That is, a youngster who fancies older people?
How about geri-phile?
Ashton Kutcher?
or better yet, gerophile
I think the term for “sexual attraction to the elderly” is gerontophilia. (Don’t know if this precisely meets the OP’s case … )
A geri-phile, of course, is someone who’s sexually attracted to Ginger Spice.
Umberto Eco wrote a hilarious parody of Lolita that he called Granita. In his version of the story, a young man falls in love with an old lady. It would seem that the sight of her marbled flesh, glimpsed through a window as she removed her stockings, drove him wild with uncontrollable lust. When he runs away with her, he has to travel by bicycle (he doesn’t have a driver’s license yet) and pedals away with “Granita” holding on for dear life. The story appears in Eco’s anthology Misreadings.
“MILF-Hunter”?
Ew.
Seriously, I’m not sure, but if you’re really interested in the subject 
then go watch Harold & Maude
Good movie by the way
In most cultures there is a clear definition of childhood or at least age of legal minority. Where is the line between say, someone like me who has a wife 9 years older, and a 20 year old crusing for chicks at the old folks home?
In the gay community—at least, 25 years ago—they were known as “wrinkle queens.”
Is the OP talking about teenagers or young adults who are attracted to older people? Or pre-pubescent children who are precociously sexualized and seek encounters with adults?
The former.
That would be, “A High School Student.”
Well, one who had a TOTAL BABE for a Spanish teacher anyway…
And I had the hots for my English teachers in grade nine AND grade ten…
…but I don’t think that a post-pubescent teen lusting after an older man or woman is the precise opposite of a pedophile. A pedophile lusts after pre-pubescent children, not young men and women.
I’m more inclined to agree that the opposite of a pedophile is one of Lumpy’s “pre-pubescent children who are precociously sexualized and seek encounters with adults”.
Does this ever occur?
Indeed… a teenager or young adult who lusts after older people would be a reverse ephebophile.
Unfortunately, it happens among survivors of sexual abuse… Whether they were sexualized pre-pubescently or pubescently… At least among the Male Survivors I know…
When the only attention you’ve gotten (whether positive or negative) is through sex with adults, you tend to seek it out again… 
Uh, wouldn’t “jailbait” be the right word?