The material below is Open Game Content from a 3PP Source
School abjuration; Level bard 4, cleric 4, druid 4, ranger 3, witch-4wfg 4
Casting Time 1 standard action
Components V, S, DF
Range 10 ft.
Area 10-ft.-radius emanation centered on you
Duration 10 min./level (D)
Saving Throw none or Will negates; see text; Spell Resistance yes
An invisible barrier holds back vermin. A vermin with HD of less than one-third your level cannot penetrate the barrier.
A vermin with HD of one-third your level or more can penetrate the barrier if it succeeds on a Will save. Even so, crossing the barrier deals the vermin 2d6 points of damage, and pressing against the barrier causes pain, which deters most vermin.