophagus --> Water is removed rapidly from the fluids in filter chamber --> Removed water is directly transported to ileum --> Remaining fluids get channeled to mid gut, where absorption of solutes occur. The filter chamber allows water to directly take a shorter route through the digestive system of the cicada, reducing osmotic dilution, and to be excreted rapidly. Details of the mechanism of this process can be obtained in the paper written by Cheung and Marshall, 1973.

Illustration 2. Diagram of cicada alimentary system. Diagram obtained from Gullan & Cranston, 2010. Permission for use granted by Wiley-Blackwell, UK.

Rapid discharge of excess water as urine According to the rate of uptake of xylem fluids, cicadas also have to excrete excess fluids in order to continue uptake at the given rate. On a day where high amounts of feeding take place, urine is quickly discharged as cicadas feed. Components in the urine are in about the same proportions as the xylem sap (Cheung & Marshall, 1973), but in lower quantities. By gently tapping its abdomen, manual discharge of cicada urine can be simulated. Urine is discharged from the anus as fine, discontinuous squirt . WARNING: 'Cicada rain' can occur as a result of numerous cicadas feeding simultaneously atop a tree. By having every individual discharging urine at intervals, the cumulative effect is that which is similar to rain. (It is therefore advisable not to be over-relieved when it suddenly rains under a tree on a warm day.)

Video 4. Chremistica umbrosa discharging urine atop a tree. Location: Labrador Park, Singapore. Video: Dr Leong, T.M.

Chremistica umbrosa life history

Chremistica umbrosa last moult

Picture 9. Nymph crawls out from the soil, where it had spent its' nymphal years. This is why it is coated with mud.	Picture 10. A split appears at the dorsal part of the thoracic exoskeleton, and the head of the cicada emerges after some struggling.	Picture 11. It removes the legs from the exoskeleton and starts to recline backwards. At this time, the legs are still relatively straight. The cicada vibrates its upper half and soon the deflated wings emerge.
Picture 12. Wings are still compressed, and tracheal threads can be seen.	Picture 13. The body of the cicada continues its recline downwards and backwards, until it is almost perpendicular to the exuvia. This movement helps in the extraction of the cicada from its exoskeleton.	Picture 14.
Picture 15. It flexes its body forward and upwards as the wings slowly inflate.	Picture 16.	Picture 17. It holds onto its exuvia with all 3 pairs of legs.
Picture 18. Using the grip on the exuvia as leverage, it fully extracts the most posterior part of the abdomen from the moult.	Picture 19. The wings are fully elongated and inflated. This process of wing inflation takes about 10 minutes from start to end. The cicada would eventually fold its wings over its body as a roof like structure. This is not yet the final colouration of C.umbrosa. The colourations would appear some time after the moult.	Picture 20. The exuvia remaining on the bark of the tree. Note the dorsal split at the center of the thoracic area.

Video 5. Cicada moulting. Even though the cicada in the video is not C.umbrosa, one can easily notice the similarities in moulting chronology between this species of cicada and C.umbrosa. Video: Robert Vingsnes.

Mating

This mating event of Chremistica umbrosa was witnessed and documented first hand in Labrador Park, Singapore. The male had been tymbalising discontinuously through for at least an hour, alone. At around 12.53pm, his persistence was rewarded.

12.43pm: The tymbalisation of this male fills the air.

12:53pm: A female flies and lands noisily a few centimeters behind the male.	Within a few seconds, it stops its tymbalisation.	The male turns around slowly to face the female.
		He then walks towards her, until they are directly facing each other. It maintains this position for about 10 seconds.
It then starts to climb onto the female.
Note the visible pygofer of the male.	Mating takes place.

Generalised external anatomy of cicadas

Chremistica umbrosa (Distant, 1904)

Taxonomy

Animalia

• Arthropoda
  • Insecta
    • Hemiptera
      • Cicadomorpha
        • Cicadoidea
          • Cicadallidae
            • Cryptotympanini Boulard, 1979
              • ChremisticaStål, 1870
                • Tridentigera (Bregman 1985)
                  • Chremistica umbrosa Distant 1904

Synonyms

Cicada umbrosa Distant, 1904
Rihana umbrosa Distant, 1906
Rihana pisanga Moulton, 1923
Chremistica pisanga Metcalf, 1963

Geographic distribution

Chremistica Stål, 1870

Chremistica umbrosa (Distant 1904)

Worldwide:

In Singapore:

Description / Morphology

Picture 22. Dorsal view of C.umbrosa on a leaf. Photo: Leong et al., 2011. Permission for use granted by Dr. Leong.

