The tire halves are then distributed one per tree or one every 10 yards throughout the area. Discontinue use if nontarget animals are coming into contact with bait. Pine voles are not as active aboveground, so bait should be placed directly in runways and burrow openings at two to four locations under infested trees. If runways and burrows cannot be found, roofing shingles, boards, or other objects placed on the ground at each placement site provide voles with shelters where they may build tunnels or nests. Place bait under these shelters after they have been in place for several weeks.
Timing also influences the success of control programs.
Wet weather reduces the effectiveness of rodenticides, so apply baits when weather is likely to be fair and dry for at least 3 days. Baits are most effective when naturally occurring foods, such as green vegetation and fruit drops, are limited. Late fall is an important time to bait voles because it serves to reduce populations before the onset of winter, when vole damage is most severe and snow cover precludes rodenticide use. When winter survival is high, baits should be applied in the spring before the breeding season and before renewed growth of groundcover diminishes bait acceptance. Most rodenticide labels stipulate that bait can only be applied during the dormant season, after harvest, and before bud burst in the spring.