Ferris drew the referee's attention to the incident during the 23rd minute of England's crushing 6 Nations win over Ireland but Nigel Owens admitted he hadn't see anything and therefore wouldn't be taking any onfield action.
Hartley has been charged under the law regarding "acts contrary to good sportsmanship" and could be banned for as long as four years if found guilty.
The lowest suspension for biting is 12 weeks, while the entry point for a top level offence is 24 weeks.
A 12-week ban would end Hartley's domestic season prematurely and also rule him out of England's summer tour of South Africa, which includes Test matches against the Springboks on June 9, 16 and 23, while an even longer suspension could impact on his hopes of making the 2013 Lions tour.
Hartley previously served a six-month suspension for eye gouging when playing for his club side against London Wasps back in 2007, with critics having continued to question the New Zealand born star's discipline despite an improved record over the past five years.
No date has yet been set for Hartley's hearing, which will be heard by an independent 6 Nations disciplinary committee, but Hartley cannot play in the meantime.
The Rugby Football Union have chosen not to speak publicly about the allegation, expect to confirm that they have been told of Hartley's citing.
"The England management have been formally notified about the citing of Dylan Hartley and will not be making any comment until the resolution of the disciplinary hearing," read an RFU statement.