If you arrive in Seoul during the middle of summer, the first cicada chorus can be genuinely shocking. You may hear a harsh buzzing sound pouring out of trees beside apartment buildings, parks, subway entrances, sidewalks, schools, and office districts.

At first, it may not even sound like an insect. Visitors sometimes compare it to an alarm, construction equipment, electrical wiring, or a machine hidden somewhere inside the trees. The sound is produced mainly by male cicadas trying to attract females. They do not sing with their mouths. Instead, they rapidly vibrate specialized drum-like structures on their abdomens.

A hollow part of the cicada's body helps amplify the vibration, allowing such a small insect to produce an unexpectedly powerful sound. One cicada can already be loud. The full Korean summer experience happens when many males call from the same group of trees at once.

Their calls overlap until the individual insects become almost impossible to distinguish. What you hear is one continuous wall of sound. Seoul's official tourism site even describes the buzzing of cicadas as one of the sounds that announces summer in the city.

The volume can feel especially intense in Seoul because trees are often planted closely around apartment complexes, schools, parks, roads, and pedestrian areas. You are not necessarily hearing cicadas from a distant forest. They may be directly above the sidewalk, outside your window, or in the courtyard between apartment towers.

Add humid air, hard building surfaces, enclosed courtyards, and several nearby trees, and the chorus can feel as though it surrounds you from every direction. If you are preparing for a July or August visit, check my Seoul weather by month guide before packing.

When people say “the Korean cicadas,” it sounds as though one enormous species is responsible for all the noise. In reality, Korea is home to multiple kinds of cicadas, and their calls do not all sound the same.

Some create a continuous high-pitched buzz. Others produce a repeating mechanical rhythm, a pulsing call, or a rough vibrating sound that rises and falls. This is one reason summer in Korea has such a recognizable soundscape. The noise can change depending on the trees, location, time of day, temperature, and which cicadas are active nearby.

A residential street may have one dominant call while a mountain trail or riverside park sounds completely different. Even within Seoul, the experience varies. Areas with older trees, wooded hills, university campuses, palace grounds, parks, and large apartment gardens can feel much louder than streets with very little greenery.

Warm weather supports cicada activity, so their chorus often feels strongest during hot summer conditions. It is also common to notice that the sound seems to start or stop suddenly. One group may become active while another becomes quieter, creating distinct waves of noise throughout the day.

Visitors sometimes assume Korean cicadas must be unusually enormous because of how loud they are. Their size can be surprising up close, but the real secret is not simply having a large body. Their sound-producing anatomy and the number calling together create the overwhelming effect.

Cicadas are part of what makes summer in Korea feel completely different from spring or autumn. The sound becomes a seasonal signal, just like humidity, green mountains, iced drinks, and crowded Han River parks. Summer in Seoul already moves at a fast pace. Read why it feels like everyone in Korea is rushing somewhere for another side of the city's everyday atmosphere.

Cicadas are not making this noise throughout the entire year. For much of their lives, immature cicadas remain underground. They live as nymphs, feed from tree roots, grow, and molt before finally emerging.

When conditions are warm enough, mature nymphs tunnel toward the surface and climb a nearby tree, wall, fence, or other vertical structure. They then split open their old outer covering and emerge as soft, pale adults.

Their wings need time to expand, dry, and harden before they can fly away. In Korea, visitors are most likely to notice the strongest cicada presence during the hot summer period, especially around July and August.

The exact timing can shift with regional weather, temperature, rainfall, elevation, and species. Southern areas may feel different from Seoul, while mountain regions can follow another rhythm.

The first calls can seem exciting because they mark the arrival of true summer. After several weeks of hearing them outside your bedroom window every morning, the experience may begin to feel slightly less magical.

Cicada season also overlaps with some of Korea's most challenging travel conditions: strong sun, humidity, sudden rain, and long days spent walking outside. A portable charger and sunscreen are more useful than they sound when you are outside all day in Seoul.

Travelers should also plan their neighborhoods carefully so they do not spend the hottest part of every day crossing the entire city. See my guide to where to stay in Seoul before booking accommodation.

If you've ever walked through a Korean park in late July, you've probably noticed dozens of strange brown shells attached to tree trunks. At first glance, they look like dead insects. In reality, they're simply the old outer skin left behind after a cicada transforms into an adult.

The immature cicada climbs the nearest tree, fence, or wall before splitting open its shell. A brand-new adult slowly pulls itself out, expands its wings, and eventually flies away, leaving the empty shell behind.

Since thousands of cicadas emerge around the same time, these shells begin appearing everywhere across Seoul. Children often collect them, photographers use them as macro subjects, and tourists are usually fascinated because they've never seen so many in one place.

Don't worry. The shells are completely harmless. They don't bite, sting, move, or carry disease. They're simply nature's version of an empty suit of armor.

