By Bruce Scruton
MIDDLE SMITHFIELD, Pa. — Three species of a small wasp that can attack the eggs of the emerald ash borer were released by National Park Service biologists within the Delaware Water Gap National Recreation Area this past weekend.
The borer, an invasive beetle from Asia, is capable of killing a full-grown ash tree within a couple of years and has been found in several locations in Sussex County in the past two years.
The release was in the Mosier’s Knob area, just below the Walpack Bend of the Delaware River and across the river from Worthington State Forest where the New Jersey Department of Agriculture recently released its own biological agents to stem the invasion of the pest.
Kara Deutsch, chief of resource management for the park, said the emerald ash borer has been found on both sides of the river. The choice of Mosier’s Knob for the release came at the recommendation of regional NPS experts.
The wasps, known in scientific circles as “parasitoids,” were supplied by the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) and came from the Plant Protection and Quarantine (PPQ) EAB Parasitoid Rearing Facility in Brighton, Mich.
There were three species of wasps released — one release was of adults and the others were pupae of separate species.
The three are themselves invasives, native to the Asian areas where the emerald ash borer are native. The borer was imported to this area first identified in the area around Detroit and believed to have arrived in 2002 inside of wooden packing material.
In less than two decades since, the borer, a type of beetle, has been found in the U.S. from the Atlantic Coast (except Forida) as far west as Colorado and has spread throughout the eastern two-thirds of Canada.
The wasp parasites — the adults are about the size of a mosquito and don’t sting — get the borer in both egg and larval states.
The adult Oobius agrili female will lay her own egg inside the egg of an ash borer and there are two life cycles of the wasp for one life cycle of the borer. In experiments and observation, more than half an emerald ash borer’s eggs became victims of the wasp.
The other two wasps attack the larval stage of the borer and it is that stage that causes the damage to ash trees.
By Andy Newman
Though it appears destructive, fire in the New Jersey Pinelands is a force of renewal.
On April 22, a spring wildfire roared through Penn State Forest in the New Jersey Pine Barrens, sending 100-foot flames shooting from the crowns of the pitch pines. The fire consumed half a square mile in 40 minutes and could be seen from space. By the time the New Jersey Forest Fire Service got it under control, it had burned 843 acres, an area the size of Central Park.
A week later, even as ash still swirled through air heavy with the creosote scent of burned resin and a cedar log smoldered at the edge of a swamp, the forest was being reborn. Pine cones that open only under extreme heat had released their seeds. Though the trees themselves were charred, almost all survived the fire. Where chest-high blueberry and huckleberry had burned down to pointy stubs, tufts of grass were sprouting.
Destructive fires in the West dominated the news this summer, but for eons fire has been not just an inevitable feature of the landscape, but essential to the forest’s health and continuity. In the vast wilderness of the Pine Barrens, the forest regenerates so fast that scientists studying the physics of fire use it as a laboratory.
Eleven weeks after the fire in Penn State Forest, at the height of summer’s greening, new blueberry bushes were already shin high. A grass that flowers only after fire had put forth purple-brown seeds. And scattered all through the fire site, bursts of bright-green pitch-pine needles grew straight out of scorched trunks.