From Yaakop et al. (2005), unless otherwise stated. Body Body length: about 33mm- 35mm for males, about 20mm - 20.4mm for females Head is ground coloured Dorsal surface of thorax and abdomen are dark yellow to brown. A greenish tinge can sometimes be observed at that area. Medial and lateral obconical fields usually open Lateral obconical fields enclose a ground coloured spot On the ventral part of the body, the lateral sides from the eyes to the 8th abdominal segment are covered with short fine white hairs (technically known as 'pilosity'). Rostrum with black-brown tip reaching the hind coxae Central mesonotal fascia not connected with the spots in front of the cruciform elevation Genitalia Male genitalia is usually hidden in a cicada in its normal state. It can be slowly pried out from the pygofer region with an insect pin. Uncus is broad in male genitalia, with rounded rectangular fused lobes Bundles of reddish bristles present at the lateral edges of uncus Illustration 3: adapted from Yaakop et al., 2005. Permission for use granted by Dr Salmah Yaakop. Opercula The opercula covers the tympana of cicadas. (note: opercula = plural of operculum; tympana = plural of tympanum) Illustration 4: adapted from Yaakop et al., 2005. Permission for use granted by Dr Salmah Yaakop. Illustration 5: Yaakop et al., 2005. Permission for use granted by Dr Salmah Yaakop.

Diagnosis

• Male genitalia As described in the genitalia portion.
• Strongly diverging medial margins in the male opercula As illustrated in the opercula portion.
• Patterns of spots on mesonotum Patterns of the paramedial and lateral obconical fields.
• Dense white pilosity on lateral sides of ventral surface Very apparent from a lateral view.
• Calling song This is the best way to distinguish this species from other species, because of its distinct calling songs.

Distinguishing males from females

Male dorsal view. Photo: Edwin Khoo Male ventral view. Photo: Edwin Khoo

Male operculum strongly diverges from base (of operculum), females have simple operculum (Yaakop et al., 2005) Females have a M-shaped black marking on the dorsal surface abdominal segment 9, and not in males (Yaakop et al., 2005) Presence of ovipositor on the ventral side for females, absence for males Males tymbalise, females do not (Yaakop et al., 2005). Males have tympanic organs and tymbals while females have fully developed tympanic organs, but no tymbals. Male tympana is much larger than female tympana. Females have a sharp, pointed abdomen, while males have more rounded abdomen. Males have a pair of white patches at the dorsal lateral sides of tergite 3, while females do not. Females have dense short golden or coppery hairs, while males have less dense hairs

Female dorsal view. Photo: Edwin Khoo Female ventral view. Photo: Edwin Khoo

Type information

Phylogeny

Why is Chremistica umbrosa nested within these groups?

Cicada higher classification

How to spot cicadas in Singapore

1. Bring binoculars, or cameras with telephoto lenses attached.
2. Go around the late morning or afternoon, in very warm weather!
3. Listen out to get an indication of their presence. If there are no cicada songs on a warm afternoon, they are probably not around.
4. If you hear them, use their songs to get to a more precise location --> walk towards the source of the songs
5. Narrow the source down to one or two trees. If singing stops when you're under a tree, remain quiet and still. The cicadas know you're there. So wait until they start singing again.
6. Start by looking at the tree trunks for odd protrusions, or peculiar wing like structures --> these could be resting females!
7. If possible, use your hearing to triangulate to a more precise location of the cicada on top of the tree, and use the binoculars to start searching.
8. If all these fail, try to locate the cicadas through cicada rain --> stand against the wind direction and look out for the fine purges of cicada urine. Where the cicada rain comes from, there the cicadas are.

Discussion

Acknowledgements

Many thanks to the people who had made this wiki possible, both by willingly providing materials and by providing valuable advice. Special thanks to Dr Leong Tzi Ming, for the short but very productive interview, sharing his field experiences with Chremistica umbrosa. My sincere gratitude extends also to Dr Salmah Yaakop, Dr Max Moulds, Wiley-Blackwell, The Robinson Library, Paul Lenhart- these people made the experience of creating of this wiki page very enjoyable!

