Live and let live

Ah, winter again. 

Not long until the winter solstice

Footprints in this weekend’s snow reveal that even in winter there’s a lot going on in my yard that I don’t see. 

Squirrel prints, or something bigger?

I thought of this when I read Steve Aitken’s description of a painful experience in this month’s Fine Gardening (“I believe in a critter-proof garden.”) His first foray into growing lilies from bulbs ended when his flower buds became a meal for foraging deer: “. . . all that greeted me were some newly topless stems. And hoof prints.”

     I’ve had my unhappy wildlife interactions too, but not with anything bigger than a raccoon. Reading the FG piece, I realized that my experience with wildlife in the garden is pretty sheltered. If I lived a few miles west in Boston’s more woodsy exurbs, I’d be cursing at deer too. I might have bears eating birdseed from my feeders and coyotes howling in my backyard.

Luckily my lilies are safe from deer

    Back here in the first ring of suburbs, our yard hosts mobs of sparrows, sometimes flocks of starlings, and a coterie of small native birds that frequent the feeders. Turkeys rarely penetrate the fenced yard, and we’ve never seen a coyote on our third-of-an-acre property. 

     Nights bustle with mammal activity as opossums, skunks, voles and raccoons lead their lives nearby but mostly unobserved.  In daylight, rabbits have become an everyday sight in my yard in the warm months, and I occasionally glimpse chipmunks. Squirrels are so common that we ignore their acrobatic prowess.

If squirrels were rare, their abilities would amaze us

    In the city center rats, pigeons, squirrels, and European sparrows live as “human commensals,” species that benefit from a relationship with humans without affecting us directly. In my suburban town, a lot of animals have adapted to living near humans, but I wouldn’t say that they benefit. They’ve adjusted to our taking over their space, but they often pay a high price for proximity.

    For example, a recent sunrise revealed a dead opossum in the middle of a busy nearby street. Possums seem to be particularly ill-equipped for dodging cars, and in fact much of their mortality is caused by human activity. This one probably was trying to get ready for winter and thought she could cross that open space under cover of darkness (Here’s a link to some fascinating opossum information).

Opossum mother and babies

     
     So far I’ve had the luxury of enjoying animal sightings, after adjusting my gardening expectations. I learned long ago not to try to grow sweet corn, because raccoons were much better than me at sensing when the ears ripened. If I plant tulips, I know there’s a good chance squirrels will bite off the flowers as they open. I accept that I won’t harvest blueberries from my bushes, because birds will get there first. 

    But I’m not primarily a food gardener, and I can live without flowers that are too delicious for wildlife to pass up. Gardeners farther from the city may be trying to scare animals away or fence them out. Here in the suburbs, I try to offer a garden where we can all get along.

Dear readers, I'm going to take a break next week. Best wishes for happy and peaceful holidays. See you in 2017. 

Trees or solar panels?

For years I’ve wanted to install solar panels on our roof. My sister Kate is an environmental activist who was an early adopter of solar power here in New England. 

Kate and her solar array

 Since installing her solar panels in 1998, she has generated her own electric power, selling power back to the grid when she generates more than she uses.

    To enable this, she first made her house as energy efficient as possible. That’s the cheapest way to reduce your use and cost of electricity, Kate points out.

    More recently, my brother- and sister-in-law, who live in sunny Los Angeles, have been able to use their solar power to charge Bob’s plug-in gas-electric hybrid car, so a significant part of his driving is carbon neutral. 

Wouldn't it be great to power your car with solar-generated electricity?

    I would love to generate electric power at home like these inspiring family members and dispense with power from coal, gas and nuclear sources. The problem is that we live in an older suburb, so we’re surrounded by mature trees. That’s a good thing. After all, one of the basic recommendations for addressing climate change is to plant trees, because they sequester carbon. 
    
     They also shade the house, screen it from the wind, and even lower the ambient temperature in summer. These “ecological services” decrease our energy use for cooling and heating.

