In the film, the title group (comprising Leo, June, Quincy, Annie) meet a little monarch caterpillar. The caterpillar sings a song called "Buggy Wuggy". Annie sings to it, Leo conducts to it, while the Little Einsteins sing it. They then discover a green truck with a tree on it. When the caterpillar gets into the truck, he waves goodbye to the Little Einsteins, as the caterpillar's waving dies down, the truck gets bumped under a little hill, which causes the caterpillar to fly out of the back of the truck. Annie calls out to stop.