The use of insects, arachnids, or other arthropods to indicate a greater evil.
Bugs are creepy, we all know that. But invariably, they are used to quite different flavor than the insidious serpent, usually to more straightforward scary effect. Snakes Are Sexy on occasion, but bugs? Pretty much never. And because things with too many legs, too many eyes, and a myriad of alien body parts often involved in the uglier sides of nature repulse us so much, it only seems natural that they become the symbols of monsters.
This trope specifically describes insects (and spiders) as motif, but never the direct threat. In horror fiction, quite often the true villain's lurking evil is heralded by the appearances of unwelcome many-legged things, less often of unusual size than unusual number. Perhaps they'll come out of holes in the walls or begin populating attics or basements. Maybe you can trace the villain's nest to the greatest concentration of them. Maybe they're not even really there, and only the monster's chosen victim can see them.
There is a lot of overlap with several tropes on the Scary Animals Index:
- Spiders Are Scary: The crown champion of this trope—if you start seeing spiders, whatever is at the center of their abode is bad, bad news. Perhaps it's due to the relative subtlety of spiders that they are used so often to get under our skin: while, say, snakes and wasps can be characterized by the inextricable bite or sting, a violent and rapid intrusion, spiders are patient, not aggressive attackers or pursuers, but no less unsettling and threatening.
- Flies Equals Evil: Subtrope to this one. Flies are known for feasting on dead things, like the vultures of the arthropod world. Their association with corpses means they make a very effective scare tactic and motif for evil in one. If you're in an area flies call home, odds are something wants you dead and it isn't just the flies.
- Messy Maggots: A rarer but still effective form of this trope. Maggots, being baby flies, carry all the symbolism of flies with the added exponent of being slimy, wriggling, and generally disgusting. They're often used more literally (as in, you won't see them coinciding with Maybe Magic, Maybe Mundane often)—maggots being of a more visceral flavor, their usage in this trope tends to be restricted to the monsters that will very much rip your head off and eat it.
- Creepy Cockroach: Roaches are unequivocally associated with filth. If you've seen one, there's a million more hiding out of sight, and the damn things are near-impossible to kill on a singular basis, let alone get rid of. Because of how they hide out of sight and their attraction to unclean areas, you see these often associated with malignant evil that encroaches from the dark.
- Creepy Centipedes: These bugs are relatively obscure in this role; while essentially being stretched-out spiders in all the ways that matter (venom, hunting habits, rather subtle), they're very antisocial animals and it's difficult to conceptualize them swarming (and often all the more difficult to draw or animate). Nonetheless, their reputation is nearly black, and they have even less heroic examples than spiders, perhaps due to said relative obscurity, making them ideal critters to signal nasty beings that like to hide in dark, damp places like they do.
- Macabre Moth Motif: Moths work well with this trope due to their "back porch" aesthetic; you most often find them in the same scenes you'll find something watching you from the woods. Moths may resemble butterflies, but they move, twitch, and jitter around much more like roaches or other unwelcome bugs. The moth variant is often used with a more ancient or psychological bent due to their attraction to old, dusty things they like to chew on and human creations such as clothes and lamps.
The key to this trope is the inherent threat while lacking in overt or immediate violence. Bees and wasps are rarely used due to their tendency towards swarming a threat plus their association with stinging—and a large number of deaths in real life linked to such. Conversely, you rarely see ants because, while they swarm in much the same way as bees, you're very unlikely to get more than a couple days' burning itch from a bad encounter with one. In real life, these things are easily ignored even if they are present, and so they don't make good heralds of evil. Note that every trope listed as crossing over with this one involves a critter that is known more for the negative feelings it induces more than a direct threat posed by the animal itself.
That's not to say you can't have such bugs used for this trope, it's just harder to work with them. On the topic of notable exceptions, perhaps the most common iteration of this trope in Japan is Butterfly of Death and Rebirth due to the symbolism described on that page. While it's a far-reaching trope, you're far more likely to find it used for horror — ranging from vaguely sinister to gory — in Eastern and Eastern-influenced works.
This may be explicitly justified in-universe when the villain the bugs herald is a Pest Controller or a Monster Progenitor, and thus explicitly called or created the swarms there to begin with. See also Atrocious Arthropods, for other depictions of arthropods as repulsive, dangerous or monstrous.
Don't confuse it with a certain cartoon rabbit heralding evil.
