Control of Orchard Voles with Broadcast Baits1

Excellent control of pine voles ( Microtus pinetorum ) and meadow voles ( M. pennsylvanicus ) was achieved using several commercially formulated, pelletized anticoagulant baits as a single broadcast treatment. A new pelletized formulation of zinc phosphide (Zn 3 P 2 ) was shown to kill about 30% more voles in both hand-placed and broadcast field trials when compared to one of the commercially available, surface-coated 2% Zn 3 P 2 corn and oat formulations. Hand-placed cellophane- or plastic-packaged rodenticides were shown to be effective. Packs hand-placed under 2 types of covers (cinder blocks or split tires) gave equivalent control. Since about 5% of the hand-placed packs were not opened where voles were known to be present, a low but residual population was sufficient for repopulation of the orchard.