References

AGR, 2010. Introduction. In Cicada. Retrieved Nov 20, 2012, from http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1229028581727&lang=eng#img2.
Cheung, W.W.K. & Marshall, A.T., 1973. Water and ion regulation in cicadas in relation to xylem feeding. Journal of Insect Physiology, 19: 1801 - 1816.
Claridge, M.F., 1985. Acoustic signals in the Homoptera: Behavior, Taxonomy, and Evolution. Ann. Rev. Entomol., 30: 297 - 317.
Cooley, J., Marshall, D. & O'Brien, M., 2012. What is a periodical cicada? In Periodical cicada page. Retrieved Nov 20, 2012, from
http://insects.ummz.lsa.umich.edu/fauna/michigan_cicadas/Periodical/
Gogolar, M. & Trilar, T., 2004. Biodiversity of cicadas in Malaysia- A bioacoustic approach. Serangga, 9, 1-2: 63 - 81.
Gullan, P.J. & Cranston, P.S., 2010. The gut, digestion, and nutrition. In The insects: an outline of entomology (4th ed.). UK: Wiley- Blackwell.
Hayashi, M., 1987. A revision of the Genus Cryptotympana (Homoptera, Cicadidae) Part I. Bull. Kitakyushu Mus. Nat. Hist., 6: 119 - 212.
Hennig, R.M., Weber, T., Huber, F., Kleindeinst, H.-U., Moore, T.E. & Popov. A.V., 1994. Auditory threshold change in singing cicadas. The Journal of Experimental Biology, 187: 45 - 55.
Leong, T.M., Aminurashid & Lee, B.P.Y-H, 2011a. Records of the cicada, Chremistica umbrosa (Distant, 1904) in Singapore, with accounts of its mass emergence (Homoptera: Cicadidae: Cicadinae). Nature in Singapore, 4: 163 - 175.
Leong, T.M., Shunari, M., Aminurashid & Harvey-Samuel, T.D., 2011b. The jade-green cicada, Dudubia vaginata (Fabricus, 1787) in Singapore, with notes on emergence, bioacoustics and mating (Homoptera: Cicadidae: Cicadinae). Nature in Singapore, 4: 193 - 202.
Leong, T.M., Shunari, M., Leong, L.Y.K. & Foo, S.K., 2011c. Records of the black and golden cicada, Huechys Fusca Distant, 1892 in Singapore, with natural history observations (Homoptera: Cicadidae: Cicadettinae). Nature in Singapore, 4: 203 - 211.
Michelsen, A. & Nocke, H., 1974. Biophysical aspect of sound production in insects. Adv. Insect Physiol., 10: 247 - 296.
Moore, T.E., 1993. Acoustic signals and speciation in cicadas (Insecta: Homoptera: Cicadidae). In Evolution Patterns and Processes, Linnean Society Symposium No. 14, D.R. Lees & D. Edwards (eds.). London: Academic Press.
Moulds, M.S., 2005. An appraisal of the higher classification of cicadas (Hemiptera: Cicadoidea) with special reference to the Australian fauna. Records of the Australian Museum, 57: 375 - 446.
Mozgai, D., 2012. Cicadas and prime numbers. In Cicada Mania. Retrieved Nov 20, 2012, from http://www.cicadamania.com/cicadas/cicadas-and-prime-numbers/
Salmah, Y., Duffels, J.P. & Zaidi, M.I., 2005. Taxonomic notes of the Malaysian species of Chremistica Stal (Homoptera: Cicadidae). Journal of Asia-Pacific Entomology, 8, 1: 15 - 2.
Simmons, P. & Young, D., 1978. The tymbal mechanism and song patterns of the bladder cicada, Cystosoma saundersii. The Journal of Experimental Biology, 76, 27 - 45.
Sueur, J., Windmill, J.F.C. & Robert, D., 2008. Sexual dimorphism in auditory mechanics: tympanal vibrations of Cicada omi. Journal of Experimental Biology, 211: 2379 - 2387.
Yaakop, S., Duffels, J.P. & Visser, H., 2005. The cicada Genus Chremistica Stal (Hemiptera: Cicadidae) in Sundaland. Tijdschrift vooe Entomologie, 148: 247 - 306.
Young, D. & Bennet-Clark, H.C., 1995. The role of the tymbal in cicada sound production. The Journal of Experimental Biology, 198: 1000 - 1019.

This page was authored by Edwin Khoo

Last curated in 2012