While it may seem amusing that a frog would find its way into a toilet, if you are constantly having to remove an army of frogs from the toilet bowl or around the rim, it quickly can stop being funny. Although you might think these web-footed amphibians are swimming up through the sewer lines, it may surprise you to learn that the type of frog typically found in toilets is actually a tree frog.
Cut tree limbs away from the roof of the house with a tree trimmer or chainsaw. Tree frogs normally climb up trees and jump from the branches onto the roof of the house to warm themselves on the shingles.
Mount a screen with 1/4-inch mesh over the toilet vent on the roof of the house -- plumbing stack covers are available for typical pipe diameters. Once a frog is warm, it typically will move to someplace cooler, such as the inside of a toilet vent. Unfortunately, once the frog jumps into the vent, it will fall downward, go through the vent pipe, and find its way into the toilet.
Turn outdoor lights off at night to help keep bug populations down. Lights attract bugs, which in turn attract frogs. Without a steady food supply, the frogs will go elsewhere.