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• Yellow - a tall dimwitted and happy-go-lucky yellow-colored caterpillar with 1 antenna who has a contentious friendship with Red. Although usually he obeys Red, he loses his mind in front of food. He changes color from yellow to brown and he grows dark green shades around his mouth when feeling extreme emotions.
• Red – a short hot-tempered and greedy red-colored caterpillar. Red has tried to steal Yellow's love interest, Pink, but he always ends up alone. He shrieks, shouts and screams when in anger, fear, frustration and in a horrible panic.^[2]

Recurring

• Violet – An oversized purple ghost slug. He has an exposed inner body and roar, showing his sharp teeth.
• Brown – An dung beetle that gathers dung. To him, dung is a treasure, though it makes his breath stink. He hates it when other insects touch his dungball. He has a long strand of hair on his right cheek.
• Black – A horned atlas beetle that has great strength and is usually punching a cocoon (which he uses as punching bag). He's aggressive and will beat up whoever he thinks is messing with him. In "Black's Back" he turns out to be a slug wearing beetle armor.
• Rainbow – A lazy snail with a red and green shell. When in his shell, he moves slowly, but under that, he has a muscular human-like body and can function as humans do.
• Pink – A pink-colored caterpillar with two antennae. She loves Yellow and Yellow loves her as well, but her presence often causes conflict between him and Red, who has a one-sided crush on her. She hides a great strength behind her cute, beautiful face.
• Ivory - A stick bug with brown skin, Ivory has a very thin body with brown skin color. He has black eyes and darker colored areas by his eyelids. He has 2 antennae and little pink studs on. His girlfriend is Cocoa.

Minor

• Blue – A housefly that has numerous smells. Nobody can get close because of his repugnant smell. He often feels gloomy and lonely because nobody can approach him.
• Navy – A deep-sea fish appears when the sewerage is sunk. He appeared as a goldfish. When Red and Yellow threw him into a sardine can full of warm water, he changed into a deep-sea fish which is often seen whenever the sewer floods. He has a good enough appetite to eat up the caterpillars and other insects.
• Venus flytrap – A venus flytrap who eats up anything on the ground. In season 1, he is an enemy to all insects because he tries to swallow the other insects when he encounters them. But he is weaker than Violet. He appears to have a menacing set of teeth.
• Green (also known as Frog) – A frog which often appears in the sewer, is sensitive, and tries to monopolize all power by eating insects and larvae. He is several times bigger than other normal frogs. He escaped from the sewer and went into the house where Red and Yellow lived in season 2. In season 3, he lives on the streets along with Grey & the Silvers.
• Bee – A honey bee who collects honey. She stings when someone touches the honey that she collected or makes her angry.
• Maroon – A dachshund who wears a blue and yellow sweater who only appeared in season 2. He attacks when he sees moving things. He buries his valued bones in the ground and is quite temperamental. In "Whistle", he does certain things when he hears certain whistling.
• Prussian – A blue parrot which appears in season 2. He observes other friends and gives a sardonic laugh before attacking. He is also a predator to the caterpillars. "Nanta" revealed that he used to live in the Amazon rainforest as a hatchling.
• Prism – A chameleon which appears intermittently in various areas of season 2, such as the living room, bathroom, rooftop, and even bedroom; he suddenly appears and attacks Red and Yellow without reason.^[2]
• Ephemera – A mayfly who appears in the titular episode. Red has a crush on her, but she dies quickly due to the lifespan of an average mayfly.
• Bomber bug – A bombardier beetle which bombed Yellow, Red, and Brown in the episode "Bomb Bug" in Season 2. He has the ability to bomb a place with acid which comes out from his bottom. He usually does that when he's angry, sad, or feeling disgusted.
• Grey – A rat that appears in season 3 and 5. He is an enemy to all caterpillars in this season.
• Silvers – A pigeon duo using food scraps (a banana peel and a carved-out half watermelon) to protect their super reflective heads from the sun, they are enemies of the larvae. Each pigeon communicates with one word, "Yah" for the pigeon wearing the banana peel, and "Huh" for the pigeon wearing the carved out watermelon. These pigeons only appear in Season 3.
• Cocoa - A creature of an indeterminate species that is Ivory's girlfriend.
• Mite - A baby mite who Yellow initially adopts, but turns out to parasitically prey on Yellow and the others. Then Yellow leaves it in a zoo.
• Mud - A pair of fish. They live underground under the sands and can slap each other with their fins.
• Booby - A Blue-footed booby bird. He met the larvae when they landed on his island.
• Mango - A caterpillar Red has fallen in love with. When she first meets Red, she couples with him. When Red and Yellow escaped the island, she knew she had to leave her home to find her boyfriend, Her name is a fruit called a mango.
• Chuck (voiced by Eddy Lee) - A human. He is the first character who can speak properly, although previously other characters occasionally spoke on occasion if it fits the scene.
• Clara - A seal that Red and Yellow befriended. She is playful and charming and has the same name as Chuck's girlfriend.
• Whale - A whale who appears in season 4.
• Crabsformer - A crab that accidentally ate an unknown object that turned him into a robotic crab. He has a crush on a lady crab, however, she and the other crabs are scared of his powers. This character appears in season 4.
• Malt - A dark grey tabby cat & the assistant of the bald bug capturing scientist who plans to use the captured bugs for his invention that uses bugs to create a hair-growth solution to restore his hair. He first debuts in Larva Pendant.
• Magenta - A young magenta-colored caterpillar who was born in season 5 from Yellow who accidentally ate a pink egg, She would find care with Yellow and Red, who grew to care for the newborn. Eventually, she would metamorphose into a pink honey bee.
• Big Brown - A easygoing pig-nosed turtle who is often seen meditating. He appears in season 5. He rarely gets upset and is a very good sensei, but he will stand up for his friends, should the need arise.
• Grizzly - A moth, that is as sneaky as he is greedy, can be invisible, and blind others with his smoke should his cover be blown. Despite this greed, he can protect others should push come to shove, and he has fallen in love with one of the bees that work in the hive. He appears in season 5.
• Mauve - An owl who is very protective of her little one, Tan. She may be fierce should anyone hurt her little one, but she means well, and while they got off on a rocky start she starts to think of Yellow, Red, and Magenta as friends. She would appear in season 5.
• Tan - Muave's hatchling who became friends with Magenta, and like her, he would grow as well he would appear in season 5.

Series overview

Season 1 - Grate (2011)

Season 2 - House (2012)

Season 3 - New York (2014-15)

Season 4 - Larva Island (2018-19)

Season 5 - Family (2023)

Netflix films