Termintes:

Subterranean Termite Treatment

Introduction

Subterranean termite treatment has changed dramatically over the last two decades. The number of systems, application techniques and products available for termite control has tripled in the last 10 years. Today, if you experience a subterranean termite swarm, you may call four different pest management companies and receive four completely different treatment recommendations

Subterranean termite workers.
Prevention

Subterranean termites feed exclusively on wood materials and have strict moisture requirements. With these characteristics in mind, a lot can be done to prevent an infestation by eliminating the food and moisture resources in their environment. Listed below are a few practical ways to prevent termite infestation by modifying their habitat.

Repair structural and plumbing leaks.

Pull all mulch and landscaping back at least 6 inches from the foundation.

Remove piles of trash and debris from around the home.

Remove dead tree stumps from the yard.

Keep firewood stacked away from the structure.

Make sure downspouts are long enough to direct water away from the foundation.

Keep gutters clean.

Avoid direct wood-to-ground contact when building porches or decks.

Siding, brick veneer, or foam insulation should not extend below the soil grade.  

Subterranean Termite Treatment

Subterranean termites are widespread throughout the United States. Because they are so abundant, prevention alone may not always protect a structure from infestation. If a structure has become infested, additional action must be taken. Over the past few years, the number of subterranean termite treatment methods has increased dramatically. Below is a description of the most commonly sold methods of termite treatment in Virginia.

Liquid Termiticide Applications

Liquid termiticides are usually applied completely around and underneath a structure covering all areas where termites might gain access. For new construction, this is accomplished by treating the graded soil and foundation walls before the slab is poured. For an existing building, the perimeter of the foundation is trenched and drilled, then treated with termiticide. The goal of the treatment is to put a chemical blanket between the termites in the soil and the structure above. The chemical blanket can also affect those termites inside a building by preventing their successful return to the soil. In many cases, these termites will die of dehydration. PMP drilling the steps so that he can inject liquid termiticide against the foundation wall.

Repellent Termiticides

There are several repellent termiticides on the market. These termiticides are all pyrethroids. Pyrethroids are fast acting nerve poisons that are highly toxic to termites but have low toxicity to mammals. Some of the pyrethroid termite products include Dragnet FT, Cynoff, and Talstar (FMC Corporation, Philadelphia, Pa.) and Demon and Prelude (Syngenta, Inc., Greensboro, N.C.). The pyrethroids are also highly repellent to termites. In most cases, they are so repellent that termites foraging under the soil will avoid coming into contact with the termiticide and forage elsewhere.

There are advantages and disadvantages to repellent termiticides. One advantage is that a complete barrier of repellent termiticide will effectively keep termites from coming into the structure. Also, the pyrethroids used for these barriers are relatively inexpensive and last for several years. The disadvantage is that termites are able to detect these termiticide barriers in the soil and avoid lethal contact with them. This is important because applying a perfect barrier under a fully constructed house is very difficult. Construction features, plumbing lines, and landscaping are just a few of the obstacles that hinder liquid termiticide application. Because of these difficulties, there are often gaps in the treatment where the termiticide was not applied completely. Eventually, foraging termites may locate these gaps and gain access into the structure. If these termites find the structural wood, they will tunnel back and forth through the untreated gap and recruit other termites into the building.

Non-Repellent Termiticides

At the time of this writing there are a few non-repellent termiticide treatments available on the commercial market. These chemicals are not repellant and termites cannot detect them in the soil. Therefore, the termites tunnel into the termiticide while foraging, contact the chemical, and die.

Termidor (BASF Corporation, Research Triangle Park, N.C.) is also a non-repellent termiticide. The active ingredient is fipronil. Fipronil is unique in that it can be transferred from one termite to another through contact and trophallaxis (communal feeding). This allows it to affect more termites than those that contact the chemical directly. The advantage of this product is its long-term effectiveness in the soil. Test data indicate that fipronil may be effective longer after the initial application than other liquid termiticide products. A disadvantage is that Termidor is more expensive than other liquid termiticides.

