What Is Digging in My Mulch Every Night?

To many gardeners, organic mulch is a moisture-retaining, soil-improving and weed-deterring necessity. To raccoons and other nocturnal creatures, it's a place to look for food. In doing so, they never leave an expanse of mulch as neatly manicured as they found it. On the upside, their digging habits, like fingerprints at a crime scene, provide strong clues to their identities.

Within every pile or layer of organic mulch lies an entirely different world. It's populated by various creepy-crawlies, three of which are shrimp-related arthropods. Millipedes sport dozens of legs on 1/2- to 3/4-inch bodies. They share the space with pillbugs -- also known as roly-polies -- and sowbugs, and all three feed on decaying vegetation.

Spiders also nest beneath mulch, along with fat, C-shaped white grubs, the offspring of the bumble flower beetle.

Covering newly planted flower bulbs and seeds with mulch won't save them from digging claws. Fall-planted, spring-flowering tulips (Tulipa spp.) -- grown in U.S. Department of Agriculture plant hardiness zones 3 through 9, depending on the variety -- are especially vulnerable.

Raccoons, skunks and armadillos regard arthropods, spiders and grubs as filet mignon and venture out under cover of darkness to dig for their dinners. Skunks and raccoons press their noses against the mulch, scraping with their forepaws when they smell something promising.

They leave behind shallow, cone-shaped indentations measuring 3 to 10 inches across. Raccoon tracks resemble tiny handprints in the soft soil around the mulch.

Don't confuse raccoons and opossum tracks. Opossums also hunt for insects at night, but they don't dig because their paws are too soft.

Although most common in the South and Southwest, armadillos have invaded gardens further north to search for insects and grubs. Armadillos use their long, pointed snouts to root through mulch, leaving holes up to 6 inches deep and 3 inches wide.

Cursed with poor eyesight and blessed with long, razor-sharp claws, armadillos meander through the mulch and leave winding, hole-lined paths.

For mice, nighttime is the right time to tear up mulch in search of bulbs or seeds. Mice sleep during the day in underground burrows or in above-ground garden nests of leaf mulch.

If the damage shows up right after you planted flower bulbs, and scraps of bulb "paper" or bits of chewed bulb tissue litter the surface, suspect mice. An acute sense of smell also lets mice locate seeds buried 6 inches deep. Sunflower seeds are a favorite.

Small holes showing up in mulch the morning after you planted seeds are mouse calling cards.

Voles, also known as meadow mice , love to burrow beneath the mulch, creating networks of tunnels., They also steal bulbs, but they do it without leaving surface clues.

Some dogs find the chocolaty aroma of cocoa-bean shell mulch irresistible. Members of the local canine set stop by to scoop up dessert during their nightly neighborhood rounds. Eating enough of it causes vomiting, diarrhea or worse.

As natural night prowlers, cats often use mulched garden beds as latrines. If the first one does, others in the neighborhood are likely to stop in and leave a return deposit. They use their front paws to pile mulch over their efforts, usually from several directions.