Reading the Seasons by Cicada Song: Japan's 32 Species, Earlier First Songs and the Northward March of the Kumazemi

Cicada Song as a Calendar Made of Sound: The Basics of Japan's 32 Species

Cicadas are insects of the family Cicadidae in the order Hemiptera, and roughly 3,000 species are known worldwide. Most are found in the tropics, and according to Ministry of the Environment survey materials, 32 species live in the Japanese archipelago. Only a dozen or so occur on the main islands from Hokkaido to Kyushu; the rest are endemic to the Ryukyu Islands, such as Amami, Okinawa and Yaeyama, or are confined to tiny ranges like the Ogasawara cicada of the Bonin Islands.

Only Males Sing: The Instrument of Tymbal Muscles and Opercula

Only males sing, and the song is a courtship call to attract females. A "tymbal muscle" at the base of the abdomen contracts at high speed, buckling a thin membrane called the tymbal to produce sound. The inside of the abdomen is mostly a hollow "resonance chamber," which generates a volume out of all proportion to the insect's size. By opening and closing the "opercula" that cover the outside of the abdomen, the cicada changes the tone and loudness and beats out a rhythm unique to its species. The reason we can tell "min-min-min" from "oshi-tsuku-tsuku" is that both the structure of this instrument and the pattern of playing are genetically fixed for each species.

Six Leading Voices: A Quick Guide to Calls, Seasons and Hours

In the summer round of the Ministry of the Environment's citizen survey "Ikimono Mikke," 4,099 cicada exuviae were collected from across the country. About half were aburazemi, followed by niiniizemi, higurashi, tsukutsukuboshi, kumazemi and minminzemi. These top six species made up 96% of the total, showing that the cicadas of Japan's familiar woodlands can be described almost entirely with these six. Their calls and typical seasons and hours are summarized below.

The point of this table is that even within a single summer, "when, at what hour, and which voice you hear" differs by species. Niiniizemi begin singing at the end of June, aburazemi and kumazemi join in July, and after the mid-August Obon holiday the calls of tsukutsukuboshi and higurashi come to the fore. In other words, if you can pick out the combination of calls, you can tell how far the season has advanced without looking at a calendar. The institution that turned this "sense of season by sound" into a scientific record is the JMA phenological observation program described later.

From North to South: How the Cicada Line-Up Changes by Region

The Japanese archipelago stretches about 3,000 km from north to south and spans climates from subarctic to subtropical. The cast of cicadas changes accordingly, and the "sound of summer" in the mountains of Hokkaido and the grasslands of Okinawa is produced by entirely different species. The prefecture-by-prefecture data of the Ministry of the Environment exuviae survey show this regional character clearly.

Hokkaido and Tohoku: Forests of Ezozemi and Ezoharuzemi

In Hokkaido, exuviae of the aburazemi that dominates Honshu's cities are scarce. Instead, species that favor cool forests stand out: ezozemi, ezoharuzemi and koezozemi. The ezoharuzemi, as its name suggests (haru means spring), sings from spring into early summer, and around June the forests of Hokkaido fill with its distinctive chorus. The ezozemi prefers deep mountains, starts singing in July and falls silent between late August and early September. These species have also been collected in the highlands of Honshu, such as Nagano and Yamanashi, where high-altitude areas function as outposts of Hokkaido's fauna.

Honshu's Cities: Aburazemi, Minminzemi and Niiniizemi

In the lowlands from Kanto to Tohoku, the aburazemi accounts for the great majority of exuviae, followed by the minminzemi and niiniizemi. In Kanagawa Prefecture, aburazemi were found in 155 of 174 survey records, and minminzemi in as many as 91. The minminzemi is common in city parks in Kanto but scarce in the lowlands of western Japan, where it is confined to the hills. People from Kanto who move to Kansai are often surprised that "the minminzemi isn't singing," and this difference in distribution is the reason.

Western Japan: The Kumazemi Chorus Rules the Cities

From the Kinki region westward, the morning streets are blanketed by the great chorus of the kumazemi. The exuviae survey found many kumazemi records in Osaka, Hyogo and Fukuoka, and the species' presence jumps sharply from Shizuoka westward. The kumazemi is one of the largest cicadas on Japan's main islands, exceeding 6 cm in length, with a black body and transparent wings. Originally a species of warm regions such as Kyushu and Shikoku, its share of all cicadas in cities like Osaka has surged since the 1980s, and it is now the lead voice in the urban "sound of summer." The background to this change is examined in detail in the following chapters.

