Hoppity the Grasshopper, after a period spent away, returns to an American city (Manhattan, New York). He finds that all is not as he left it, and his insect friends (who live in the "Lowlands" just outside of the garden of a cute bungalow belonging to down-on-his-luck songwriter Dick Dickens and his wife Mary) are now under threat from the "human ones," who are trampling through the broken-down fence, using it as a shortcut.

Insect houses are being flattened and burned by cast away cigar butts. Old Mr. Bumble and his beautiful daughter Honey (Hoppity's sweetheart) are in grave danger of losing their Honey Shop to this threat. To compound their problems, devious insect "property magnate" C. Bagley Beetle has romantic designs on Honey Bee himself, and, with the help of his henchmen Swat the Fly and Smack the Mosquito, Honey is tricked into marrying the Beetle for the good of the insect community.

Hoppity discovers that the Songwriter and his wife are waiting for a "check thing" from the Famous Music publishing company for the songwriter's composition, "We're the Couple in the Castle." With this money they can save the whole bug community. But C. Bagley Beetle and his henchmen "steal" the check, and the Dickens house is foreclosed. Days pass and with nothing improved nearly everyone in the lowlands loses faith in Hoppity's claim. To make matters worse the Dickenses lose their home when a skyscraper is built on the site. Mr. Beetle can force everyone to pay his exorbitant prices -- until he finds out that the building will be on his property too. Realizing that Hoppity was nearby and overheard him, he seals Hoppity inside the envelope that the Dickens' check came in, hiding it in a crack in a wall.

Construction begins while everyone is at the wedding of Beetle and Honey; a weight from a surveyor's level that rips through the chapel causes the terrified bugs to flee back to the Lowlands (not realizing the whole parcel is endangered by the construction crew). Hoppity escapes when the construction crew demolishes the wall, freeing the envelope. Hoppity comes to Honey's rescue, battles Beetle and his henchmen, and wins.

Hoppity tells everyone what happened and manages to get the check to Mr. Dickens. "We're the Couple in the Castle" becomes a massive hit. Meanwhile, Hoppity leads an exodus from the Lowlands to the top of the skyscraper, where he believes the Dickens' have built a new home and invited the bugs to live there. They get to the top, which at first appears to be barren, but the young bugs discover the Dickens have built a new penthouse with a "Garden of Paradise" just as Hoppity had described. Honey and the rest of the Lowlanders live there happily ever after in their new home. And as Ambrose looks over the edge, he remarks, "Look at all the human ones down there. They look just like a lot of little bugs!"