Some interesting tidbits from this Marketing Charts article:
"While Facebook’s appeal is weakening, Instagram’s is growing quickly. In fact, Instagram is now tied with Facebook as the second-most important social network among teens, at almost double its share of respondents (12%) from the year-earlier period."
"Nevertheless, the same Pew survey found that Twitter’s adoption rate among teens had grown by 50% in just one year. The Piper Jaffray study results also indicate that teens believe that Twitter impacts their purchases more than Facebook and Instagram."