Critters in the Garden
by Stephen Church
“What are you doing?” a neighbor asks as she pauses on her walk.
“Making a toad house,” I reply.
“Oh, no!” She recoils, wide eyed, saying “I have a phobia about toads.” She hurries away, and I return to the task.
Any mention of toads, snakes, bats, spiders and other generally less-than-popular critters often elicits a reaction similar to that of my neighbor’s. So why would we want these organisms in our yard? First, their presence is a sign of a healthy ecosystem. If they are able to survive and thrive in our yards, we are doing something right. Second, they are helpful. These animals control pests for free and in an ecologically responsible fashion. That means less work for us, and fewer chemicals. Third, they are fascinating to watch.
Habitat gardening is increasingly important in our world. As gardeners, we can provide the necessities for many organisms with a little thought and effort. As gardeners, we can help foster an appreciation for these creatures and the vital roles they play in nature and in our yards.
AMPHIBIANS — Toads and Frogs
So, what good are toads in the garden? It turns out they play an important role in pest control. According to Penn State, a toad’s diet consists mostly of garden pests — in fact,”88% of their prey are invertebrates that are classified as agricultural pests. In a three month season, a single toad will consume just under 10,000 insects and, thus, has a significant economic value for farmers and gardeners.”
Of the nearly 100 species of toads in the United States, many live in the southeastern states, where they eat flies, crickets, locusts, grasshoppers, bees, wasps, beetles, spiders, caterpillars, earthworms, slugs, and snails. They also eat mosquitoes, pill bugs, and cutworms, and, along with frogs, they are “essentially the only beneficial creature that will eat cucumber beetles.” (other predators shy away from cucumber beetles because they become bitter-tasting after they’ve dined on cucumber and squash vines). Toads are “sit and wait” predators, doing just that to capture their prey with their lightning fast tongues.
Toads generally find shelter in the heat of the day by hiding under leaves, brush, logs, or in burrows. We can encourage toads in the landscape by providing shelter and water for them. Toad houses — also known as toad shelters — are easy to make. One easy approach is to carefully break out a portion from the rim of a clay pot to use as an entrance. Invert the pot and press the rim into the ground. Another approach is to break a clay pot in half (from top to bottom) and press the broken edges into the soil, forming a toad “Quonset hut.” Place the toad shelter in a shady area with water nearby. Use a small bird bath dish or just a clay pot saucer as a water source.
Frogs are similar in value to toads. Tadpoles of both species eat mosquito larvae, and adult frogs can help control adult mosquitoes. Although bullfrogs can be noisy, they do eat small rodents.
Frogs require more water than toads but are easy to attract. If you have or build a pond, they’ll come. Providing for these animals is increasingly important, as amphibians are under tremendous stress for a variety of reasons, not all fully understood. Frogs and toads are very sensitive to chemicals. Avoiding their use encourages them to hang around.
Despite the myth, toads have “warts” but don’t cause them. Toads do have glands behind their eyes that secrete substances that are unpleasant and toxic to predators, but not to humans. Pets can become ill if they eat a toad. If you handle a toad, wash your hands afterwards and avoid touching your eyes or nose.
Snakes. Just the word makes some people’s skin crawl. Any list of most feared or hated animals features snakes. Many people have a visceral fear of these animals, but, as gardeners, we should be in the forefront of their defense. As a reminder, it is illegal to kill a snake in Virginia and many states, unless it’s a threat to health or property.
• How many snakes are native to Virginia? There are thirty-four species of snakes in Virginia, only three of which are poisonous. The cottonmouth, or water moccasin, lives only in Southeast Virginia. The rattlesnake lives in western Virginia and some have been seen on the Blue Ridge in Nelson County. The copperhead, which is found in central Virginia, is the least venomous of Virginia’s snakes. It is a pinkish to tan snake with brown hourglass bands on the back and a white belly with black spots.
• How do I know if it is a poisonous snake? Look at their eyes and their heads. Non-venomous snakes have round pupils. Poisonous snakes have vertical ones. Poisonous snakes have a small hole between the eye and the nostril on each side of the head, thus the name pit viper. The heads of Virginia’s venomous snakes are wider than their necks, but this broad head is also a characteristic of some nonvenomous snakes and is not a reliable yardstick. Another difference, of somewhat dubious value, is that venomous snakes have a single row of scales on the underside of the tail, while nonvenomous snakes have a double row. All of Virginia’s venomous snakes bear their young live. Snake eggs come from non-venomous snakes and do not pose a danger.
