Garden Notes

Roaring Brook with ice formations
The groundhog wants to know: are they freezing or thawing? Roaring Brook with ice formations. Photos by Susan Safford

Winter's prognosticator

By Abigail Higgins - February 1, 2007

Weather justice was recently meted out to all who complained about the absence of real winter. I still hope Groundhog Day brings a wintry, fully moonlit sky, beneath which lies a beautiful snow cover on the ground below. It may have been shortened, but it is all the winter we've got, it is here, and there is some cold. A covering of snow would make these poor misled plants, awakened and stirring in their beds, a little safer and more comfortable.

What would the groundhog say about climate change?

If Candlemas be fair and bright,
Winter has another flight.
If Candlemas brings clouds and rain,
Winter will not come again.

Photo

In contemporary American life we speak of Groundhog Day, a popular ritual and cause for jocularity among morning television personalities and meteorologists. Obscured within it are the Christian Candlemas and pre-Christian Imbolc rituals of other eras, and an age-old desire to know what the future (the weather, put another way) holds.

According to Wikipedia, "Imbolc is traditionally a time of weather prognostication, and the old tradition of watching to see if serpents or badgers came from their winter dens is perhaps a precursor to Groundhog Day." Water was thought to thaw and begin to flow at Imbolc. The name reflects its origins in the word "i mbolg," meaning in the belly, and refers to the pregnancy of ewes, a sign of spring. It was a festival of fire and poetry, sacred to Brid, the Irish deity of streams and wells.

Today the Internet is a bit like the groundhog's personal assistant, a never-ending source of weather information. Long-range forecasts for northeastern North America, based in part on the appearance of a Pacific Ocean weather syndrome known as El Nino, call for a warmer than usual winter and generally heavier than normal rainfall. El Ninos have been associated with reduced hurricane activity in the past.

However, one problem facing climatologists is the uselessness of their climate models. As the base data become rapidly obsolete and real-time conditions are heating up, the computer models lose their predictive value. For instance, the web site of the National Arbor Day Foundation (www.arborday.org) has posted interesting maps showing the extent of change in our North American plant hardiness zones between 1990 and 2006. Back in 1990 we were zone 6; today we are zone 7, a whole zone warmer. It may be that hurricane activity is influenced by factors other than, or in addition to, El Nino.

More on caterpillar nation

There is a great deal of consternation and buzz on the street about winter moths (Operophtera brumata). How bad it is going to be, come spring? If the predictions associated with El Nino are accurate, we can hope that abundant rainfall offsets the caterpillar damage, by bolstering tree recovery and the ability to releaf. What much talk ignores is that we have unusual numbers of three - not one - "inchworm" caterpillars and their moths. The fall cankerworm (Alsophila pometeria) and the spring cankerworm (Paleacrita vernata) are very much players in the ravaging of Island woodlands.

The on-going mild conditions have caused continued sightings of numerous moths around outdoor lighting. All the male moths I have examined - and there have been at times drifts of them - have been fall cankerworm moths. I have been looking at tree trunks and bark, exterior walls of houses, in an effort to find eggs of winter moth. I can find hardly any. The fall cankerworm egg masses, however, are everywhere. I would highly recommend the excellent pages that the University of Massachusetts team - Bob Childs, Deborah Swanson, and Dr. Joseph Elkinton - have posted on the internet to educate us about the differences in these inchworm caterpillars: www.umassgreeninfo.org/fact_sheets/defoliators/wm_id_man.html and the treatments available to control them.

The appearance of the fall cankerworm egg mass is of a neatly arranged array of steely grey dots, tightly packed in neat alternating rows, to be found on shingled walls, twigs, tree trunks, porch posts, and so on. The adult male moths (the females are wingless) are very similar to winter moths; however, the male fall cankerworm moth has a light colored spot that is an identifying mark on the outer edge of each forewing. A photo illustrating a recent article about the moths in this paper (Winter moths ascend on Vineyard once again, Dec.14, 2006) was actually a fall cankerworm moth, showing the light spots very clearly. They are quite apparent when the moth is at rest. The winter moth has a faint scalloped band of darker markings, "hash marks," across the edge of the forewing but no light dot.

Meanwhile, the spring cankerworm moths are getting off lightly in all the fuss. I suspect that some of the moths we are seeing, attracted by outdoor lighting, are probably spring cankerworm moths. This non-descript small moth is also a dingy off-white, the females wingless, the larvae a greenish inchworm with lighter stripes on its side, and the eggs similar in color and arrangement, to the fall cankerworm. But the spring cankerworm does its mating starting in January and continuing through March, and with all the phenological confusion due to climate change, in all likelihood the moth mix we are seeing contains spring cankerworm moths.

I would like to remind everyone (but in a nice way) to go easy on salting sidewalks, steps, etc. if we get more wintry conditions. Yes, no one wants a nasty fall. However, sand, sawdust, and fireplace ashes also serve as able anti-slip substitutes (or fillers to extend salt) without the harm to vegetation, pet animals' paws, life in the soil, and pollution of drinking water caused by over-salting.