Liquid Termiticides

Advantages

Intended to provide immediate protection for the structure

Lasts multiple years in the soil

Non-repellent termiticides eliminate the problem of termites locating “gaps” in the treatment

Relatively inexpensive compared to baiting systems  (see below)

Disadvantages

Liquid termiticide applications can be slightly disruptive to the structure, requiring that porches, stoops and even the slabs be drilled through at 12-16” intervals so that the liquid can be injected into the soil along the foundation walls.  Even though these drill holes are later plugged, they are still visible after treatment.

Subterranean Termite Baits

Termite baiting takes a very different approach to subterranean termite control than liquid termiticide application. Instead of attempting to protect a structure by creating a chemical blanket between the building and the termites, baiting targets the termites themselves. Termite baits are designed to suppress or eliminate the termite colony living in the soil.

The first commercial termite baiting system became available in 1995. Since that time, several termite bating systems have been developed.  The most widely used bait products are applied very similarly. The initial installation of any baiting system involves plastic stations being inserted into the ground around the periphery of the structure approximately every 10 feet. Inside these stations are untreated wood monitors. The stations are usually inspected either once a month or every 3 months (quarterly) for termite activity. If live termites are found in the station, a toxic bait will be placed inside and the infested monitor may or may not be removed. The idea is to get the termites that have been recruited to the wood monitor to now pick up the bait instead. Certain bait products are intended to be used by themselves, while others can be used in combination with a spot applications of liquid termiticide (applied only to areas where termites are active) or a complete liquid treatment.

Because the in-ground bait stations are placed outside the structure, they do not directly affect termites that are already foraging inside. To address these inside infestations, certain manufacturers provide above-ground stations. Above-ground stations are basically plastic boxes that contain a paper matrix (bait) laced with the active ingredient (toxicant). The boxes can be attached over a termite mud tube or directly onto infested wood. The termites forage inside the box and consume the paper bait. Major components of the Sentricon Termite Baiting System.

The following is a description of the most widely used baiting systems available on the commercial market.

Sentricon System – The Sentricon system was the first termite baiting system commercially available. It is now the most widely used bait system within the United States and internationally. It was developed in 1995 by Dow AgroSciences (Indianapolis, Ind.) and the University of Florida as a stand-alone bating system.  Sentricon was not intended for use in combination with liquid termiticide because at the time of its development, only repellent termiticides were available. If a repellent termiticide contaminated a bait station, termites would turn away from the station, rendering it useless. However, now that non-repellent termiticides are available, Sentricon can be used in combination with a non-repellent termiticide.

The bait system consists of in-ground stations that contain 2 pieces of untreated wood (“monitors”). The stations are checked at first monthly and then on a quarterly schedule to see if termites have invaded or “hit” the monitors. If so, the termites are collected from the monitors and placed inside a tube of bait. The bait then replaces the monitors in the station and the termites must then eat their way out of the bait tube.

The Sentricon System is marketed as a termite colony elimination system. In order for a colony elimination system to work, the bait must affect almost every termite in the colony. Worker termites do all of the foraging, so how does the bait get from the worker termites to the rest of the colony? Remember that the worker termites are responsible for feeding all of their nest mates. They do this by consuming food themselves then regurgitating part of it into the mouths of the other colony members. This same natural behavior is exploited by the Sentricon system to disperse the bait toxicant throughout the termite nest. It is important to note that the bait cannot work too fast. If the active ingredient killed the termites too rapidly, the worker termites would die before they could pass the bait to other colony members.

The active ingredient in the Sentricon bait is noviflumuron, a slow acting toxicant. Noviflumuron is an insect growth regulator (IGR). IGRs interfere with the insect’s physical development. This particular IGR interferes with the insect’s ability to molt. Insects have their skeleton on the outside of their bodies, an exoskeleton. In order to grow larger they must periodically shed this exoskeleton in a process called molting. Noviflumuron does not allow the termite to molt properly, so it dies in the process. When noviflumuron is passed from one termite to another, the affected termites die during their next molt. In time, there are too few termites left to take care of the colony and feed the queen. When the queen dies the colony is eliminated.


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