Street trees convey many environmental benefits

    I called a solar installer to ask if our roof would qualify for solar panels. Looking at satellite pictures of our lot, he said we’d have to ask the city to cut down our street trees to let sunlight fall on the roof. But our town has lost so many street trees over the years, there’s an active volunteer organization working hard to replant. I didn’t want to eliminate healthy street trees, even though they are Norway maples.

    I asked Kate for advice. She didn’t favor cutting down the trees either, to my relief. She pointed out that I can achieve my sustainability goal a different way. We can choose to get our electric power from renewable sources.

    So far I’ve found two suppliers that both look reasonable. CleanChoice Energy uses power from wind and solar farms from New York to Maryland. Mass Energy Consumers Alliance offers two plans, one strictly Massachusetts wind power, the other a mix of sources including twenty-five percent in-state wind,

solar, and anaerobic digester gas power and seventy-five percent “low-impact” hydroelectric power. 

We could opt for wind power

     Of course the electric power coming into our house won’t magically change to pure golden renewable energy. If we opt for the renewable sources, the energy we draw from the grid will be matched with energy from renewables. That will increase demand for renewable energy and, over time, help bring the price down. Right now we’ll have to pay an extra (tax-deductible) $20 per month for peace of mind. 

    In the current political climate, with the EPA on the chopping block, it’s a cost I’m willing to pay. That way we can still live surrounded by trees.

Fighting caterpillars from within

Winter moths are appearing on the storm doors again,

so I was eager to attend a recent talk by Professor Joe Elkinton. Elkinton is an entomologist at UMass who not only studies infestations of nonnative insects, he actually does something about them. His speech about gypsy moths and winter moths alerted me to a gardening quandary I’ll need to resolve.

Birch leaves chewed by winter moth caterpillars

    Gypsy moths (Lymantria dispar) came to Boston in 1868, imported by Étienne Léopold Trouvelot, an astronomer in Medford, Massachusetts who was trying to mate them with silk worms. In an all-too-common scenario, they escaped from his custody and traveled across Massachusetts defoliating trees over vast areas. The last major outbreak was in 1981.

Life stages of the gypsy moth

     In an interesting ecological twist, gypsy moth populations were decimated soon afterward by a newly introduced fungus. This year’s drought changed the balance by limiting the fungus, so gypsy moths surged. 

    Elkinton said that biological control—introduction of organisms to kill unwanted insects such as gypsy moth—was tried as far back as 1905. In this approach, insects that control the pests in their homeland are brought over to do the same here. 

     Early on, one introduced parasitoid killed native insects, such as the beautiful luna moth (Actias luna).

The luna moth is a North American native

A parasitoid, unlike a parasite, ultimately sterilizes or kills its host. 

    That brought me to what I wanted to know from Elkinton’s talk. How can we be sure we won’t cause more problems by releasing new nonnative insects to control the ones we don’t like? His answer was, “Host range testing.” This means carefully evaluating the insect you’re planning to release, checking whether it will use native insects as hosts. Entomologists in this field only release parasitoids or predators that specialize in one nonnative insect, unlike goofballs like Trouvelot. 

    Winter moth (Operophtera brumata), also from Europe, got to the US in 1950 and has been a major problem in eastern Massachusetts since around 2001. The larvae, little caterpillars, tunnel into buds and eat young leaves of most of our deciduous trees. Elkinton has been releasing a tiny tachinid fly, Cyzenis albicans, to parasitize winter moth larvae. 

Winter moth caterpillar

     This is a long process. It takes three to five years after introduction to establish a population of the fly in a new location. To determine whether their efforts are succeeding, his team and volunteers harvest 120,000 caterpillars in May and check whether each contains flies.

    Elkinton revealed that my neighborhood has an established population of C. albicans. He predicted there will be enough of them next summer to make a significant dent in the winter moth population.

    Thereby hangs a sustainability dilemma. If I continue having my trees sprayed to kill winter moth caterpillars, I’ll kill the little flies inside the larvae as well. I’d like to let the flies do their job, but if they don’t, the caterpillars will defoliate the trees. I think I'll take a chance and skip the spraying.

Last foliage of the year. This ornamental plum could be defoliated by winter moth next summer if I guess wrong.