In　wireless　sensor　and　actor　networks,　when　an　event　is　detected,　the　sensor　node　needs　to　transmit　an　event　report　to　inform　the　actor.　Since　the　actor　moves　in　the　network　to　execute　missions,　its　location　is　always　unavailable　to　the　sensor　nodes.　A　popular　solution　is　the　search　strategy　that　can　forward　the　data　to　a　node　without　its　location　information.　However,　most　existing　works　have　not　considered　the　mobility　of　the　node,　and　thus　generate　significant　energy　consumption　or　transmission　delay.　In　this　paper,　we　propose　the　trail-based　search　(TS)　strategy　that　takes　advantage　of　actor’s　mobility　to　improve　the　search　efficiency.　The　main　idea　of　TS　is　that,　when　the　actor　moves　in　the　network,　it　can　leave　its　trail　composed　of　continuous　footprints.　The　search　packet　with　the　event　report　is　transmitted　in　the　network　to　search　the　actor　or　its　footprints.　Once　an　effective　footprint　is　discovered,　the　packet　will　be　forwarded　along　the　trail　until　it　is　received　by　the　actor.　Moreover,　we　derive　the　condition　to　guarantee　the　trail　connectivity,　and　propose　the　redundancy　reduction　scheme　based　on　TS　(TS-R)　to　reduce　nontrivial　transmission　redundancy　that　is　generated　by　the　trail.　The　theoretical　and　numerical　analysis　is　provided　to　prove　the　efficiency　of　TS.　Compared　with　the　well-known　expanding　ring　search　(ERS),　TS　significantly　reduces　the　energy　consumption　and　search　delay.　©　2017　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.