gadfly

IPA: gˈædfɫaɪ

Any dipterous (“two-winged”) insect or fly of the family Oestridae (commonly known as a botfly) or Tabanidae (horsefly), noted for irritating animals by buzzing about them, and biting them to suck their blood; a gadbee.
(figuratively, also attributively)
A person or thing that irritates or instigates.
(specifically) A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.
Synonym of gadabout (“a person who restlessly moves from place to place, seeking amusement or the companionship of others”)
(derogatory, slang) A person who takes without giving back; a bloodsucker.

Examples of "gadfly" in Sentences

There's a time to be the gadfly.
The actual gadfly page is about the insect.
He got to the point of being called a gadfly.
Q: You've been called a gadfly, a consumer activist.
Even to the point of being called a gadfly, he kept nagging.
Clarke was described as a gadfly of Harlem intellectual life.
The second argument is that his career as a gadfly is notable.
The taxonomy of the gadfly petrels is being reformed at the moment.
Being a gadfly is certainly a role, and occasionally a helpful one.
This is a list of the birds that belong to the group gadfly petrels.
However, Diefenbaker proved a gadfly and an annoyance to Mackenzie King.
As for the Gadfly link, I'll get rid of it for now and consult other editors.
And sometimes the gadfly is off base and really doesn't understand what is going on.
History shows that once in a while even a so-called gadfly has been able to effect change.
The Alaskan resident – now being referred to as a gadfly – criticized where she felt it was due and gave credit where it appeared there should be some.
Boris Pincus, a former Queens resident who serves as Republican District Leader of Assembly District 45 in Brooklyn, has long been known as a gadfly within the Bukharian community who is biting in his criticism of the communal leadership.