Beetles Chew Through Drought-Weakened Pine Trees
by: Jack Williams, October 15, 2009 5:10:38 pm
"This is what nature does. The bark beetle is very good at what it does."
Michael Murphrey knows firsthand how devastating pine bark beetles can be. He's a forester with the Texas Forest Service and says the beetles work quickly, killing trees in as little as four days.
"They get inside. They lay their eggs. Inside there, they brood their larva, crawl around in there. They eat the inner layers of the bark. They develop an outbreak number of the beetles that winds up eating all the tissue which girdles the tree, which forces the tree to die."
The beetles are attracted to the smell that weak, stressed trees give off. Once the bugs have done their work, pine trees quickly turn brown and die. Here in Houston, the bark beetles have been active, mostly because of the dry summer. Victor Cordova is the city's forester.
"The park that is hit the hardest is Memorial Park, and that's maybe 100 trees or so. It's been spotty in Stude Park, some of our pocket parks, Hermann Park. It's bad, but it's not as bad as it's been in the past."
Cordova says in the late 90's, more than a thousand trees died here as a result of pine bark beetle infestations. In the city of Piney Point Village in the Memorial area, forester Cary Moran says pockets of trees have died. In one case, a homeowner lost a dozen pine trees.
"We lost a lot of pines out here in Hurricane Ike, so it's terrible to see these trees that have gone through Hurricane Ike, the ones that didn't fall over and are now succumbing to the beetle infestation."
Moran says there are ways to prevent pine bark beetles from killing pine trees.
"I've recommended all through the summer that residents who were worried about their large trees to put a hose out underneath the tree and let it do a slow drip all night and in the winter I'd recommend fertilization of the trees. The best thing to keep the beetles from attacking your pine is maintenance and keeping them in good health. That's really
Once the beetles have done their work there's not much you can do though. Louis Flory own Ability Tree Experts here in Houston.
"The tree can still be green and when you look up and you have the entering and exiting tubing holes in the trunk of the tree and the sawdust accumulating all in the crevices and cracks of the bark of the tree there is no chemical cure from that point. It's recommended by leading arborists and foresters to have the pine trees cut down and disposed of and then spray the immediate pine trees within a 50-75 foot radius area."
He says certain insecticides can help fight-off the beetles, but other experts aren't so sure even chemicals can do much to stop them. The good news, with the recent rains, it looks like the worst of the pine bark beetle problem may be over.
Above image from the Texas Agricultural Extension Service Archives, Texas A&M University, www.insectimages.org.