A superhero team made up of five insects solve problems in the minuscule town of Yardley, using a discarded milk carton as their secret base.
- Jason (Mighty Bug) (voiced by Bill Lobley) - A blue beetle whose superhero identity and the leader, Mighty Bug gives the team its name. His superpower is "mighty vision."
- Antny (Super Antny) (voiced by Nancy Giles) - A small purple ant whose superhero ability is the "power to grow."
- Lizzy (Invisilizzy) (voiced by Ashley Paige Albert) - An orange honeybee who can become invisible.
- Catybug (Go Girl) (voiced by Nancy Giles) - A ladybug with a jet pack, enabling her to fly at high speeds.
- Parnell (voiced by Jonny Belt) - A timid earthworm with excellent driving skills. His superhero name is the same as his true identity.
- Princess Bug (voiced by Cree Summer) - a light orange beetle who's a princess.
- Mr. Bigsnail (voiced by Chris Phillips) - An enormous garden snail with a deep voice. He sends the Mighty Bug 5 on missions.
Seven episodes of the series were produced. Only six aired on television, with the pilot left unaired.
- Pilot - A "pinch bug" disturbs bugs all over Yardley.
- The Litterbug Blast - A villain known as "The Litterbug" throws garbage across Yardley.
- Mighty Big Bridge - The captain of a party boat needs help fixing a broken bridge.
- Police Chief Birthday - The sheriff of Yardley's police force celebrates his birthday.
- Rhinoceros Beetle - A purple rhinoceros beetle blocks a tunnel, causing a traffic jam.
- Noisy Robot - A professor builds a giant insect-like robot, but cannot turn it off.
A digital game on NickJr.com titled "The Litterbug's Grime Spree" was released in 2005, based on the first short, "The Litterbug Blast." Players of the game must follow the Litterbug across various locations in Yardley, such as the beach and playground, to pick up garbage he leaves behind. Mr. Bigsnail guides players through the game's controls.
From 2005 until 2007, NickJr.com allowed members of the site to send an animated e-card based on Mighty Bug 5 to others via email.
Activities such as the printable coloring pages of the characters were also available on NickJr.com while the shorts were still airing.