• So what good are snakes? First of all they don’t eat plants and what they do eat, often does: moles, voles, mice, slugs, grasshoppers, and other invertebrates that can plague our gardens. Beyond the damage to plants that these animals do, some often carry ticks. The white footed mouse is a major carrier of the blacklegged tick (also known as the deer tick), a primary vector of Lyme disease. The white footed mouse is also a carrier of the Hantavirus, a scary respiratory disease found mostly in high-altitude states in the West. www.psu.edu/dept/nkbiology.
What are some snakes commonly found in this area? The brown snake is a 15-inch long snake whose diet includes slugs. Two snakes are often referred to as “black snakes.” The black rat snake is jet-black and shiny, while the black racer is grayish black and less shiny. But both eat insects and rodents. The king snake has black coloring as well. It eats mice, lizards, and other snakes, including venomous ones. These reptiles also eat some desirable animals, like birds and toads, but there is a cost to all things.
Turtles are a sign of a healthy ecosystem. Turtles that live in Central Virginia include the snapping turtle, the Eastern painted turtle, the spotted turtle, the Eastern mud turtle, the Eastern river cooter, and the woodland box turtle. This last turtle — the woodland box turtle — is the one with which you are probably most familiar. It eats slugs among other things. It has a life cycle and span similar to humans, reproducing at about 20 years of age and living 50 plus years, unless it tries to cross a busy road. Turtles are among the species with the largest conservation needs due to loss of habitat among other things.
Virginia’s lizards are primarily skinks of various types. Most are small, under eight inches, although the broad-headed skink grows to a foot or more. They live under leaf debris or in cracks in concrete or masonry. The skink’s diet is a good one for the garden. They primarily eat small invertebrates, like grasshoppers, stinkbugs, millipedes, snails, and wood roaches.
Songbirds are well known for their prowess at catching insects in mid-air or on the ground, but they are not equipped to handle the larger prey of hawks and owls.
At least seven species of owls are native to Virginia, including saw-whet, barred, screech, barn, horned, long eared, and short eared owls. These predators are excellent at controlling rodents. They eat rats, mice, voles, rabbits, squirrels, and gophers among other prey. Of course, they also eat some other birds as well as other beneficial animals. Owls are attracted to sites that offer a good food supply and nesting sites. They will nest in old trees or nesting boxes. Nesting boxes may be purchased or built. Plans to build boxes are available on line at various sites, including: Kentucky Department of Fish and Wildlife and rain.org.
Hawks are another helpful avian predator. Central Virginia is home to the red-shouldered, the broad-winged, the red tailed, the sharp-shinned, and Cooper’s hawk. Most of these eat mice, voles, chipmunks, and other small mammals. They also eat some things we want around like frogs, snakes, and small birds, but the tradeoff is worth it, especially when we spot one circling in the air or perched in a tree in the yard, a majestic sight.
While not a predator, the vulture’s role as a scavenger is a beneficial one. Most mammals do not die as the result of predation. Cars, illness, love triangles, lack of food, and parasites are major causes of death. Vultures clean up nature’s messes. In doing this job, they help us. Dead animals can harbor diseases. Vultures’ stomachs are acidic and sterilize the remains. If they don’t eat these things, something else will, usually maggots or bacteria, an ugly and smelly process.
One unusual characteristic of turkey vultures is their sense of smell, something few birds have. They also have excellent eyesight. When they fly, their wings form a “V”, and they tip from side to side. This movement can give them a silvery appearance.
As anyone who has read Douglas Tallamy’s Bringing Nature Home can tell you, insect diversity is of fundamental importance to our gardens and to our world. Insects provide food for many of the animals mentioned in this article, and they are important predators in their own right. The vast majority of insects are either benign or beneficial. However, the few bad ones wreak havoc in our gardens and landscapes, giving a bad name to all insects. And we must remember that most insects are our allies, and that some function as both allies and adversaries, to borrow the terminology James Nardi uses in Life in the Soil, a book well-worth reading, by the way.
We know that assassin bugs, wasps, spiders, mantids, minute pirate bugs, lady bugs, centipedes and other predatory insects eat garden pests, but they also eat “good” insects. Caterpillars are “bad” — until they turn into pollinators. We cannot easily discriminate between the “good” and the “bad.” Nature is amoral.
Welcoming these insects involves a number of steps. Insects and pesticides are, largely, mutually exclusive. Many of these insects can tolerate the occasional use of a narrow spectrum pesticide, but many bees and butterflies are often very sensitive to even this practice. The predators discussed here can go a long way towards controlling these pests without chemicals.
