Last year, almost 250,000 acres of land in Massachusetts were defoliated by gypsy moths working in concert with forest tent caterpillars. Winter moth caterpillars gobbled another 21,000 acres. These depressing figures come from the University of Massachusetts's web site, umassgreeninfo.org. Ed Pierce, the Century21 real estate broker whose office is next door, e-mailed a link to the UMass web site by way of alerting all of us that last year's mess is likely to be duplicated in a few months. And the 2007 edition of monster moth madness may even be worse.
Naturally, our scrub oak dominated, residential wilderness contributed to this appalling total. And the news could be worse, because UMass reports in its Hot Facts Sheets that "recent winter moth pheromone trapping has indicated that the actual number is probably much higher than reported. In many areas, gypsy moth, winter moth and forest tent caterpillars were all feeding on the same plants in mixed populations, thus making it very difficult to sort out which one was the primary feeder."
Actually, I suspected as much, because the destruction was so complete and the pests so varied. I didn't need an NSA team to mine its intercepts to figure out that the enemies had made a mutual assured destruction pact to make all the trees and bushes at our place bare naked. They nearly succeeded too, and it looks as if the new crop of moths will be on the job in astounding numbers.
"Researchers from the University of Massachusetts and the MA Department of Conservation and Recreation are now in their second year of studying this pest in the Northeast, establishing its range, and actively working to implement a successful means of biological control (i.e. Cyzenis albicans). Trunk banding to measure the population sizes of adult winter moth in the highest density areas has now been performed for two years," according to entomologist Robert D. Childs and Deborah C. Swanson of the UMass Extension.
"The findings have been sobering," Childs writes. "It is roughly estimated that there were between 1,000 - 2,000 female moths per tree in those research areas, and each female produces about 150 eggs on average which translates into a minimum of 150,000 eggs per tree. Now, due to the pheromone trapping and DNA analysis of the captured males, it is apparent that winter moth is now well beyond the initial area of outbreak (Plymouth County, MA)." It may be that the infestation in Plymouth County, just north of us across the Cape Cod Canal, was worse than the carnage we experienced, but here, it was discouragingly extensive and ugly. If your homestead was the focus of a moth-caterpillar eat-in, the after-action moonscape was certainly enough to break your heart.
What to do? The UMass experts discuss a variety of control techniques, several of which seem promising, both because they are environmentally benign and because they present low risks to humans. But, little research is available to support a conclusion as to their effectiveness. On the other hand, spinosad, a "biorational compound that works well against winter moth and most other caterpillars," is extremely helpful, based on our experience. Conserve SC is the big-time name among spinosads, for use by licensed applicators only. The spinosads for the unlicensed are Bulls Eye Bio-Insecticide or Monterey Garden Insect Spray. UMass reviews spinosad as "fairly gentle to other organisms, such as the parasites and predators that we want to encourage." It's toxic to bees, so it needs to be used after the moths appear but before flowering trees are in bloom. Timing - for defeating the winter moth populations and protecting the bees and the apple trees - is everything.
Between now and January, adult winter moths rise from the soil like zombies and, energized by the Christmas lights, flutter busily about their romantic affairs. The female moth doesn't fly, but she "emits a sex pheromone that often attracts clouds of male moths." Wouldn't you know it? That pheromone stuff is everywhere.
They mate, she lays eggs, the adults die, the eggs await spring. Things get going again in late March, early April, when the average temp gets up into the 50s and the eggs hatch and set out to get a meal.
So, while we're Christmas-ing and planning a week's skiing or a February trip to Florida, the foundations of this year's onslaught are being put in place all around us. While we have forgotten the bare trees, the hideous debris, and the shade-less summer, our insect adversaries are doing their thing. Their timetable is set. For us, it's the moment for watchful planning.