It has been a spring season scented with lily of the valley, lilacs, and freshly mowed grass, while being colorized by red tulips, brilliant yellow daffodils, and deep purple columbine. It is the spring we dreamed of in January and February as our gardening hearts were in the deep freeze. You’d think that nothing could tarnish this verdant phase, not a single thing. Alas, that is not the case – munch, munch, slither, slither.
By the time you read this, the obvious parts of the invasion may be nearly over, the damage done, losses counted in the thousands of dollars. I’m talking about winter moth caterpillars. I’m talking about the millions of worms covering homes, hanging on invisible webs from nearly every leaf and tree limb. I’m talking about an invasion of catastrophic proportions.
For the past several years, southeastern Massachusetts has been infested with the Canadian winter moth. Not unlike Canadian geese, once just a migratory visitor, this Canadian import is also here to stay.
My own unhappy experience with this season’s onslaught of worms was preceded by an earlier event.
About six years ago, this area sustained a cyclical invasion of gypsy moths. Thick, hairy, undulating blankets of caterpillars covered every surface outside our home, including the exterior of the house.
Nothing brought me greater pleasure than returning home after a day in corporate hell, oops, I mean, a day at the office and enjoying our lovely property. One evening upon returning home and entering the backyard, I was completely enveloped in webs. It was like walking into a thick atmosphere of invisible threads that covered me from head to toe. Once my eyes adjusted and I could see beyond my nose, I found the backyard had become a science fiction movie. Every limb of the massive oak trees that were a feature of the backyard bore thousands of caterpillars parachuting in on silk. It was apocalyptic in scope.
Though we tried to persevere over the coming days, fighting the caterpillars with every known treatment along with a few we invented, nothing stopped the invasion. The gypsy moth caterpillars were winning. That was when I lost my mind.
I insisted the trees be cut down. Five humungous oak trees that had provided shade for decades were surgically removed from the property. I am not proud – I feel regret and guilt. But what is done is done. We marveled at how wonderful the sunlight was as it shone down upon us.
Then came the Canadian winter moths. Guess what they love to eat – maple trees.
In our front yard we have four very large maple trees. The main entrance to our home is situated directly under a glorious Japanese red maple, now a drive-thru fast food venue for the winter moth caterpillars. These invaders eat, hence defecate, all over the front steps. The tops of our brand new trash and recycle containers are literally peppered black with caterpillar fecal matter. Nature will have its way.
Web-based research has turned up little in the way of hope, but here’s what I found.
Scientists at the University of Massachusetts Amherst, led by Entomologist Joseph Elkinton, released about 2,000 parasitic flies at the Trustees of Reservations’ Rocky Narrows Reservation in Sherborn, Mass back in May 2014 to control winter moth caterpillars. This particular fly succeeded in controlling the moths in Nova Scotia and the Pacific Northwest, according to the UMASS website.
The flies lay their eggs right on the leaves so when the caterpillars eat them, they hatch inside the caterpillar and develop into a larval fly. In May, the winter moth caterpillars form pupae in the soil. The pupae containing the larval flies inside will soon die and the adult fly emerges the next spring to continue the cycle, attacking the caterpillars.
According to Elkinton, the fly will eventually subdue winter month population to less harmful levels.
“That is what happened in Nova Scotia, where the fly was introduced in the 1950s, and where winter moths have been at low levels ever since,” states Elkinton on the website.
I learned that the caterpillars feed on the leaf buds as well as leaves, but if conditions are right, and the tree has not been too heavily stressed from previously attacks or other problems, they will produce a second budding and leafing. The tree will most likely survive. But the year upon year eating away at the trees coupled with drought will have a long-term negative impact on our trees. Tree City USA, how I loved thee!
Some locations in town may not notice the caterpillars, while other neighborhoods will be grotesquely shredded one leave at a time. One thing remains a harsh reality – these pests have established themselves and have no natural local enemy to keep them in check.
After feeding on the leaves, the caterpillars come down to the ground where they pupate in the soil for the summer. Around Thanksgiving, as the days grow shorter and you turn on the outside lights to illuminate the path to your welcoming bountiful hearth, family and friends will have to fight their way through the flutter of thousands of tiny white moths – our Canadian visitors are here to stay – eh.
I couldn’t find any information confirming that the parasitic flies will in fact be released in Mattapoisett, but if anyone with authority over cyzenis albicans (aka: moth killers) is reading this, please use my property as a base camp for any moth eradication study. My grandparents may have emigrated from Canada; however, as far as I’m concerned, the bugs need their visas revoked.
By Marilou Newell