- Hotarubi no Tomoru Koro ni: The title translates to "When the fireflies glow". It refers to the glow of the fireflies at the night of the wake, which appear right before the characters are transported to Hell. This is an odd example, as fireflies have one of the most positive reputations of any bug out there.
- Nijigahara Holograph is an odd, Mind Screw type of story and Butterfly of Death and Rebirth is use quite frequently, but never in positive ways; they are frequently seen swarming from the tunnel where a girl was thrown down to die and another one committed suicide, and have a lot to do with a prophecy about a monster bringing about the end of the world. Their numbers and presence increase as the story continues.
- Pupa: Butterflies are a sinister symbol, being associated with flesh-eating monsters and the virus that causes them.
- In Saint Seiya: The Lost Canvas, the Specter Nasu Veronica is heavily associated with flies, controlling a horde of them to attack his enemies. He claims that the flies that descend upon a corpse do it in order to devour its soul before it can pass on to the afterlife.
- In Toriko, Tommyrod of the Gourmet Corps can breed and spit out of his mouth a variety of creepy and hostile bugs, and specifically a winged one called "Butterfly Worm" which gruesomly kills Yun's parents and is killed with a certain difficulty by the combined effort of Toriko, Takimaru and Match.
- Jago & Litefoot: In "Litefoot and Sanders", a swarm of creepy crawlies—including flies, cockroaches, bugs, millipedes and spiders—gathers around Sanders if he stays too long in one spot. He eventually says it is because they can sense his true nature as bringer of death.
- Swamp Thing: Swampy's Arch Enemy Anton Arcane is heavily associated with creepy-crawlers of all kinds, especially after one defeat forced him to rebuild his mangled body with a spider chassis. In the Alan Moore run especially, the mere fact of Swampy finding a bird corpse stuffed with bugs is treated as an omen that the bad doctor is back and up to his old tricks.
- Dungeon Keeper Ami:
- Keeper Mercury funds out that damp and heated underground dungeons make for great nests for insects to flourish, much to her chagrin. Apparently these bugs are considered a delicacy by some of her underlings, though.
- Keeper Arachne has spiders as her signature minions. Outside of the giant spiders she employs, she fills her dungeons with normal-sized one, and nearby towns notice her evil presence on the land by the sudden increase in population of spiders on their cities.
- The Babadook: One of the signs of the titular demon's growing influence is an infestation of cockroaches crawling in through a hole, though only Amelia sees them and they later vanish.
- Before I Wake: The positive manifestations of Cody's dreams, which are alight with butterflies, are contrasted with his nightmares of the Canker Man, who is heralded by a swarm of moths.
- Candyman: Bees are associated with the Candyman and are often found in the area shortly before one of his visits. This is because the original murder victim was tortured with them, and now he has taken them on as part of his Your Mind Makes It Real persona.
- Children of the Corn III: Urban Harvest: Eli's evil is worked through roaches: the corn kernels he implants in the food take form as roaches, and once his evil influence has spread far enough, the parents of one of his flock are consumed from within by them.
- Jumanji: Welcome to the Jungle: Van Pelt controls all wildlife on the island because of he stole the jewel of Jumanji. The first thing he does with his newfound power? Take all the bugs in his vicinity into his body. At one point he kills one of his men with a scorpion which crawled out of his mouth.
- The Lord of the Rings: The Fellowship of the Ring: When the first Nazgul the hobbits encounter gets off his horse to seek the ring, spiders and other insects start crawling out of the woodwork around the hiding hobbits. Similarly to the example with the basilisk in Harry Potter and the Chamber of Secrets, they are doing this to get away from Nazgul, being instinctively repulsed by his undead nature.
- The Mummy (1999): Imhotep gets a double example:
- A massive swarm of locusts is the startlingly prompt signal that reading from the cursed book has resulted in Imhotep's awakening. That's because what actually heralds his appearance per the curse is the ten plagues of Egypt, among which the locusts were the first.
- More broadly, the flesh-eating scarabs. Although they're native to Hamunaptra and present a massive threat on their own, they also answer to Imhotep due to their role in his curse: to be eaten alive by them for eternity, becoming so hungry that he eats them as well in a sick perversion of the circle of life. They can be seen crawling in and around his body several times.
- Phenomena: The heroine has a telepathic connection to insects which she uses to get their help in a murder investigation. She realizes she's in the home of the killer when she spots maggots around the place.
