Trees, moose may regret winter's warmth
New Hampshire's warmish winter could mean there are more tree-eating and moose-killing bugs on the prowl this spring.
'It looks like a bad year for the hemlock woolly adelgid,' said professor Alan Eaton, entomology specialist at the University of New Hampshire Cooperative Extension. 'I wouldn't be surprised if we saw an increase this year.'
The mild winter will also increase the winter tick population, Eaton believes.
'I hope I'm wrong, but I'm afraid I'm right on this,' he said. 'We're bracing for some problems with ticks.''
Mary Stampone is a climatologist with the New Hampshire State Climate Office. Compared with the average temperatures from 1981 to 2010, she said, this year has been warmer. Average annual snowfall ranges from 60 inches to more than 100 inches across the state. January temperatures range from an average high of 34 degrees on the coast to overnight lows below zero in the far north and at high elevations.
According to data provided by Stampone's office, the average temperature this past January was 23.4 degrees, 5.3 degrees warmer than the 1901-2000 average, placing it as the 15th-warmest January in 118 years. Just 2.98 inches of precipitation fell in January, 0.22 inches less than the 1901-2000 average.
'The warmer temperatures we had back in December extended the season for winter ticks,'' said Eaton. 'The leaves stayed on longer, which they use to cling to until they attach to passing animals, like moose.
'The moose can only withstand so much blood loss, and if they have over a hundred of these ticks on them, they can die. Unfortunately, I think we'll start seeing a rise in moose deaths in late March or April.'
The hemlock woolly adelgid (HWA), native to Japan and China, feeds on ornamental hemlocks as well as native trees. Discovered in the Pacific Northwest in 1924, HWA turned up in Virginia in the early 1950s. Without any natural predators to control the population, the insect spread gradually through the Smoky Mountains, north into the Hudson River Valley and into southern New England as far north as southern New Hampshire.
Reddish-purple and about 1/32nd of an inch long, this aphid-like pest could threaten the vast stretch of Canadian hemlocks that thrive throughout New Hampshire's forests by depleting the nutrient reserves in the trees leaves.
Adelgids don't like the cold. Since the first confirmed New Hampshire sighting of the bug outside a home in Merrimack in 1999, scientists have believed the cold New England winters would prevent it from spreading north. It can't survive in an area where the average temperature is below 23 degrees, but those cold temperatures never materialized this winter.
'We haven't had the snow cover this year that we typically do, but with the exception of a few days, we haven't had really cold temperatures either,'' Eaton said. 'I expect we'll see them expand their range farther in the state this year.'
Eaton says its still too early to tell whether the mild winter will trigger an increase in other pest populations.
'Everyone always asks about mosquitoes,' said Eaton. 'That has less to do with how much snow we've had than how much rain we get this spring.
'Other insects typically require snow cover to protect and shelter them through the winter months, so you may think that a mild winter would hurt those populations. But we've had such mild temperatures, the lack of snow cover may have no effect at all. We'll just have to wait and see in the weeks to come.'
Missy Henriksen, vice president of public affairs for the National Pest Management Association (NPMA) said, 'Many insects hibernate during the cold winter months, but as this winter has been anything but typical, they may be emerging from their hiding places much earlier than we expect. Several states, including New Hampshire, have even reported tick sightings, which is especially worrisome as people head outdoors to enjoy the weather and are unprepared for tick encounters.'
Insects survive cold winters by slowing down their metabolism and respiration. Warmer temperatures can wake them early from their hibernation-like state, and they wake up hungry.
The NPMA expects increased numbers of boxelder bugs in New Hampshire, multicolored Asian lady beetles and springtails, as well as increased activity in ant and termite colonies. Wasp and hornet 'future queens' may also survive the winter, resulting in more colonies in spring and summer.
State officials are not sure whether the lack of snow will hurt agricultural businesses.
'It really is too soon to tell if the dry winter will have much impact,' said Lorraine Merrill, the state's commissioner of agriculture. 'We had plenty of moisture in the ground going into the winter - you may remember some pretty wet weather in the fall - and it will really depend on what kind of snow and/or rainfall we get as the spring unfolds.''
Lack of snow cover can be detrimental to perennial field crops such as alfalfa, but that's because of lack of insulation to protect the crowns from freezing and heaving. This winter's relatively mild temperatures may keep that from being as much of a problem, Merrill said.
'The one notable difference that the milder weather has brought is the early start to the maple season,' added Merrill. 'Sap started running early, and sugar makers had been tapping and starting to boil by the first of February in many areas.'