Related Clues:

• Spammer, for one
• Mosquito, e.g.
• Unwelcome visitor
• Air-breathing arthropod
• Exterminator's quarry
• Constant interrupter
• Persistent annoyer
• Bothersome one
• Entomologist's interest
• Bothersome type
• Genuine nuisance
• Telemarketer, perhaps
• Brat or bug, e.g.
• Gnat or brat
• Mole, to a gardener