Pity no one can help with the iPhone app, though - thta would have been sweet!
An insatiable brat who never ceases to be hungry, particularly thought to be a fairy changeling substituted for a real child.
From the German kielkrpf, of uncertain etymology.
1652 H. Bell Luther's Colloq. 387: Near unto Halberstad, was a man that also had a Killcrop, who sucked the mother and 5 other women drie; and besides devoured very much.
1681 T. Flatman Heraclitus Ridens No. 28: They may talk of+Canibals, Man-eaters, Killcraps, and the Devil and all.
1836 W. Irving in Life & Lett. (1866) III. 90: Those little fairy changelings called Killcrops, which eat and eat, and are never the fatter.
1843 Southey The Killcrop xvi: If killcrops look like children, by what power Know you they are not?
If my mother had have known what a killcrop was when I was a teenager, she definitely would have called me one for my barathrum of a stomach!