The Ryukyu Islands: Japan's Smallest Cicada Sings From March

The Ryukyu Islands from Okinawa Island westward host many endemic species of a different lineage from the main islands. The Iwasaki grass cicada (Mogannia minuta) is Japan's smallest cicada at 12 to 17 mm long. Rather than trees, it perches on grasses such as sugarcane, Japanese pampas grass and cogon grass, and sings from March to July, unthinkable on the main islands. On Ishigaki and Miyako islands its call is a seasonal sign of early summer that even makes the local news. Other island species include the tiny, all-green Kuroiwa cicada, only about 3 cm including the wings; the Ryukyu aburazemi, a close relative of the mainland aburazemi; and the Yaeyama kumazemi of the Yaeyama Islands, each having diverged island by island. The Kuroiwa cicada is declining as its habitat is lost to development, a symbol of how fragile island endemics can be.

• Hokkaido: ezozemi, ezoharuzemi and koezozemi dominate; aburazemi are limited to the south
• Lowlands of Kanto to Tohoku: aburazemi overwhelmingly, followed by minminzemi, niiniizemi and higurashi
• Cities from Kinki westward: kumazemi dominate; minminzemi are confined to the hills
• Ryukyu Islands: many endemics such as the Iwasaki grass cicada (from March), Kuroiwa cicada and Ryukyu aburazemi

A Cicada Distribution Map Is Also a Climate Map

Just as the Ministry of the Environment survey found ezozemi and ezoharuzemi not only in Hokkaido but also in the highlands of Nagano and Yamanashi, cicada distribution is set by altitude as well as latitude. Lower temperatures slow nymph development and lengthen the years needed to reach emergence, so slow-growing species struggle to survive in cold regions. Conversely, by checking which cicadas sing in a given place, you can identify its climate zone quite accurately. A cicada distribution map is a climate map of Japan drawn through the eyes of living things.

Cicada distribution is thus closely tied to climate zones. Put the other way round, if the climate changes, distributions change too. Like dragonflies and butterflies, cicadas are among the insects whose "northward shift" is best documented, and the kumazemi is the prime example.

What 70 Years of JMA Records Say About the "First Song"

"The cicadas seem to be starting early this year." In Japan, that feeling has been preserved as an official record for nearly 70 years, through the phenological observation program of the Japan Meteorological Agency.

Started in 1953, Animal Observations Discontinued in 2021

Since 1953, the JMA had used a unified method at weather stations nationwide to record dates such as the flowering of cherry trees, the first song of the bush warbler and the first song of the aburazemi. It is a globally valuable long-term dataset that captures the progress of the seasons as "the response of living things." However, citing reasons such as urbanization around weather stations making target organisms hard to find, the JMA announced in November 2020 that from 2021 it would discontinue all observations of 23 animal species, including the first song of the aburazemi, and scale back to nine phenomena in six plant species such as cherry and ginkgo.

The decision drew concern from researchers and citizens that "basic data for capturing the effects of climate change would be lost." The program that stepped in to fill the gap was the citizen-participation phenology monitoring program launched in fiscal 2021 by the Center for Climate Change Adaptation of the National Institute for Environmental Studies (NIES), in cooperation with the Ministry of the Environment and the JMA.

504 Citizen Observers Carry On the Record

The NIES monitoring program covers 66 items in total, 32 plant and 34 animal, centered on the items the JMA used to observe, with citizen observers recording flowering dates, first-song dates and first-sighting dates. As of January 2024, participants numbered 504 from all 47 prefectures. Observers choose a site they can visit three or four times a week, observe only the species they can reliably identify, and report by email or via the website. Crucially, the program is designed so that its data can be compared with the roughly 70 years of JMA records from 1953 to 2020.

A Warm Previous Summer Through Winter Brings an Earlier First Song

In June 2024, NIES announced the results of an analysis combining this citizen data with the JMA's historical data. For the first song of the aburazemi, the researchers pooled JMA records from 47 sites nationwide for 1971 to 2020 with 160 records from 115 locations logged by 112 citizen observers from 2021 onward, and compared 1,369 statistical models combining temperature, solar radiation, humidity, rainfall, wind speed and other variables.