- The Possession: Moths are a frequent symbol associated with the Dybbuk inhabiting the box. They enter Em's body through her mouth at one point (and exit the same way) and may in fact be the actual process of possession given form.
- Prince of Darkness: One of the first signs that things are starting to go to hell is vermin showing up in the windows, crawling all around the area and even taking up the shape of one of the dead scientists to deliver a warning. It's revealed to be Satan exerting some psychic influence outside of his prison as he starts breaking out.
- In The Silence of the Lambs, the Serial Killer known as Buffalo Bill has a number of peculiar hallmarks, including sliding the cocoons of Death's Head moths down the throats of his victims - the FBI reason that the killer must be raising these moths himself, since they're not native to the United States and require very special conditions to breed. At the climax of the movie, Agent Starling's investigation leads her to a house in the hometown of the first victim, and the man that we the audience know to be the killer opens the door and invites her in. The camera lingers over a framed picture of a butterfly on the wall, and Clarice soon spots a Death's Head moth flying around, tipping her off that her host is the killer.
- Harry Potter and the Chamber of Secrets: The basilisk's growing activity results in spiders throughout the grounds fleeing the castle and heading for the forest. In an odd twist, the growing spider activity is an indirect version since the spiders were there the whole time, it's just their reaction to the events that makes them significant long enough to be mistaken as the Slytherin's monster.
- Things Fall Apart: Double-subverted, at least for any readers who are familiar with locust swarms as a bad omen or plague rather than, as the characters know them, a rain of delicious snacks. Shortly after their arrival, the village's oracle declares that Ikemefuna, the hostage from an enemy village whom protagonist Okonkwo is raising as his own son, must be killed.
- Doctor Who: The revival series and associated spinoffs have the Trickster and the Trickster's Brigade, who specialize in causing Bad Futures. One of their chosen weapons is the Time Beetle, a species of gargantuan beetle that feed on time energy by attaching to a subject and changing a critical decision in their past and thus altering the present. This is usually harmless, but when they get a hold of someone with involvement in a lot of universe-altering plots, such as Donna Noble, the dystopian results can be horrific. In Donna's specific example, something terrible happening in the altered timeline is usually heralded by someone telling her "there's something on your back", referring to the unseen beetle.
- Stranger Things: There isn't a lot of attention drawn to it, but in Season 2 all the corrupted plant life is absolutely crawling with writhing maggots.
- Supernatural: The first season has an episode called "Bugs" revolving around deaths occurring in a localized area and always involving bugs of some sort. It turns out that these murderous bugs are manifestations of an Indian Burial Ground curse — for 6 days on each spring equinox, the curse activates and kills anyone in the area as vengeance for 6 days of American calvalrymen raping, pillaging, and burning the area's Yuchi population.
- In one episode of Star Trek: Deep Space Nine, Captain Sisko has a vision of locusts descending on Bajor before heading to Cardassia. This foreshadows the Dominion invasion; Sisko's vision ends up saving Bajor, by having them sign a non-aggression pact with the Dominion.
- In the music video for “That’s What I Like” by Kelsi Luck there are scorpions crawling all over the place, and artwork of them on every object when she plans to murder her boyfriend.
- The Magnus Archives has the Flesh Hive, which manages to be both the monster and the herald. It's a manipulative Hive Mind that lives to infest and corrupt people with its bug of choice, turning them into walking nests. Jane Prentiss, the most well-known example and one of the most fearsome ones, was infested with silver worms, though it's also been known to work through flies, wasps, and ants. Not spiders, though. Spiders belong to a different Power.
- Dungeons & Dragons:
- The first sign that Kyuss, the Worm That Walks, is coming close to escaping his prison is that the vermin of Wormcrawl Island where he's sealed begin to enter frenzies of breeding and activity. They quickly become too numerous for their island and swarms of worms and centipedes begin to spill out into the rest of the world with increasing frequency. As Kyuss comes close to freedom, his power begins to affect the vermin more directly and cause them to reach monstrous sizes, transforming into powerful and aggressive monsters such as purple worms and remorhazes.
- As Ragnorra's twisted fecundity grows in power, cities begin to teem with great swarms of insects, spiders and other crawling vermin (alongside small vertebrates like bats and rats) born from the living bodies of larger creatures.
- Games Workshop: Incursions of the forces of Nurgle, the Chaos God of disease and rot from Warhammer, Warhammer: Age of Sigmar and Warhammer 40,000, are often heralded by huge swarms of flies and disease-carrying insects crawling over everyone and everything, and some of his more favored champions ride to battle atop massive fly-monsters.
