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Asian Termites

Thursday, April 19, 2018   (0 Comments)

Many South Florida slash pines have stood for a century, providing shade, oxygen and wildlife habitat, as cities

rose around them. Now they face a mortal threat from tiny, wood-eating insects.

 

The Asian subterranean termite, which has been chewing its way through the local housing stock for 20 years, has

turned out to have a taste for native trees, with a particularly lethal manner of attacking slash pines, according to a

new study from the University of Florida.

 

The study, which looked at about 400 slash pines in Fort Lauderdale, found that these termites had killed 12

percent of residential trees and three percent of trees in city parks over the past five years. Another 46 percent of

the residential trees were infested, with the termites likely to cause deadly damage, according to the study,

published in the journal Florida Entomologist.

 

The park trees fared better, with 15 percent of the living trees infested. Also at risk could be slash pines in Miami-

Dade County, Palm Beach County and other parts of Broward County, where these non-native termites have

established colonies.

 

"The clock is ticking on most of our slash pines in greater Fort Lauderdale," said Thomas Chouvenc, assistant

professor of urban entomology at the University of Florida's Institute of Food and Agricultural Sciences, and lead

author of the study. "I think we're on the way to irreversibly lose most of these slash pines if we don't do anything."

In addition, these yellow-brown, half-inch long termites have attacked a wide range of other trees that constitute

the region's urban canopy, particularly live oaks. Although it doesn't kill these trees, it hollows them out, weakening

them for storms. When Hurricane Irma brushed the area last year, three live oaks hollowed-out by the termites

went down, he said. Had the termites not consumed their insides, he said, they would have withstood the storm.

With so many trees weakened by these termites, a direct hit would have been that much more devastating.

 

"These trees are being chewed up for quite a while," he said. "And we didn't have a major hurricane since Wilma in

2005. So it's been 12 or 13 years of damage that's been piling up in these trees."

 

The slash pine, named for the slashes that workers cut across the trunks to extract sap, is among the most

distinctive trees of old South Florida. Its pine rockland habitat, dry land that was perfect for real estate development,

has been largely wiped out, leaving urban slash pines scattered through parks and neighborhoods.

 

"They're one of the original canopy trees in the area," said Michael Orfanedes, Broward County extension agent for

commercial horticulture. "They're just a fraction of what they were originally because of development. They're

famous for harboring birds in their hollows."

 

Their hard wood became a popular building material known as Dade County pine, used in many sturdy older homes

that have withstood the last century of hurricanes. But this hard wood becomes a liability when hungry termites

show up. Unable to eat the sappy, hard inner wood, which is actually dead tissue, the termites turn to the live

tissue on the outer layers of the trunk. As they chew their way through this, they block the tubes that carry sugar

and other nutrients. With its vascular system disabled, the tree slowly starves.

 

Mark Torok, senior forester with the Florida Department of Agriculture and Consumer Services, said the termites

may be a serious threat but that further research is needed.

 

"It's definitely something we shouldn't ignore," he said. "But we don't have a full understanding yet about this pest.

 

Are they attacking weakened trees or are they attacking healthy trees? How aggressive are they? How much

damage do they do? Does it like any tree more than others?"

 

Native to southeast Asia, the termite is thought to have arrived in South Florida on ships and oceangoing yachts,

spreading from marinas into neighborhoods. It was detected in Miami in 1996, its first known U.S. presence, then

found in 2005 in Fort Lauderdale and Riviera Beach. They establish colonies underground. They spread by means

of swarms, when thousands of termites fly off on spring nights to found new colonies, with male and female

termites forming pairs and burrowing into trees and houses.

 

Their nighttime swarms may explain why residential trees get attacked more frequently than ones in parks,

Chouvenc said, since swarming termites are attracted to lights.

 

Although colonies can be destroyed by pest control companies, saving individual houses and trees, Chouvenc said

this go-it-alone approach won't be enough to control them in South Florida. He said area-wide management, with

entire neighborhoods cooperating, may be necessary.

 

TIPS

* To check if your slash pine has termites, look for them by peeling back a dead outer piece of bark.

* Don't bother cutting down the tree if you find subterranean termites. It won't help because most of the colony is in

the ground.

* Tenting your house won't help because subterranean termites live underground. Tenting works for drywood

termites.

* Call a pest-control company to place bait above ground at base of infested trees.

 

David Fleshler

Sun-Sentinel (Fort Lauderdale)

April 15, 2018 Sunday, 1 Edition

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