A former school support worker has admitted posing as a teenage girl on a social networking site to entice young boys to send him indecent images.
Brian Syme, 32, from Alloa, targeted more than 90 victims between January 2006 and December 2009.
Some of the boys were pupils at schools in Clackmannanshire, where the qualified teacher worked.
Syme was placed on the sex offenders register and was remanded in custody until sentencing next month.
The High Court in Glasgow heard he had set up fake profiles of himself on the internet and would chat to his victims before sending them naked pictures of a teenage girl.
He then asked the boys to send him indecent pictures of themselves and encouraged them to perform sex acts using a webcam.
The support worker also had a file named "locals" stored on a pen drive, which contained images of boys he had targeted in his local area.
He was eventually caught during a Central Scotland Police investigation and admitted to a string of sex offences in court, including using lewd and indecent behaviour towards youngsters and possessing indecent images of children.
Prosecutor Gillian Wade told the court police raided Syme's home in December last year and found 283 indecent photos of children and 107 indecent videos.
Ms Wade said: "The accused confirmed that he had set up fake profiles on his Bebo pages in the names of Niki D and Beth J.
"On the fake profiles he portrayed himself as 16 to 18 year old Scottish females and adopted their character and persona, allowing him to engage and chat to teenage boys under false pretences."
'Sickened and disgusted'
Syme told officers he targeted boys aged between 14 and 20.
Ms Wade added that a number of the boys targeted by Syme had been taught by him and were "sickened and disgusted" when they found out it was him.
During his police interview Syme told officers that he did not have a sexual interest in children and had done it out of curiosity.
Ms Wade added: "He said that he knew what he was doing was wrong and kept planning to stop but never quite managed it.
"He related it to being like a smoking addiction."
Judge Lady Stacey deferred sentence until August for background reports.