Related Clues:

• Nits and gnats
• Younger siblings, at times
• Ones that have infested four puzzle answers
• Unwelcome company
• Lapdogs harbour small bugs
• Anagrammatic intruders in this puzzle's longest Across answers
• Invaders of crops
• Mosquitoes and mice
• Flies in the face of someone?
• Flea and fly, for two
• Ants and gnats, e.g
• Gnats and rats
• Bugs that bug
• Bedbugs and such
• Bothersome people