[Annual Ant Control Issue] Into The Fire

Red imported fire ants, Solenopsis invicta, are distributed throughout the states of Alabama, Mississippi, Louisiana, Georgia, Florida, South Carolina, and a large portion of Texas, as well as the more southern counties of North Carolina, Tennessee, Arkansas and Oklahoma. There are also some isolated areas of RIFA infestation in Arizona and California. Fire ants have not adapted to survive in areas where winter conditions result in sub-freezing temperatures several inches below ground, and it is currently thought that RIFA will not likely be able to extend its range into areas where winter temperatures routinely drop below 10°F. However, this does not mean that RIFA colonies can not become temporarily established in more northern areas during the warmer portions of the year. Throughout its established range, RIFA is usually the dominant, most abundant species of ant. However, another invading species, the Argentine ant (Linepithema humile), is capable of competing with RIFA.

CONTROLLING FIRE ANTS. There are many available methods of fire ant control. The choice of method depends on the size and type of area being treated and the level of control required. Most methods of control will provide significant reductions in fire ant populations, but keeping an area practically free of fire ants usually requires the use of a combination of chemical control methods. Unfortunately, there are few effective non-chemical methods of controlling fire ants.

Baits: In terms of effort and dollars spent and level of control obtained, granular baits are probably the single most effective method of controlling fire ants. These baits are formulated on some type of granular carrier that is impregnated with an attractive food material, such as vegetable oil, and a small amount of slow-acting insecticide. Although baits can be applied as individual mound treatments, broadcast applications are much more effective. This is because, in addition to the large, readily visible mounds in an area, there are usually many small, hard to detect, newly established colonies. When only the large mounds are eliminated by individual mound treatments, they are quickly replaced by smaller colonies, which thrive in the absence of foraging competition from the larger colonies.

Broadcast bait treatments target all colonies in an area, regardless of size. When using granular baits, early spring application, as soon as the soil temperature warms to above 70°F, is ideal because it controls recently developed queens before they leave on their mating flights to establish new colonies. Follow-up granular bait applications usually are necessary in mid-summer and another one in the fall, before the onset of freezing temperatures. These spring and fall bait treatments can serve as the backbone of an effective fire ant control program.

Apply baits when the ground is dry and when ground temperatures are between 70 and 90ºF with no forecast of rain. The insecticides used in granular baits are slow acting by design. Baits are picked up by foraging ants, carried back to the colony, and passed among the ants in the colony, eventually reaching and killing the queen(s). Depending on the specific bait being used, two to six weeks are usually required to obtain maximum control. Small, hand-powered spreaders are effective for applying granular baits in home lawns and other areas of limited size. Various types of electric or PTO powered spreaders are available for applying baits to larger areas. Calibration of granular applicators depends upon the type of spreader being used and the brand of bait being applied. Be sure to check and follow label and manufacturers’ directions for proper calibration. In cases where rainfall occurs within six hours of the bait application, it is usually wise to re-treat.

In summer and fall, apply bait in the afternoon when temperatures are cooler because baits may rapidly degrade on hot, sunny days. By the time ants pick up the bait, the heat may have broken down the active ingredient, reducing its effectiveness. Fire ants forage actively at night, especially during the warmer portions of the year, and late afternoon bait applications help avoid some of the adverse effects of heat. Where they are properly applied two to three times per year, baits can provide 80 to 90 percent control of fire ants. In relatively small areas, fire ant control can be improved by combining the use of granular baits with spot treatment of any individual mounds that escape the bait treatments. However, it is best to wait several days following the application of a bait treatment, before treating individual mounds. This allows time for foraging worker ants to carry the baits into the colonies and improves the odds of killing the queen. Because the oil or other food attractants in baits become less attractive once they become rancid or stale, it is best to avoid purchasing baits in large quantities that can not be used within a reasonable period of time.

Mound Treatments: Several different types of individual mound treatments are available. These include mound drenches, granular treatments and dry powders. When treating individual mounds with any insecticide, do not disturb mounds before treating. If you do, the colony will immediately take the queen, or queens, to safety, either deep down in the mound or move them laterally to establish satellite mounds. When using liquid drenches as individual mound treatments, use 1 to 2 gallons of liquid per mound, depending on the size of the mound and be sure to thoroughly drench the mound as well as an area about 12 inches around the periphery of the mound. This is done in order to place insecticide into the many exit tunnels that radiate from the mound.

