Meet the Garden Good Guys: Snakes, Toads, Spiders, and Batscomments (4) March 27th, 2009
by Des Kennedy
from issue #24
With all the talk of wildlife gardening nowadays, most of the attention goes to birds, butterflies, and beneficial insects. But an equally compelling case can be made for enticing reptiles, amphibians, arachnids, and bats into the garden.
While the snake, the toad, the spider, and the bat can improve almost any garden, each is burdened with an unsavory reputation. Secretive and reclusive in habit, all are, or have been, objects of human fear and loathing, despised as dirty and dangerous. All four were once reviled as the familiars of witches, assisting evil crones in their sinister business. Small wonder that butterflies and hummingbirds rate higher on the wildlife gardening agenda.
But once we emerge from the dark shadow of superstition, we see the true value of these four creatures. All are superb pest suppressants. Yet as urbanization advances across the landscape, some of them are threatened. Increasingly, they are creatures in need of sanctuary. Furthermore, I’ve come to believe that the more elements of a local ecosystem a garden contains, the more it becomes a healthy and desirable place. We may not want to throw the gates open to thieving raccoons or ravenous deer, but for the most part, these four ugly pugs will do no harm and an immense amount of good.
Snakes on slug patrol
Slug patrol is the primary duty of snakes at our place, slugs being a principal garden pest in the Pacific Northwest. Occasionally I’ll come upon a garter snake with a banana slug bulging from its mouth. I tiptoe away, gratified. The northern brown snake is reputed to be good for slug control, too. In the southern and central states, various species of green snake feed upon hornworms, crickets, and grasshoppers. The mole snake hunts mice and moles in their tunnels. The deep South and Southwest are richest in snake species, and while most of us would just as soon do without rattlesnakes, copperheads, and water moccasins, I wouldn’t mind having a few big rat snakes or corn snakes around to keep the rodents in check.
Shy and retiring creatures, most snakes don’t fare well where humans congregate. Dogs and cats are a menace to snakes, and so are numskull gardeners; I once heard one bragging about how he’d just sliced a garter snake in two with his spade. Lawn mowers are another menace, especially for grass-dwelling snakes like the garters.
Shelter is the prime requisite for a snake-friendly garden. Snakes need lots of crannies into which they can quickly retreat. Rock piles and dry stone walls with crevices are invaluable, as are undisturbed banks, ditches, and other wild areas. Our garter snakes overwinter in subterranean dens called hibernacula. Their favorite location is deep under big tree stumps, and a would-be wildlife gardener thinks very carefully before removing any large tree stump from the garden, so many are its advantages. Rock piles can also make good hibernacula.
Once active, snakes need to raise their body temperature by basking, for which they require safe and sunny exposed spots with shelter close by. Large flat rocks with southern exposure are ideal.
Toads are cutworm eaters
Garters and other snakes prey on toads and frogs, which is problematic because toads especially are breathtakingly good pest predators. In one night, a toad may gobble up as many as 100 army worms or cutworms, snails or slugs, tent caterpillars or sow bugs. “All 18 species of toads found in the United States have feeding habits that are of value to the gardener or agriculturist,” writes John V. Dennis in The Wildlife Gardener. To my mind, anything that eats sow bugs should be loved without restraint, but, unhappily, we have no native toad on the little island where I live.
Like the snake, the toad needs shelter if it is to survive, for it’s hunted by skunks, snakes, and predatory birds. Dogs and cats are less of a problem, as they quickly learn to leave a toad alone after a taste of it. Daytime shelter is essential, and toads will squat in a cool spot under old boards or rocks. You can make a classier toad hole using a concrete drain pipe set at an angle into a rockery or beneath a dry stone wall leading into an underground cavity with soft sand at the bottom. A toad hole must be situated so the toad can emerge into a sheltered area. As with snakes, swaths of uncut grass or other undisturbed patches are required.
Water is the other toad requisite, because the creature drinks by sitting in water and absorbing moisture through its skin. An amphibian pool is easy to install, and my experience has been that as soon as you introduce a water feature into your yard wonderful things begin to happen. The pool should be located in a secluded site in semi-shade and within easy reach of a hose so the water level can be kept constant. Something about 4 feet long, 3 feet wide, and 8 inches deep is appropriate, with one side sloping gently to the edge. (Swimming pools and sunken bath tubs can be deadly, because toads cannot climb out their vertical sides.) A pool can be lined with either cement or a heavy pool liner. Concrete needs to be cured for several months before it is safe for amphibians. A few inches of soil are spread on the bottom, then covered with fine gravel. Several larger rocks and a small log or two help, as does some aquatic vegetation, along with grasses or other cover-providing plants around the edges. Fishing herons and raccoons can be kept out with a poultry wire screen stretched over the pool and fastened to a wooden frame. In the best of all possible worlds, toads will breed in the pool, and as a single female can lay many thousands of eggs, a healthy toad population should ensue.
