Bug Off!

Tyler and his big sister, Krista, can't stand each other! Tyler is a master manipulator and constantly gets Krista into trouble. When Krista angrily wishes Tyler would just turn into a bug and buzz off, she gets her wish courtesy of Mrs. Pickle Nickle, an alien babysitter, who has been sent to Earth to learn how humans get along. Yendor shows up and tries to kidnap Tyler, the bug, and take him to their planet as evidence of Pickle Nickle's incompetence. It's a race to the finish as Krista goes searching for her missing bug, er brother, and get him back to normal before Mom and Dad get home! (official distributor synopsis)