When using dry mound treatments, simply sprinkle the appropriate amount of material on, and around, the mound according to label directions. Liquid drenches have the advantage of providing quicker control, but they are sometimes troublesome and time consuming to mix and apply. Dry mound treatments are slower acting, but are more convenient and easy to apply. Some granular insecticides also are labeled as mound treatments, but these usually require drenching the mound with one to two gallons of water after the granules are applied.

In highly sensitive areas, such as pet yards or play yards of very young children, where it is necessary to promptly eliminate a fire ant mound but undesirable to use insecticides, individual mound drenches with boiling water can sometimes be used effectively. This approach is most likely to be successful during cool, wet periods of the year, when ants, and the queen(s) and brood, are more likely to be concentrated in the above portion of the mound.

It is necessary to use a high volume, two to three gallons, of near boiling water and thoroughly drench the mound as previously described. Obviously this approach will damage the grass and any plants in the immediate vicinity of the mound, and there is the risk of burns, but there is no chemical residue.

Baits may also be used effectively in such sensitive areas, either by spreading them around the periphery of the area and depending on the foraging activity of the ants, or by spreading them directly in the area and avoiding its use for a few days. While baits are slow acting and will not result in the immediate elimination of a problem mound, their proactive use can play an important role in helping to keep such sensitive areas free of ants.

Broadcast Insecticide Treatments: Broadcast insecticide treatments may be formulated for application either as liquid sprays or as dry granules. However, the granules used for broadcast insecticide treatments should not be confused with granules that are formulated as baits. Broadcast insecticide granules do not contain any type of food attractant and will not be attractive to foraging workers. In this case the granule serves only as a carrier for the insecticide, which is usually faster acting than the insecticides used in bait granules.

Once the granules are applied to the soil surface, the insecticide moves into the moist soil where it provides residual control of any ants that contact it. In most cases, the label for broadcast granular insecticides requires that the treated area be watered following application of the granules. Broadcast treatments that are applied as liquid sprays provide residual control in a similar fashion. Such treatments are normally applied using pressurized spray equipment.

The primary objective of using broadcast insecticides is to kill foraging workers and newly settled queens that are attempting to establish new colonies. Many of the insecticides used as broadcast treatments for fire ants also provide control of other lawn and turf insects, provided they are applied at an appropriate time. Where fire ants are the primary target, broadcast treatments are best used as a supplement to bait treatments. In order to provide the most effective control, most insecticides used in broadcast treatments must be re-applied every six to eight weeks. Treatments containing the active ingredient fipronil provide longer control.

Multiple Methods, Timing and Persistence. In highly sensitive areas, such as athletic fields and other areas where the tolerance level for fire ants is essentially zero, reaching and maintaining this high level of control requires a relatively high level of management involving multiple control methods. Broadcast bait treatments applied in spring and fall can serve as the backbone of an intensive fire ant control program but they must be supplemented with broadcast insecticide treatments, and, when necessary, individual mound treatments. In home lawn situations where there may be a slightly higher tolerance level, broadcast baits applied in the spring and fall, and possibly during mid-summer, and supplemented, when necessary, with individual mound treatments may provide acceptable control.

Fire ant control is a never-ending effort because managed turf and landscape areas are continually being re-infested by swarming queens that emerge from mounds in nearby unmanaged areas. When swarming queens attempt to establish colonies in areas that are already heavily infested with other fire ants, they often are preyed upon by the ants that were already present. However, when swarming queens attempt to establish colonies in areas that are free of other fire ants, their chances of success are much higher because of the absence of competition. Timing and persistence are the keys to maintaining a turf or landscape area that is relatively free of fire ants.

SENSITIVE ACCOUNTS. Where fire ants are concerned, the term "sensitive account" can refer to a variety of different situations. It could be the home lawn of an individual who has a known hypersensitivity to fire ants, or the lawn of an individual who wishes to avoid fire ants, but also has an aversion to chemical pesticides. Play yards for child day-care facilities and home lawns where very young children play would also fall into this category.

However, this portion of the article will focus specifically on fire ants in sensitive indoor facilities. Here the focus is primarily on those facilities that house individuals who are especially susceptible to fire ants because they are incapacitated in some way, due to infirmity or age. This would include hospitals, nursing homes, infant day-care facilities, and other, similar types of facilities.

As mentioned previously, fire ants do not normally occur indoors, but they do occasionally invade indoor facilities as foraging workers, or as entire colonies that are forced to relocate due to some type of adverse condition. When invading fire ants come into contact with individuals who are unable to react because they are incapacitated, or are even unaware that they are being attacked because they are unconscious, there is potential for serious stinging incidents to occur, and there have been cases of fatalities resulting from such events.

