The series finale, “Changing Nature,” aired on July 20, 1994, and the episode began with the Sinclair family gathered at a picnic awaiting the annual return of the bunch beetles. The beetles, much to the disappointment of the family, never show.
We learn, in a bit of foreshadowing, that the reason the beetles never returned was that they had been eradicated after the dinosaurs had, irresponsibly, built a plastic fruit factory over their swamp breeding ground.
The beetles played an important role in the ecosystem of Pangaea, by feeding on a type of climbing vine. Without the beetles, the vines began growing out of control.
Of course, Earl was put in charge of an environmental task force responsible for solving the vine problem.