The result was clear. The factor most strongly related to the first-song date was temperature, and specifically not the temperature of that early summer but the temperature from the previous midsummer through early winter: the warmer that period, the earlier the first song tended to be. Concretely, there was a strong negative correlation with temperatures 322 to 221 days before the first song, roughly August to November of the previous year. The effects of solar radiation, humidity, rainfall and wind speed were small. The findings were published in June 2024 in the journal Ecological Entomology as "Exploring the factors influencing the first singing date of a cicada."

The user survey "Are the cicadas singing?" that Weathernews has run every year since 2015 around July 10 (with roughly 6,000 to 15,000 responses depending on the year) also reports that the advance in first songs has become more pronounced since 2021. Observations by a specialist institute and app responses from the public, two very different datasets, are pointing in the same direction.

What a Shift in the First Song Means

A first song a few days earlier is not, in itself, fatal to any organism. The problem is that the creatures around cicadas do not necessarily move at the same pace. The breeding season of birds that rely on cicadas as a major food source, the growth rhythm of the trees whose roots the nymphs feed on, and the timing of the rainy season the eggs need to hatch are each set by different factors, so as warming advances a "seasonal mismatch" in timing can arise. The value of long-running phenological observation lies precisely in its ability to detect such mismatches as species-by-species records, and in that sense its continuation through citizen surveys underpins climate change research in Japan.

Why the Kumazemi Is Spreading North and Into Cities

Alongside the earlier first song, the best-known change in the world of cicadas is the northward spread of the kumazemi. Once "the cicada of western Japan," it now sings routinely from street trees in Kanto.

The Northern Limit Moves From the Miura Peninsula to Utsunomiya and Kanazawa

Thirty to forty years ago, the northern limit of the kumazemi was considered to be around the Miura Peninsula in Kanagawa Prefecture. Today it has been confirmed as far as Utsunomiya City in Tochigi Prefecture on the Pacific side (an adult captured in 2009 is the northernmost record) and Kanazawa City in Ishikawa Prefecture on the Sea of Japan side (exuviae confirmed for three consecutive years from 2005). Establishment has also been reported in Saitama and Ibaraki. At the time of the Ministry of the Environment exuviae survey, only one kumazemi record came from Tokyo and four from Kanagawa; now the species is vying for the lead role of summer across the Kanto region.

Over 90% of Urban Exuviae Are Kumazemi

Alongside the northward march, cities are becoming "kumazemi-ized" from within. In Osaka, the share of kumazemi among all cicadas has surged since the 1980s. In an exuviae survey conducted in 2015, 80% of exuviae in Expo '70 Commemorative Park, where a forest has been cultivated over roughly 50 years, were aburazemi, whereas in central Osaka City over 90% were kumazemi. Even within Osaka Prefecture, a mature forest and the built-up city have completely different cicada line-ups. In postwar Osaka, the urban heat island effect was layered on top of global warming, and temperatures rose at a rapid 0.29°C per decade. In that environment the once-dominant aburazemi declined, and the niiniizemi and tsukutsukuboshi are said to have all but vanished from the city center.

A Rapid Increase in Kanto Between 2022 and 2025

Comparing the nationwide "Is the kumazemi here?" surveys that NIES and Weathernews ran among app users in 2022 and 2025 shows the kumazemi's presence in Kanto growing rapidly in just three years. The increase in the share of respondents answering "yes" by prefecture was as follows.

In the Tohoku region, by contrast, no significant increase was seen over the same period. The kumazemi front is thought to be moving north across the Kanto Plain right now.

Warming Alone Cannot Explain It: Transported Plantings and Hard Soil

Researchers, however, are cautious about explaining the kumazemi's northward spread by "warming" alone. Shigehiko Shiyake, a former curator at the Osaka Museum of Natural History, points out that while global warming is thought to be one factor, its link to rising temperatures is not clear-cut, and there is also a theory that the advance of urbanization is at work. The kumazemi is estimated to fly only about 1.2 km under its own power, which would make it hard to travel from the Miura Peninsula to Utsunomiya in a few decades. The more likely route is thought to be the transport of eggs and nymphs along with street trees and garden plantings. Because kumazemi lay their eggs in dead twigs, eggs and nymphs travel with nursery stock and root balls and become established in warm cities.

