WEST LAFAYETTE, Ind. - That mole is burrowing along under your grass and through your garden, but is there any redeeming value to the critter's industrious search for an earthworm meal?
"Most people don't realize that moles are not rodents, but insectivores," said Tim Gibb of Purdue University's Plant and Pest Diagnostic Laboratory. "Their diet consists of small invertebrate animals - insects and worms - that live underground. Ninety percent of their food is earthworms."
Moles perform some useful tasks, including helping to aerate soil and eating some insects that are pests to plants, he said. They do not eat bulbs or garden plant roots.
While moles will eat grubs, the old tale that grubs will attract moles is not true, said Gibb, who is also a Purdue Turfgrass Integrated Pest Management team member.
"We only have grubs for a certain portion of the year, generally in the fall," he said. "So we know moles are feeding on something else for the most part."
Since moles are mainly interested in chowing on earthworms, they follow them, Gibb said. When the ground is wet and not frozen, earthworms tend to be just under the top layer of soil, so moles dig the tunnels they use to hunt for food in the same areas. This causes long humps that are easily seen. When the ground dries out in summer and freezes in winter, earthworms go deeper and the moles follow.
The high-metabolism, furry creatures are only 6-8 inches long and are eating and active year-round, day and night. Moles use their strong forearms with front-facing paws and long, sharp claws to dig as much as 100 feet of tunnel per day in their quest for food.
The silvery-gray, almost down-soft animals live underground their entire lives except for a brief period when they first enter adulthood and leave the nest to find their own homes. Since they are subterranean, moles' keen senses of smell, hearing and touch compensate for their near blindness.
The moles' underground lifestyle increases the difficulty of halting their destruction of manicured lawns and gardens, Gibb said. But because males are quite territorial, usually not more than two or three moles will be in the same area except when a female has a nest of young.
Broods of three to five young are born in the spring after a four-week gestation period. The mother cares for them for four or five weeks in a nest that is 4-16 inches underground.
Although most people consider them pests, moles are fascinating creatures because they are among the oldest mammals, Gibb said.
A member of the mammal order of Insectivora, commonly called insectivores, moles developed in North America about 100 million years ago during the cretaceous period of the Mesozoic Era. It's believed that moles developed even earlier in Europe before migrating.
Many mammals eat insects and other invertebrates, but insectivores are the only order that feeds almost entirely on them, Gibb said.
The order of Insectivora now includes six living families with about 400 species spread throughout most of the world, except for Australia and the northernmost part of South America. These include shrews and hedgehogs. Moles live in Europe, Asia and North America and are found mainly in woodland areas.
Gibb said the moles common to Indiana are mainly the Eastern species that has a long, thin snout. Star-nosed moles also are found in northern Indiana, but these tend to be more common in the western United States.
But despite the differences among species, all moles share the same loves - insects, worms and digging.
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