Answer:

PEST

AnswerCrossword Clue
PESTDennis, to Mr. Wilson
PESTAnnoying one
PESTBurr under the saddle
PESTInsecticide victim
PESTNuisance
PESTAnnoying person
PESTExterminator's quarry
PESTRoach or slug
PESTRoach, for one
PESTRoyal pain
PESTKid brother, sometimes
PESTPain in the neck
PESTTerminator's target
PEST21A, for one
PESTBlack Flag victim
PESTExterminator's target
PESTNo-see-um, for one
PESTNudnik
PESTSwattable sort
PESTSource of annoyance
PESTYounger sib, maybe
PESTUnwelcome guest
PESTUnwelcome visitor
PEST"Shoo!" addressee
PESTReal annoyance
PESTRaid target
PESTThorn in the side
PESTTelemarketer, to many
PESTThorn in one's side
PESTBother
PESTFly, e.g.
PESTHorticultural woe
PESTImp
PESTHeckler, e.g.
PESTKid brother, at his worst
PESTAnnoyance
PESTBothersome kid
PESTPain, so to speak
PESTBrat
PESTGnat or rat