Michael Fabricant posted the insult to an account which reportedly belongs to a teenage girl.
An argument had begun on the social network when the user accused Mr Fabricant of neglecting a town in his constituency of Lichfield.
She had mocked the Tories’ campaign slogan at the last general election – rebranding “strong and stable” as “weak and wobbly”.
Mr Fabricant, 67, replied: “Says a complete t*** who seems unaware that there is no vote this year in Burntwood! And I neglect no part of my lovely constituency. That’s why I’m loved!!”
The account he replied to, @Darcycanfly, is believed to belong to a local girl called Darcy Norgate.
She has called for the MP to apologise, as the tweet contained vulgar slang for a woman’s genitals.
But Mr Fabricant has said he did not know what the word meant, writing: “I think of it as ‘twit’.”
He also accused the teenager of being a “professional snowflake” who was feigning offence, and wrote: “For all I know [Darcy] is a Russian troll in St Petersburg – there are plenty of those.”
The MP went on to write that Twitter was “not like Facebook” and “not for those who are easily offended” – adding that “Momentum trolls from Glasgow and elsewhere purport to comment on events… while knowing nothing about the area”.
“If you are constituent making a serious point, you will always be treated seriously. But not if twitter location says ‘Wonderland’,” he said.
Earlier this year, 13 Russian nationals were indicted in the US for their connections to the St Petersburg-based ‘Internet Research Agency’ which is accused of attempting to influence the US elections through Twitter trolls.