Once you've seen a few, you'll probably start spotting them on almost every tree you walk past during summer.

One of the biggest misconceptions visitors have is assuming such a loud insect must also be dangerous. Fortunately, that's not the case.

Cicadas don't hunt people, chase people, sting like wasps, or spread through homes like cockroaches. Their entire adult life revolves around finding a mate and laying eggs before they die naturally a few weeks later.

Occasionally one might accidentally fly into you. This isn't aggression. Cicadas are surprisingly clumsy fliers and simply don't have great control once they're airborne.

The loud buzzing can certainly make them feel intimidating, but they are generally harmless to people. If one lands on your shirt or backpack, it'll usually fly away again after a few seconds.

The biggest challenge during Korean summer isn't the cicadas themselves. It's the combination of humidity, heat, walking long distances, and staying hydrated while exploring Seoul.

If you're spending the day outdoors, a reusable tumbler and sunscreen are honestly much more important than insect spray.

One of the funniest cultural differences is how differently locals and tourists react. Visitors often stop, look around, and ask:

"What is making that incredibly loud noise?" Meanwhile, many Koreans simply continue walking without even looking up.

That's because the sound has become part of everyday summer life. Just as people living near the ocean eventually stop noticing waves, many Koreans have grown up hearing cicadas every single summer.

The sound becomes background noise rather than something unusual. In fact, many locals associate cicadas with childhood vacations, summer break, parks, and evenings spent outside.

To them, the sound often signals that summer has officially arrived. Visitors, however, experience it with fresh ears.

That's why so many people search online after arriving in Seoul, wondering what the loud buzzing actually is. If you're curious about another everyday habit visitors notice, read Why It Feels Like Everyone in Korea Is Rushing Somewhere.

Cicadas are closely connected to childhood summer memories in Korea. During school vacations, children often explore parks, apartment courtyards, neighborhood hills, and tree-lined walking paths with insect nets and small collection cases.

Cicadas are appealing because they are large, easy to hear, and often visible on tree trunks once you know where to look. Their empty shells are even easier to collect because they remain attached to the bark after the adult insect has flown away.

For children interested in nature, finding a cicada can feel like a small treasure hunt. The sound tells them exactly which trees to inspect, although locating the insect itself can still be surprisingly difficult.

Cicadas often blend into bark, and the noise can seem as though it is coming from everywhere at once. Insect collecting has also appeared for years in Korean children's books, educational programs, cartoons, and summer activities.

This is one reason some Koreans hear cicadas and immediately think of school holidays, hot afternoons, grandparents' neighborhoods, and childhood walks. Visitors may only hear an unbelievably loud bug. Locals may hear a familiar soundtrack connected to growing up.

You might expect Korea's loudest cicadas to be deep inside forests or mountain parks. Surprisingly, some of the most intense cicada noise can happen inside ordinary Seoul apartment complexes.

Large Korean apartment communities often include landscaped gardens, playgrounds, walking paths, courtyards, and rows of mature trees. These trees provide places for adult cicadas to rest, call, mate, and lay eggs.

Underground soil around the trees also supports the nymph stage of their life cycle. When the adults emerge, dozens may gather across a relatively small landscaped area.

The surrounding apartment towers can make the chorus feel even stronger. Hard walls reflect sound, while enclosed courtyards can make the noise seem trapped between the buildings.

If your accommodation faces a large tree, the cicadas may sound as though they are directly inside your room once they begin calling in the morning. Closing the window helps, but older buildings or thin glass may not block the sound completely.

This is especially noticeable in quieter residential neighborhoods, where there is less traffic noise to compete with the insects. The apartment landscape itself is another part of modern Korean life. Read why Korean apartments all look the same for the history behind Seoul's enormous residential complexes.

If the noise is keeping you awake, you may be wondering how long cicada season lasts. Adult cicadas do not live for years above ground.

Most of their long life is spent underground as nymphs. The visible, noisy adult stage is much shorter. Once adults emerge, their main purpose is to reproduce.

Males call, females choose mates, eggs are laid in plant tissue, and the adults eventually die. Their offspring hatch, fall toward the ground, and begin another long underground phase.

In Korea, the loudest chorus usually weakens as late summer moves toward early autumn. The exact timing depends on the weather, species, and region, so there is no single day when every cicada becomes silent.

Instead, the sound gradually changes. One species becomes less common, another call appears later in the season, and eventually the mornings begin to feel noticeably quieter.

The transition can feel surprisingly emotional. After weeks of complaining about the noise, some people notice the silence and realize summer is ending.

Cooler evenings, changing leaves, and a softer soundscape begin to replace the intense heat of July and August. Cicadas are annoying, fascinating, and deeply seasonal at the same time.

They may overwhelm visitors at first, but they are also one of the clearest signs that you have experienced a real Korean summer. For more seasonal planning, see what Seoul weather is like throughout the year.