The other key is soil hardness. A research group led by Professor Hideharu Numata of Kyoto University surveyed soil hardness and cicada species composition in parks in Osaka City and showed that cicada diversity falls in hard, trampled soil, while kumazemi nymphs are better than other species at burrowing into hard ground (Moriyama & Numata, 2015, Zoological Letters). Urban ground hardened by paving and foot traffic is harsh for aburazemi and niiniizemi but relatively favorable for kumazemi. Professor Numata summarized this research in the book "Thinking About Global Warming Through the Kumazemi" (Iwanami Junior Shinsho, 2016), arguing that warming and urbanization act in combination.

Warming and the Cicada Life Cycle: Separate Clocks for Egg, Nymph and Adult

A cicada's life consists of three stages, egg, underground nymph and above-ground adult, and each runs on a separate clock that responds to temperature and rain. To understand how warming affects cicadas, these three clocks need to be looked at separately.

Eggs Hatch on Rainy Days: High Humidity Is the Trigger

Female kumazemi lay their eggs in dead twigs in summer, and the eggs overwinter there and hatch the following early summer. According to research by Minoru Moriyama and Hideharu Numata of Kyoto University, once embryonic development is complete, hatching is induced by high humidity derived from rain. In the field, most hatching occurred on rainy days, and there was a significant positive correlation between the day's relative humidity and the number of eggs hatching. Even briefly submerging a dead twig containing eggs in water produced high hatching rates. Hatching on a rainy day lets the newly emerged first-instar nymphs burrow easily into soft, moist soil and reduces the risk of death from desiccation.

This is where warming comes in. The time at which eggs become ready to hatch is set by accumulated temperature after overwintering and normally falls in the latter half of the rainy season. In a warm winter, embryonic development proceeds faster and readiness to hatch comes earlier, but because actual hatching requires rain, the eggs end up "waiting" for the rainy season. Moriyama and colleagues reported this mechanism in Zoological Science in 2011 as a strategy by which the kumazemi ensures its fitness under climate warming by synchronizing hatching with the rainy season. They also showed, however, that a prolonged arrest of hatching lowers hatchability itself, so if the gap between a warm winter and the rainy season grows too wide, even this strategy has its limits.

Nymphs Spend 2 to 5 Years Underground Feeding on Root Sap

Hatched nymphs burrow into the soil, insert their mouthparts into tree roots and grow by sucking sap from the xylem and phloem. The time spent underground varies by species: roughly 3 to 5 years for aburazemi and minminzemi, and 1 to 2 years for tsukutsukuboshi. Worldwide, the nymphal period ranges from 2 years in the shortest-lived species to 17 years in the longest. Nymphs cannot move or search for roots unless the soil is soft and moderately moist. As we saw in the previous chapter, the reason compacted urban soil changes the cicada species composition is that this underground stage is strongly governed by the physical condition of the soil. The diversity of life in the soil underpins the diversity of cicada voices above ground.

In the final summer of its underground life, the final-instar nymph comes to the surface after dark, climbs a tree trunk or grass stem, splits open its back and emerges as an adult. Emerging at night is thought to make the insect harder for predators such as birds to find and less prone to drying out. The newly emerged adult's soft white body hardens by morning, takes on its true brown or black coloring, and flies off. If you search around the base of park trees on a summer evening, you will find numerous round holes about 2 cm across opening toward the surface. These are the nymphs' exit holes, and counting them gives a rough idea of how many cicadas grew up under that tree.

Adults Live Up to a Month, Not "One Week"

The story that "cicadas die a week after coming above ground" is widely known, but it is closer to a myth born from the fact that they die quickly in captivity. Recent mark-recapture surveys in the field have shown that adults live from ten days to about a month. In a 2019 study by a high-school student in Okayama Prefecture, survival of up to 32 days was confirmed for aburazemi, 26 days for tsukutsukuboshi and 15 days for kumazemi. Adults live on tree sap; males sing to call females, and once mating and egg-laying are done, their lives end. Short compared with the years underground, but far longer than the proverbial "fleeting week."