Because such indoor invasions of fire ants are difficult to predict and can occur over a relatively short period of time, it is doubtful that they can ever be entirely prevented. However, a carefully planned and executed effort to control fire ants in the landscape area immediately surrounding the vicinity of the building can greatly reduce the potential for indoor invasion, and vigilance and prompt action by care facility personnel can help minimize problems caused by colonies that do invade buildings.

Pest control operators who have indoor pest control contacts with such sensitive accounts should have a clearly outlined agreement with facility managers regarding fire ant control expectations. There is considerable extra expense involved in preventively controlling fire ants outside the building, and this should be taken into consideration. If the PCO involved does not have the appropriate license to apply fire ant treatments in a landscape situation, or simply does not wish to perform this type of work, then it will be necessary to coordinate with a landscape management service that understands the special concerns associated with such sensitive accounts.

CONTROLLING FIRE ANTS. Control of fire ants in the landscape surrounding a "sensitive account" is similar to fire ant control in other situations. The key difference lies in the intensity of the effort. The goal is to prevent fire ant colonies from becoming and/or remaining established in the vicinity of the building. Because ant mounds that are located nearest the foundation of the building pose the greatest potential for an indoor invasion, special attention should be focused on preventing the establishment of fire ant mounds within the immediate vicinity of the building. Application of a broadcast insecticide treatment in band at least 25 to 50 feet wide around the perimeter of the building can be helpful in this regard.

This broadcast insecticide treatment should be supplemented with broadcast bait treatments applied in spring and fall, and possibly at other times of the year. In order to minimize the total fire ant population in the area as much as possible, such bait treatments should be applied over the entire grounds, including the immediate perimeter of the building. Routinely patrolling the grounds for the presence of fire ant mounds and spot treating individual mound treatments when needed is the third component of a fire ant management effort around sensitive accounts. Flexibility and responsiveness are also key components. If it is determined that fire ants are becoming re-established in the area, additional broadcast bait treatments, and/or supplemental broadcast insecticide treatments may be required.

CONCLUSION. When carrying out a fire ant management program around a sensitive account be sure to consider "unconventional" or easily overlooked nesting sites. This could include interior courtyards, potted plants, interior plantscapes, and even roof tops if there are situations where there is an accumulation of soil-like material (rotting leaves, etc.) and adequate moisture. It is also important to consider potential routes that fire ants might use to enter buildings and take steps to block, or treat these as appropriate.

In cases where fire ants do invade the building, they have to be dealt with immediately, using standard treatments labeled for use in the site. Contact insecticides labeled for use against common indoor ants will also be effective against fire ants.

After the immediate threat is removed, the next question to ask is "where did they come from?" Foraging workers probably originated from a mound located just outside the building, but they could also indicate the presence of a colony that has recently invaded the building.

Such colonies must be found and eliminated or future problems are likely to occur. If a colony invaded a building in response to adverse environmental conditions, too wet or too dry, then other colonies are also likely to be forced to move. Therefore, a problem with one invading colony should be a trigger to patrol the outside perimeter of the building for other potential problem colonies.

The author is an extension entomologist at Mississippi State University. He can be reached at blayton@pctonline.com.

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Bayer ES Hosts Fire Ant Summit To Discuss TopChoice

About 200 pest management professionals and lawn care operators earlier this year attended the Bayer Environmental Science (ES) TopChoice Summit in Orlando, Fla. The focus of the event was the introduction of Bayer’s TopChoice, an ultra-low dose granule. TopChoice, which features fipronil, controls red imported fire ants , mole crickets, fleas, ticks and nuisance ants for up to one year, the company says.

On the first day of the conference, attendees heard from several speakers, including a technical review of Bayer ES by Dr. Nick Hamon, director, development and technical services, Bayer ES; Tim Davis, a Clemson University graduate and fire ant county extension agent; and Laurence Mudge, field development and technical services representative, Bayer ES.

Davis spoke to attendees about why fire ants are difficult to control. He noted that these ants move their colonies easily and quickly, they have the ability to produce many offspring and they are an invasive species that have no natural enemies in the U.S. On the second day of the conference, Bayer representatives discussed the public’s perception of fire ant problems and control options, TopChoice marketing initiatives, and the program featured a panel discussion about fire ant control. For more information, visit www.bayerprocentral.com.