'Urchin' or 'Hurgeon' is a dialect name for a hedgehog, and small bogies or pixies often took hedgehog form and were therefore called 'urchins'. It will be remembered that Caliban was tormented by urchins at Prospero's command.

...then like Hedg-hogs, which

Lye tumbling in my bare-foote way, and mount

Their pricks at my foot-fall...

'The Tempest' by Mr. William Shakespeare

'Urchens' are mentioned by Reginald Scot in his list of frightening spirits. The name came into use for small, impish boys and passed out of common use for fairies.