What we plant is another key to attracting these predator allies. Large lawns don’t help, while shrubs and trees do. Food, water, and shelter, along with a diversity of plants, preferably at least some native, will help attract and retain these beneficial insects. These practices benefit most of the organisms identified in this article.
As humans encroach more and more on wilderness areas, habitats for many wild mammals are continuing to shrink. We have to learn to get along with wild animals in the back yard, including skunks, foxes, opossums, bats, etc.
Skunks? But they stink! They carry rabies! They tear up my lawn! Yes, but skunks can be highly beneficial to gardeners. They are omnivores, eating both plants and animals, but in the summer, they eat more animal matter. Their favorite foods include crickets, beetles, grasshoppers, and grubs. They also eat mice, mostly in the winter, and, when food is scarce, they will go after rats and rabbits. In the vegetable garden, they can be particularly useful as biological controls of white grubs. Just be on the lookout for odd behavior and other symptoms of rabies because skunks are common carriers.
With skunks and lawns, it’s pick your poison. Skunks eat grubs. In the lawn, this can be harmful because the skunks tear up sections of grass to get at the grubs, but these grubs will eventually damage that very area. Also, the adult forms of these larvae are often harmful to flower and vegetable gardens, including Japanese beetles which, as we all know, can wreak havoc. Other white grubs can be May beetles, June beetle, chafers, and other scarab beetles. You can read all about white grubs at “White Grubs in Vegetable Gardens,” Va.Tech Entomology/pubs.ext.vt.edu
Iconic Halloween animals, bats have long suffered a spooky reputation. They’ve been accused of harboring vampiric spirits, making nests in piles of ratty hair, and are often associated with witches, warlocks and Halloween. Few other mammals seem to spook us with so many misunderstandings. But bats, because of their incredible echolocation abilities, rarely fly into or touch people, and serve amazing and essential ecological roles in our gardens.
First, let’s examine some common bat myths. Yes, there are vampire bats—exactly three species out of more than 1,200 species of bats worldwide. And yes, they do drink blood, but they are far—far—more likely to get it from cattle or other mammals than from you. And rather than sinking long fangs into an unguarded neck, the vampire bat will usually slice a small section of skin away and lap up the blood, using an enzyme in their saliva to keep the blood from clotting, an enzyme, by the way, that is used to treat stroke victims. Currently, the range of vampires bats found in North America is limited to South America and Mexico, with one exception: one single specimen has been recorded in the United States. That single rare event occurred in the extreme southwest tip of Texas. So one can only conclude that the likelihood of being attacked by blood thirsty bat is highly unlikely.
Another myth is that bats will fly into your hair and become entangled. Possible, yes. Likely, no. Bats are highly evolved not to run into things, especially not some big, potentially dangerous, slow-moving mammal. Bats are not flying mice. Not even close, except that both are mammals.
A very common myth is that bats are deadly because they are all infected with rabies. In truth, less than one percent of bats are rabid. Let’s look at the numbers. There is an average of one death per year due to rabies transmitted by bats. Compare that to deaths from other causes. About 50 people die each year from lightning; bees kill more than 50 people annually; and dogs kill about 30. It is true that bats are four times more likely to kill people than elephants, which kill 0.25 people annually in the U.S. on average. A bat would only fly into your hair if its prey did, a good argument against beehive hairdos, if one were really needed. In addition, bats are afraid of humans and avoid contact. Bats are not dirty; they groom themselves like cats do. And yes, bat droppings (also bird droppings) can carry histoplasmosis, a fungal disease that primarily affects people with weak immune systems, but this is uncommon. Transmission of the disease is most common when the spores are disturbed, usually by construction or demolition projects.
All bats in this part of the United States are insectivores, which says it all about why they are beneficial to the gardener and those of us who enjoy sitting outside in the evening. A bat eats insects as it flies, using echolocation, reflected sounds that locate prey or obstacles. It may catch the insects in its open mouth or in its wings or tail. As it approaches the insects, it rears up slightly, spreading is wings and curling its tail into a barrier that catches the prey, which it eats on the fly.
There are 16 species of bats in Virginia, with the Virginia big-eared bat (Corynorhinus townsendii virginianus) being the state bat, despite the fact that it’s rare, found only in a handful of western counties. Species commonly found in this area include: Eastern red bat (Lasiurus borealis), Eastern Pipistrelle (Pipistrellus subflavus), hoary bat (Lasiurus cinereus), Northern Myotis bat (Myotis setentrionalis), little brown bat (Myotis lucifugus), big brown bat (Eptesicus fuscus) , and the silver-haired bat (Lasionycteris noctivagans). Of these species, two — the little brown bat and the big brown bat — are the ones most likely to take up residence in a building.
