Wisconsin officials will experiment this summer with a native wasp
that could locate populations of the destructive emerald ash borer.

It would be Wisconsin’s first use of bio surveillance to search for
the elusive pest, which has killed tens of millions of trees in
Michigan, where it was first found. Infestations now range from
Maryland to Missouri.

Other states, notably Michigan, are testing Chinese wasps that are
propagated and released to kill emerald ash borers. They are natural
predators of emerald ash borers. Wisconsin officials said this week
that the state is likely to use Chinese wasps in future years.

But the native wasp, Cerceris fumipennis, is different:

• Wisconsin doesn’t need approval for its use. The Chinese wasp
requires government approvals and an environmental assessment by the
U.S. Animal and Plant Health Inspection Service.

• The native wasp can kill the emerald ash borer, but its chief value
is to search for the bug.

The work starts this summer when personnel from the Wisconsin
Department of Natural Resources will look for spots where the wasps
live – often, in holes in fields with hard-packed soil.

The initial search will start near Newburg in Ozaukee and Washington
counties.

The Newburg area is the only part of Wisconsin with a known emerald
ash borer infestation, which was discovered there last summer.

Last week, officials reported 44 different infestations, though they
believe that it has probably spread beyond the 7 1/2 -square-mile area
in and around Newburg.

The emerald ash borer was discovered in Michigan in 2002 and likely
arrived in wood packing crates from Asia. Adult beetles eat ash
foliage but cause little damage. Larvae feed on the inner bark and
disrupt the flow of nutrients.
Examine wasp’s prey

In Wisconsin, once wasp nests have been located, a DNR entomologist
will study the type of insects that the wasps bring back to their
colonies. The wasps paralyze their prey and feed them to larvae.

If the wasp is found to have an emerald ash borer, it’s a good bet
there are infestations nearby, said Jane Cummings-Carlson, forest
health protection program coordinator with the DNR.

The maximum distance that a Cerceris fumipennis flies is about 2
kilometers, or about 1.2 miles.

“This could be a really good searching tool,” said Melody Walker, pest
survey and control section chief with the state Department of
Agriculture, Trade and Consumer Protection.

Last year, the native wasp was in New England and other states in the
East.

In Maine, where the emerald ash borer has not been discovered,
scientists found that native wasps brought back to the colonies large
numbers of a broad family of beetles. The emerald ash borer belongs to
that family of beetles.

“It really worked well for us,” said Colleen Teerling, an entomologist
with the Maine Forest Service.

Until now, Wisconsin relied on traps hung on ash trees and a process
in which bark was stripped from a tree. But both techniques are
expensive and not always effective, said Walker and Cummings-Carlson.

The cost of hanging a single trap on a tree, inspecting it during the
year and then analyzing its contents in a laboratory is $110, Walker
said. The state plans to hang 7,500 traps on ash trees this year.
Traps are not magnets

The traps aren’t always magnets for the bug, however.

“The problem is that the Newburg area is infested with emerald ash
borer, and (last year) we found only one trap with three beetles in
it,” Walker said.

The second process of scraping bark from an ash tree stresses the tree
and can lure beetles looking for weak victims. The cost of the process
is $397 per tree. So-called girdled trees are eventually sawed down.
Wisconsin has discontinued this type of surveillance.

Native wasp surveillance could be cheaper, officials said, because the
wasps already inhabit Wisconsin.

A Canadian scientist who has studied the wasp as a tool for
surveillance is experimenting with mobile wasp colonies that can be
trucked to locations where the invasive beetle is suspected to live.

The size of Wisconsin’s project this year will depend on federal
funding, said Cummings-Carlson. The U.S. Forest Service has notified
the state that it will get funding, but a final figure is not known.

In the future, to control costs, Wisconsin plans to borrow an idea
from other states and work with local residents to help monitor wasp
colonies, according to Cummings-Carlson.

And while the native wasp stings its prey, scientists have found it
doesn’t appear to sting humans