Insect Problems Follow Floods

Dale K. Pollet, Ring, Dennis R.  |  9/1/2005 1:54:01 AM

Certain insect problems increase dramatically after flooding, windstorms and other disasters, according to entomologists with the LSU AgCenter.

“Homes are subject to fire ant problems during and after flooding,” says LSU AgCenter entomologist Dr. Dennis Ring, adding, “Fire ants often will float around in water and attach themselves to whatever is out of the water.”

Ring says that Acephate (Address, Orthene) and baits may be applied to control these pests, and he says bait applications inside the house and acephate along the outside perimeter of the house usually will take care of the problem.

“As floodwaters recede, higher grounds may become heavily infested with fire ants,” Ring says.

If these infested areas are where people will be living or working, entomologists say the areas can be treated with one of several baits either by broadcast treatment or by using about 1 tablespoon to 5 tablespoons per mound. They also can be treated with a drench treatment consisting of 1 tablespoon of 75 percent Orthene per 1 gallon of water or applying 1 teaspoon to 2 teaspoons of the material per mound, the entomologists say.

Ring says to pour the drench mixture on the mound slowly so it will penetrate down into the colony –using 2 to 3 quarts per mound.

Another problem that can follow flooding are large groups of wasps found in yards and around plants, says LSU AgCenter entomologist Dr. Dale Pollet, who explains the wasps feed on grubs in the soil.

“High water pushes these grubs closer to the soil surface, and they are more available to the wasps,” Pollet explains, adding, however, that the wasps he saw during the state’s last bout of major flooding were Tiphiids, which do not sting. “Whether they would sting is a major concern for people who see them in their yards, but they usually hover just over the surface, fly quickly and are very seldom observed landing.

“But we realize the high numbers in certain areas create anxiety.”

Other problems after flooding or storms also have been known to come from filth flies, blow flies and smoky brown cockroaches.

For example, the entomologists say adult flies will lay eggs in decaying or rotting food materials. The immature fly larvae, called maggots, hatch in one or two days, feed for five to 10 days, then pupate. Then more adults emerge in as little as seven to eight days, producing large numbers of flies.

“Sanitation and cleanup are important in preventing the flies,” Ring says. “If such problems occur, spray wall surfaces with malathion or other household insecticides. In kitchen areas, use space sprays that contain pyrethrins to kill flying insects.”

Smoky brown cockroaches usually live outside and come inside to feed, according to entomologists.

“However, during heavy rain, they may invade houses in larger numbers,” Pollet says. “Applications of insecticides containing permethrin may be made to infested areas and around doorways, windows and so forth on the outside.”

Most labeled household insecticides will be effective against the smoky browns, the entomologists say, adding, however, that you may want to call a professional pest control operator for additional assistance in combating some of these pests.

In another area of insect problems, the LSU AgCenter entomologists point out that trees often are damaged during a storm, which gives entry to such insects as wood borers, Southern Pine beetles, Ips beetles and so forth.

“Those insects will attack an injured or weakened tree much more readily than they will a healthy one,” Pollet cautions, adding, “Sometimes tree roots will be damaged during a windstorm, and the tree may not show symptoms for several months.”

Injured pine tree trunks should be sprayed thoroughly with Permethrin, the entomologists recommend.

Carpenter ants also will frequently infest broken limbs and invade houses from infested trees after a storm. These insects do not feed on wood but simply nest in the wood. In general, they are scavengers.

“Control of carpenter ants can be obtained by removing tree limbs and branches from roofs and making sure no limbs come in direct contact with the house,” Ring says. “But if problems persist, it may be necessary to spray infested areas of the house with a 0.5 percent solution of malathion or use a bait.”

In addition, the trunks of infested trees may require spraying to control the pests in the house, he says, adding that the bottom 1 foot to 2 feet of the house also may require spraying if problems persist.

Moving to another insect problem, Pollet says yellow jackets are highly attracted to sap from trees, sugars and souring foods, and they often will attack people around such objects.

“Yellow jackets also are attracted to people sweating and will sting if disturbed,” he cautions.

To control yellow jackets, the entomologists recommend surface applications of 1 percent malathion.

“When working in the yard, keep a pressurized can containing pyrethrin handy to spray the flying yellow jackets and honeybees if they attack,” Pollet says, adding, “Areas containing sour foods should be cleaned and washed thoroughly. If necessary, make a residual application of malathion.”

Some hardwoods, especially pecan wood, are susceptible to such wood borers as the long-horned beetles. So the entomologists say when you are cutting storm-damaged trees for firewood, be sure to cover the wood so rain does not continue to keep the wood wet, encouraging borer survival.

“Under good, dry conditions, oak wood will carry over from one year to the next,” Pollet says. “Pecan firewood, even under dry conditions, does not carry over from one year to the next very well. So try to burn pecan wood during the first year it has been cut.”

On the other hand, Ring notes borers that attack firewood rarely infest houses.

For more information on cleaning up after a storm or controlling insects around your home, contact your parish LSU AgCenter Extension office or visit the LSU AgCenter's website.

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