Bats are the only major predator of night-flying insects; one big brown bat can consume between 3,000 and 7,000 mosquitos in a single evening, while a little brown bat eats up to 600 mosquitos per hour. Bats also eat large numbers of harmful forest and agricultural pests, including moths, beetles, flies, and leaf hoppers.
To attract bats, we can do a couple of things. One is to build or buy bat houses. Another is to let dead trees stand if possible. Bats need a source of water nearby as well. The Community Bat Programs of BC and National Wildlife Federation both offer free online bat house plans.
Foxes are another predator with an undeserved bad reputation. A healthy fox poses little to no threat to people, although cats may want to steer clear of them. Foxes are crepuscular, active mostly at dawn and twilight, but in suburban and urban environments they are more prone to be out and about at other times because a food source may be nearby. Just because you see a fox, it does not mean it is sick. If it is bold and approaches you, it may be sick. Unnatural movement or confusion are other signs of illness.
So what good are foxes for our purposes? Much of their diet makes them an ally. They feed mostly on rabbits, mice, bird eggs, insects, native fruits and, sometimes carrion. And again, healthy ecosystems require predators of all sizes.
Last come the opossums. The only native American marsupial, it would win no beauty contests, but its usefulness outweighs its ugliness. So what do they do for us? They are immune to many toxins in nature. Scientists hope to find what substance in their blood causes this immunity. This trait allows them to eat rattlesnakes, which we may see as a plus. Other parts of their diet are beneficial to gardeners for the most part. They eat virtually anything, including fruits and vegetables in our gardens, but they tend to like the decaying things, thus helping us keep our gardens clean. The rest of their diet includes garden slugs, insect pests, rodents, toads, snakes and even dead animals. Best of all, opossums kill ticks by the thousands. Researchers have found that one opossum can kill up to 4,000 ticks in a week. Opossums rarely carry Lyme disease and are very clean. During their grooming, they kill and/or eat many ticks. This is good news with the increasing worries surrounding tick-borne disease. And if you really can’t stand them, be patient. They are transient animals, staying in a place only a few days and then moving on, although a female with pups may hang around longer.
Diversity is a hallmark of a balanced ecosystem. As gardeners, we seek to understand and use the interrelationship of plants, animals, and abiotic factors. These “critters” are a sign of ecological health in our yards. They help keep that balance. They may not be attractive to look at, and they may not be without flaws, but they are valuable to us and to the environment and, as such, deserve our help and respect.
Bringing Nature Home: How You Can Sustain Wildlife with Native Plants, (Tallamy, Douglas W., 2007 and 2009)
Life in the Soil: A Guide for Naturalists and Gardeners (Nardi, 2007)
“American Toad,” The Virtual Nature Trail at Penn State New Kensington, http://www.psu.edu/dept/nkbiology/naturetrail/speciespages/americantoad.htm
“Snakes,” Virginia Herpetological Society, www.virginiaherpetologicalsociety
“Foxes,” University of Maryland Extension, https://extension.umd.edu/hgic/foxes
“Bats of Virginia,” Virginia Places, http://www.virginiaplaces.org/natural/bat.html
“Bats,” U.S. Fish & Wildlife Services, .fws.gofws.gov/refuge/hanford_reach/wildlife_habitat
“Bats,” Working with Wildlife, North Carolina Extension Service, https://content.ces.ncsu.edu/bats
“Do Vampire Bats Really Exist?” U.S. Geological Survey, https://www.usgs.gov/faqs/do-vampire-bats-really-exist?qt-news_science_products=7#qt-news_science_products
Center for Disease Control, Wonder Database, https://wonder.cdc.gov
“Rabies Information: Facts and Fallacies,” BatWorld Sanctuary, https://batworld.org/rabies-info/
“Opossums: Unsung Heroes in the Fight Against Ticks and Lyme Disease,” http://blog.nwf.org/2017
“Living with Wildlife in Illinois,” web.extension.illinois.edu/wildlife
“Skunks,” U.Md.Ext., extension.umd.edu/hgic/skunks-lawns
“Wildlife in the Home Pond Garden,” Va. Coop. Ext. Pub.No. 426-045
Raptor Conservancy of Virginia Website, raptorsva.org
“White Grubs in Vegetable Gardens,” Va.Coop.Ext. Pub.No. 3104-1570, Va.Tech Entymology/pubs.ext.vt.edu