Wire wool has long been a useful tool for the professional pest controller. Wire wool is very useful for filling holes where rodents may gain access. Rodents will not chew wire wool unlike other fillers.
It can be used as a temporary block to gaps around pipes and cables. Other fillers even a mortar repair, may be chewed or pulled out by rodents using their strong, hooked, front teeth. Rodents, however will not attempt to chew through wire wool. It can be pushed into position for a temporary repair or can be used in conjunction with other mortars and fillers to achieve a more permanent repair that rats and mice will be unable to break through.
PFH • Professional Tip
When using wire wool it is tempting to tear pieces off to size from the wire wool pack. Wire wool strands are razor sharp and can easily cause nasty cuts and wire 'splinters'. If you do tear pieces from the roll do so over a dustbin to prevent loose wire fibers getting in to flooring and feet.
Do not store wire wool near to even the smallest or lowest voltage battery. Even this low voltage, will cause the fine filaments of wire wool to heat up to the point that they may ignite.