Bundimuns are household pests that are found worldwide. They look like a greenish fungus with eyes and have an unknown number of spindly legs which they will use if alarmed.
Bundimuns feed on dirt, and their secretion, in diluted form, is used in some magical cleaning solutions (FB).
An infestation of Bundimuns can destroy a house, as their secretions rot away the foundations. A scouring charm will get rid of most minor infestations. Severe infestations require intervention from the Department for the Regulation and Control of Magical Creatures (FB).
"Bundimun" is a multiple choice answer on the Grade 1 WOMBAT test, in a question about household pests (JKR-W1).
From the Web
"Bundimun" on the Harry Potter Wiki