Mulch as a home for hunting spiders
Unlike snakes and toads, spiders don’t need much encouragement to live in the garden—other than keeping the pesticide sprayer in the shed. And what marvelous garden creatures they are! I vividly remember the day one of our tree peonies bloomed for the first time, a single huge blossom of creamy white petals flushed with a hint of pink streaking. Looking into the heart of the enormous flower, I discovered a large spider living there; her bulging cream-colored abdomen bore a faint pink stripe down either side, a brilliant duplication of her flowery house. She had a well-stocked pantry of mummified bees, wasps, and flies tucked among the golden anthers. Later I wondered what would become of her when the petals of her gorgeous dwelling fell away; then somebody told me this species of spider takes up summer residence in the Shasta daisies.
I suspect it was a crab spider, noted for its ability to change its coloring to mimic the blossoms within which it lurks. A number of spiders have this chameleon quality for blending into different backgrounds. These are primarily hunting spiders, typified by muscular tarantulas and wolf spiders, that catch their prey by either stalking it or by lying in ambush and suddenly rushing out upon it. They comprise about 40 percent of all spider species, the web spinners about 60 percent.
I stumbled inadvertently upon one very good way to encourage hunting spiders in the vegetable garden through our use of a thick mulch of grass clippings. We grow all our vegetables in raised beds mulched with grass. The primary purpose of the mulch is weed suppression and soil moisture retention, but I began noticing in summertime that wherever the mulch lay thick, it was alive with small black hunting spiders, whereas any bare earth nearby would have none. The mulch, in fact, is recreating the hunting and hiding opportunities spiders would naturally find in a meadow.
The spiders that spin webs to trap their prey are equally adept at insect control. Their webs—space webs, sheet webs, orb webs, cobwebs, or funnel webs—form structures of great beauty that enhance the texture of a well-formed garden. And never more so than in autumn, when tiny beads of dew are strung along the silken strands, creating tapestries as gorgeous as anything the garden has to offer. Last spring, I came upon a little hummingbird nest balanced on the twig of a cedar tree with three tiny dark nestlings inside, each scarcely larger than a house fly. I was intrigued to discover that the nest was knitted together and lashed to its supporting twig with lengths of spider web. What more reason could there be for having multiple spinners of silk in the yard?
Bats with a high insect-eating metabolism
Another, less poetic, wildlife interaction we endured last spring was a house invasion by brown bats that had taken up residence in a seldom-used chimney. Come evening, they’d work their way down the chimney and through a tiny gap in the Franklin stove into our living room, then spend the better part of the evening swooping around inside the darkened house and declining to exit through the doors and windows we’d throw wide open for that purpose.
This is the sort of behavior that gives bats a bad name, conjuring fears of their getting snared in your hair, of rabid biting and vampire blood-sucking. And there’s no excuse for it at our place because we have plenty of wildlife trees—huge snags of old-growth Douglas fir in whose cavities bats are naturally at home. But for some reason, they prefer our house.
Bat houses are a good way to accommodate bats without having to share your living room with them. Long popular in Britain, bat houses have been gaining favor in North America lately. These are bottomless rectangular boxes with dividers made of untreated, rough-sided wood spaced 1-1⁄4 to 2-1⁄2 inches apart to accommodate bats of varying sizes. A bat house is ideally located 12 to 15 feet above ground, out of the reach of predators, facing southeast, and close to a permanent source of fresh water.
Some people like to encourage hunting bats by leaving a light on at night to which flying insects are attracted. Again, the light should be 12 to 15 feet above ground so that cats or raccoons can’t use it as a place to catch bats. therwise, bat populations can be encouraged through citizen action to preserve ponds and marshes critical for foraging, trees and snags for roosting, and caves and old mines for hibernating. As for the rabies scare, scientists estimate that only 0.5 percent of bats carry rabies. Statistically, you’re far more likely to be maimed by a lawn mower than bitten by a rabid bat.
By bringing in bats, toads, spiders, and snakes, we as gardeners are well on our way to solving some of our worst pest problems, at the same time immeasurably enriching the garden ecoscape, and adding an element of beauty and magic that makes the garden a more richly textured and intriguing place to be.
posted in: cutworms, slulgs