Voles, mice, and squirrels have a particular fondness for tender spring flower bulbs. You can discourage these pests from dining on your tulips, hyacinths and crocuses by sprinkling in some all-natural Bulb Insurance when you plant. Made from coarsely-ground oyster shells, Bulb Insurance forms a sharp-edged barrier that burrowing rodents will think twice before crossing. To repel pests and promote brilliant color in one easy step, try Bulb Insurance Plus. It\'s a mixture of ground oyster shells and all-natural fertilizer that we developed with help from some of the nation\'s leading bulb suppliers. Each 5 lb bag protects up to 80 bulbs. Slow-release nitrogen and other nutrients ensure colorful blooms and overall plant health. Gardener\'s Supply Exclusive