- In Amnesia: The Dark Descent, a sign that you're losing your sanity to the many evils chasing you down is to start hallucinating bugs everywhere. Sometimes you might run into actual bugs too, but they're far fewer than the ones you hallucinate.
- If you choose to be a God of Evil in Black & White, your land will be filled with flies to give it a more rotten look. Conversely, if you become a God of Good, your land will be filled with cute butterflies on the day and beautiful fireflies on the night.
- Daxter: While the insect-like Metal Bugs do serve as a direct threat during the events of this game specifically, their presence definitely serves as a harbinger to the other Metal Heads getting involved should their leader Kaeden’s plan fail, making them eligible for this trope with regard to the overall Jak and Daxter franchise.
- If you recruit a giant beetle in Dungeon Keeper, it will make its nest on your Lair and fill it with living, creeping beetles.
- Fatal Frame II features the Crimson Butterfly ritual, which involves one twin strangling the other, with the victim being reborn as a butterfly. While this might seem like evil heralding a bug instead of the other way around, this is actually done to appease the Hellish Abyss. Alternatively, an outsider can be sadistically tortured and turned into a Kusabi to appease the Abyss as well.
- The Legend of Zelda: Twilight Princess:
- The Arbiter's Grounds being largely one big Shout-Out to The Mummy (1999), you'll find cobwebs everywhere and even scarabs that react to a lantern the same way they do in that film. The twist is that unlike the example below, bugs aren't reacting to the Mirror of Twilight, they simply inhabit an area of extreme evil well-documented in Hyrule's history. When you defeat the Death Sword, only the sword explodes into a puff of darkness (meaning it's a monster). The ghost itself dissolves into a swarm of locusts that escape the room very quickly.
- The Temple of Time is infested with cyclopean baby spiders of various sizes. On reaching the end of the dungeons, you find the reason these spiders are there is the Giant Spider Armoghoma, the dungeon's boss and their progenitor.
- Pathfinder: Wrath of the Righteous: The presence of Deskari, the Big Bad, is usually heralded by a swarm of locusts. Needless to say, Deskari is a major threat who wants to feed the world to his Swarm, and an Echo of his essence is a respectable bossfight for a lvl. 20 party. There is also Xanthir Vang, the Swarm that Walks, an inhumanly evil mage who found a way to transfer his mind into a swarm of insects. EVERY SINGLE NAMED CHARACTER IN THE GAME, from gods and angels to liches and demon lords, will call you out for attempting to replicate his research.
- Resident Evil: Flies, maggots, and roaches are often found in the homes of Las Plagas infectees, as the infestation gives them a taste for rotting meat. Go figure.
- Silent Hill: A recurring monster in the series is the Creeper, a dish-sized roach-like creature. They are said to be a manifestation of the town itself. The movie takes this to the next level by featuring an endless swarm of Creepers seemingly commanded by Pyramid Head.
- World of Warcraft has the aqir, a race of insects that were born from the organic matter seeping from the Old Gods when they first landed upon Azeroth. They are usually found serving the Old Gods and are almost Always Chaotic Evil, so whenever the player runs into aqir—or two of their descendant races, the qiraji and the mantid—that usually means there's Old God activity.
- Fate/stay night: The presence of Matou Zouken is always noted by the arrival of a small swarm of grotesque alien-like worms. Of course, being what he is...
- In "The Zelda CDi Reanimated Collab!" (A Multi-Animator Project based on The Legend Of Zelda C Di Games), Klaykremling's take on Goronu, a monstrous necromancer, adds bugs crawling around on his skin for creepy effect.
- In Wilde Life, the White Faced Bear is accompanied by a swarm of wolf spiders that serve as signs of his presence and go where he can't. He's mostly a good guy, however.
- In Miraculous Ladybug, the villain (named Hawkmoth in the English version) uses butterflies that transform civilians into evil villains, making them a very literal example. These butterflies are called "akuma" (Japanese for "demon"), and take residence inside a possession of the evil-ized victim, and if it's left unpurged, it will spread and multiply.
- For better or for worse, bodies have been found due to infestations of bugs centered on certain locations where they were hidden, if not the stench that attracted them. Their wiki entry describes bluebottle flies as important "forensic insects", as they lay their eggs in rotting corpses. Their eggs and the timing of their oviposition can be used to estimate time of death.