Cold Winter Won't Mean Escape From Pesky Invaders

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    NEWSLETTERS

    Emma Lee for NewsWorks.org

    To the list of people who had high hopes for this past New Jersey winter — cross-country skiers, outdoor skaters, ice boat sailors — add the foresters trying to save New Jersey's Southern pine forest.

    They, like the rest of us, were hoping that the cold winter and heavy snowfall might have killed off the Southern pine beetles, not to mention the mosquitoes and stinkbugs that plague New Jerseyans and visitors in the summer.

    But experts said it's unlikely the coldest winter in years will do much to change the balance of nature here.

    "You need consecutive days of minus 7 to 8 degrees" Fahrenheit to effectively kill off the larvae of Southern pine beetles that have already killed thousands of trees in the southern Pine Barrens, Ron Corkory told the Asbury Park Press. He's the southern pine beetle coordinator for the state Department of Environmental Protection.

    As for mosquitoes, experts say we won't know until spring — although they warn that Sandy-dilapidated housing could prove a breeding ground for the aggressive Asian tiger mosquitoes. And stinkbugs are likely still hiding in people's homes, so the jury's out until spring on them as well.

    Since it was identified in 2002, the northward-moving pine beetle has wrecked up to 14,000 acres of trees in a year, with recent years running between 6,000 to 8,000 acres annually. Most victims are loblolly and shagbark pine, close relatives to the trees of the Southeastern United States where the beetles started their feast.

    At first glance, the Southern pine beetle is not very impressive. A brownish-black insect just 2 millimeters to 4 millimeters long, it's about as half as big as a rice grain and resembles a small fly when it's on the wing, foresters say.

    But it's among a group of aggressive "bark beetle" species that bore into tree trunks, tunneling under the bark and cutting off the flow of moisture and nutrients through the cambium, the first layer of tissue under the bark. They leave trees riddled with holes and infected with a fungus that the beetles often carry. Disruption of the sapwood cuts off water flow inside the trees and can kill them in days.

    "It depends on so many factors," Corkory said. "We're never going to eradicate them."

    The strategy is to hold the pests south of the Mullica River in Burlington and Atlantic counties, to prevent a breakout into the vast public forests and suburban woodlands of Ocean County.

    Mosquitoes operate almost entirely on spring conditions no matter what winter brings. The North Slope of Alaska is one of the worst places in the world for mosquitoes. Not to be outdone, their New Jersey cousins fared pretty well through this winter.

    "These species are adapted to these conditions," said Michael Romanowski, superintendent of the Ocean County Mosquito Extermination Commission. In their early-season surveys of wooded wetlands where freshwater mosquitoes breed, early April water temperatures were 36 to 38 degrees Fahrenheit — the temperature of a kitchen refrigerator — "and believe it or not we found mosquito larvae," Romanowski said.

    It takes warmer weather for them to grow — brief winter excursions of warm temperatures brought woodland pools up to the 50s in February before plunging back to the 30s, Romanowski said.

    Now much will depend on what spring brings in rainfall and temperatures. Commission workers are out in three trucks and two helicopters doing their early surveillance and treating water to prevent big hatches.

    But the big questions lie not in the woods but waterside neighborhoods still lying wrecked by Sandy. Unoccupied houses with debris still in their yards, and the ubiquitous blue plastic tarps to cover leaks, can hold water for breeding mosquitoes, especially the invading Asian tiger mosquito.

    "The Asian tiger is a whole different thing. They're breeding in container situations around people's houses. A little bottle cap under a shrub can provide habitat for them," Romanowski said.

    Instead of massive spraying programs, public health officials see "the best offense is a good defense" against Asian tiger mosquitoes, Romanowski said. His office offers a "yard audit" service to Ocean County residents, sending out workers to find mosquito breeding spots and telling residents how to prevent them.

    Fruit farmers and homeowners throughout the mid-Atlantic had been hoping for a winter to kill off stinkbugs, a noxious invader that likes to take cold weather refuge in human habitation — and emit offensive squirts when the owners disturb them.

    "The jury's still out. Many of them are inside yet, in barns and sheds and people's homes," said William Sciarappa, the agricultural agent for Monmouth County with the Rutgers University Cooperative Extension Service.

    Rutgers advisers counsel farmers on using a system called integrated pest management, or IPM, to reduce the use of chemical pesticides and more biological controls, like other insects that feed on agricultural pests. Some of that has gone out the window because stinkbugs got so bad, he said.

    "The last year or two we've had a reduction in numbers. I suspect it's because the farmers sprayed like crazy," Sciarappa said. "It's kind of messed up our IPM program." But there are some signs that natural predators, like some birds and predatory wasps, may be developing a taste for stinkbugs, he said: "Hopefully the biological controls will kick in."

    "We haven't had this hard of a winter for a decade," Sciarappa said.