13 and 17 Years: Lessons From North America's Prime-Number Cicadas

No discussion of climate and the cicada life cycle is complete without North America's periodical cicadas. The central and eastern United States are home to cicadas that emerge en masse on 13-year and 17-year cycles, and because both 13 and 17 are prime numbers they are also called "prime-number cicadas." In 1997, Professor Emeritus Jin Yoshimura of Shizuoka University proposed the hypothesis that the nymphal period lengthened during an ice age that began about 1.8 million years ago, and that prime-number cycles survived because they prevent populations with different cycles from interbreeding and scrambling their periodicity. With a prime-number cycle, the chances of emerging in the same year as a population with a different cycle are minimized.

In 2024, the 17-year Brood XIII (northern Illinois) and the 13-year Brood XIX (the Great Southern Brood) emerged in the same year. Since the least common multiple of 13 and 17 is 221, these two broods appear above ground together only once every 221 years: the last time was 1803, and the next will be 2245. Cicadas numbering in the billions emerged at once across up to 18 states, and the two broods overlapped in some counties of central Illinois. The cicada's clock has weathered climate fluctuations on the scale of millions of years; how far can it keep pace with the warming we are experiencing over mere decades? Periodical cicadas are a living experiment that poses that question.

How Cicadas Link Forest, Soil and Water

Cicadas may seem like nothing more than a noisy presence, but within the ecosystem they play an important role in connecting underground and above ground, forest and waterside. Emerging all at once with several years' worth of forest nutrients stored in their bodies, cicadas are, in effect, "a lump of energy the forest releases each summer."

A Summer Feast for Birds, Hornets and Mantises

Adult cicadas are eaten by many predators: birds such as sparrows, starlings, crows and bulbuls, as well as hornets, mantises and spiders. The sight of a bird flying off with a cicada in its beak is common in summer parks. Underground nymphs are food for moles, and nymphs that surface to emerge are targeted by nocturnal animals. The soft body just after emergence is especially defenseless, and as if to compensate, large numbers of individuals emerge at the same time. By appearing in numbers too great for predators to consume, the group as a whole survives, a "predator satiation" strategy of which North America's periodical cicadas are the extreme form.

Exuviae and Carcasses Return to the Soil

The cicada carcasses and exuviae that fall to the ground at summer's end are broken down by ants, soil animals and fungi and return to the tree roots as soil nutrients. The nutrients a nymph drew from roots over several years feed predators above ground, and the remainder goes back to the soil. Like stag beetle larvae breaking down rotting wood, this cycle is part of the forest's material circulation.

From Forest to Pond: The Nutrient Pulse Carried by Periodical Cicadas

This role is most dramatic in the emergence years of North America's periodical cicadas. A study of forest ponds in southwestern Ohio (Nowlin et al., 2007, Ecology) showed that the massive fall of cicada carcasses into ponds in an emergence year greatly increased nutrients and biomass in the water and altered the dynamics and stability of the pond food web. The researchers describe this as "a high-quality pulse of allochthonous organic matter delivered from the forest to the water in early summer." Nutrients drawn up from tree roots travel through the bodies of cicadas into ponds and streams, and from there to rivers downstream and ultimately to coastal ecosystems. Cicadas are also "walking fertilizer" that links forest and water.

In other words, when cicada species decline in cities or their emergence timing shifts, the effects reach the birds that eat them and the soil organisms that feed on their carcasses. A change in cicada song is only the entrance to changes happening where we cannot hear them.

Recording the "First Song" Yourself: Cicada Watching as Citizen Science

Now that JMA observations have been scaled back, it is citizens who sustain the seasonal data on cicadas. No special equipment is needed. All it takes is to listen at the same place every year and write down the day you first hear them.

Join the NIES Phenology Monitoring Program

Anyone can take part in the NIES phenology monitoring program as a citizen observer. The process has four steps: send a registration email, choose a survey site you can visit three or four times a week, select only the items you can identify with confidence, and report first-song and first-sighting dates by email or via the website. The 66 target items include cicadas such as the aburazemi, higurashi and tsukutsukuboshi. What matters is "continuing at the same place every year"; data from a single site accumulated over many years becomes, in itself, a record of climate change.

Exuviae Surveys: How to Tell the Species Apart

Adults sit high in the trees and are hard to catch, but anyone can collect exuviae. Exuviae differ in shape by species, and the Ministry of the Environment adopted them as a survey method because "species can be confirmed, reliability is high, and the impact on nature is small." The main identification points are as follows.

• Aburazemi: medium-sized and dark brown all over; the antennal segments are hairy and the third segment is clearly longer than the second
• Minminzemi: about the same size as the aburazemi but somewhat paler; the third antennal segment is about the same length as the second
• Kumazemi: large and glossy dark brown, with thick, sturdy forelegs
• Niiniizemi: small and rounded; its most distinctive feature is a coating of mud over the whole body
• Tsukutsukuboshi and higurashi: medium-sized and rather slender; the higurashi has hairier antennae

Search tree trunks, the undersides of leaves and fences in parks and shrine grounds, and record the species and number of exuviae you find, along with the place and date. It makes a perfect summer-holiday science project for children, and if you keep it up for a few years, the progress of "kumazemi-ization" in your town will show up in the numbers. Like bird watching, the strength of cicada watching is that you can capture changes in nature within walking distance of home.

The ground rules for turning your notes into research-grade data are simple. First, listen at the same place and the same time of day every year; if the place or time changes, you cannot tell whether a difference is due to species or to environment. Second, when you are unsure of the species, do not force a decision; write "unknown." A wrong species name distorts the analysis more than no record at all. Third, record the days you heard nothing as "not singing." In JMA observations too, "first song" means the first call after a period of silence, and it is the record of silent days that pins down the first-song date.

Smartphone App Responses Are Real Data Too

App responses on the scale of several thousand to 10,000 people, such as Weathernews' "Are the cicadas singing?" and "Is the kumazemi here?", are also used, through joint analysis with NIES, as research data for tracking changes in distribution. A single response from one person is small, but responses pooled from across the country provide a breadth and density of information that no expert could obtain by walking the whole nation.

Enjoying Cicada Song: The "Cicada Rain" and the Daily Chorus Timetable

After all this talk of warming and urbanization, it is worth remembering that cicada song is, first of all, something to enjoy. Japanese has the word "semi-shigure," or "cicada rain," for the way the voices of many cicadas overlap like a downpour. In haiku, "cicada" is a season word for summer, and the verse Matsuo Basho composed in 1689 at Risshaku-ji temple in Yamagata, "Such stillness: the cicada's cry seeps into the rocks," is one of the best-known poems in the country. Which cicada Basho heard became a famous dispute: the poet Mokichi Saito argued for the aburazemi, the German-literature scholar Toyotaka Komiya countered with the niiniizemi, and after field investigation the niiniizemi was judged the likelier candidate given the date. Knowing the seasonality of cicada calls lets you deduce even the "sound" of a poem written more than 300 years ago.

Voices That Take Turns Through the Day

Cicada voices also take turns within a single day. Let us follow a summer day, based on the Weathernews guide.

Because the kumazemi sings mainly in the morning while the aburazemi sings from early afternoon into evening, in towns where both occur you can tell them apart as "washi-washi in the morning, jiri-jiri in the afternoon." Fewer species sing in the scorching midday, and the chorus picks up again as the evening cools. Even without a clock, the cicadas tell you whether it is morning, noon or evening.

Another way to enjoy the song is to record it. If you use your smartphone's voice recorder to keep one minute of morning and evening sound from the same spot every year, then when you compare them a few years later you will hear whether the share of "washi-washi" has grown or the "jiri-jiri" has faded. It is a rough record, but there are few creatures other than the cicada that let a family memory and a record of climate change fit in the same file.

From the Spring Haruzemi to the Autumn Tsukutsukuboshi

The cicada season is not limited to summer. The earliest singer on Honshu is the haruzemi (spring cicada), which choruses "gekyo-gekyo" in Japanese red pine and black pine forests from late April to June. Its habitat is shrinking, however, as pine forests are lost to pine wilt disease, and the places where it can be heard are becoming limited. In the mountains of Hokkaido and Tohoku the ezoharuzemi sings in June; niiniizemi follow at the end of June; aburazemi, kumazemi, minminzemi and higurashi in July; and tsukutsukuboshi join from mid-August and keep singing until mid-October. Counting the Ryukyu Islands, from the Iwasaki grass cicada in March to the tsukutsukuboshi in October, cicadas are singing somewhere in Japan for eight months of the year.