Orange County Mosquito and Vector Control District
This website includes CSS elements that your browser does not support. Please upgrade your browser to a current version, then come back and try again.
Menu

Mosquito

Description

Red Imported Fire Ants (RIFA) are very aggressive ants that are native to South America. They vigorously defend their nests, attack in large numbers and sting repeatedly. For a small percentage of the population who are allergic to the venom, RIFA stings can be fatal.

This is also true of the very old or young as well as anyone else unable to escape the attack. For the rest of us Red Imported Fire Ants inflict painful stings that form pustules, itching for up to two weeks.

Humans are not the only ones subject to RIFA attacks; ants will be attracted to pet food left out and will sting when disturbed by a hungry pet. These attacks can be quite serious since the first part of the animal to get stung is usually the muzzle. If there are enough stings in the right place, the swelling caused by the venom can obstruct breathing.

The toll taken on wildlife can be considerable. The numbers and variety of reptiles and amphibians remaining in an area infested by RIFA is a fraction of what was there before. Any ground or low nesting birds will be impacted as well. While the Red Imported Fire Ant's need for moisture will limit the wild land infestation to wetlands, one half of threatened species are at least somewhat dependent on wetlands

The attraction of RIFA to electrical current creates a whole new set of issues. Any outdoor electrical equipment is subject to damage by Red Imported Fire Ants. Air conditioners, spas, outdoor lighting and irrigation controllers are all commonly damaged by RIFA in areas where the ants have become established.

Leg w/RIFA Bites
Damaged Air Conditioner Damaged Light Fixture

Currently, much of southern California, including all of Orange County, is under nursery quarantine. Nurseries in the quarantine area must bait survey the entire property every 90 days. They must also treat every piece of plant material they ship, regardless of the survey results. Treatment is usually done by incorporating a pesticide into the soil mix at planting time. Not only is this procedure expensive, but the amount of pesticide being used also means runoff is likely to become an issue.

Red Imported Fire Ant Educational Material (click on the thumbnail to view/download PDF)

What We Do


If you think you have found a Red Imported Fire Ant (RIFA) colony, call the Orange County Mosquito and Vector Control District (District) at once, and an inspector will be out to visit the site in a couple of days at the most. The District will determine if the colony is actually RIFA. Once RIFA are confirmed, treatment with an insect growth regulator (IGR) or a metabolic inhibitor (MI) will begin. RIFA cannot consume solid food; they filter the solids out and digest the liquid. Each of these materials is very effective at eliminating RIFA colonies. IGRs work by blocking the development of immature ants. Consequently, as the ants get older and die, they are not replaced. Metabolic inhibitors block the utilization of food. RIFA can continue to eat, but they derive no benefit from what they consume. The worker ants pass the material on to the queen.

RIFA Mound RIFA Mound 2
RIFA Mounds

IVM Products

Integrated vector management (IVM) is a decision-making process for the optimal use of resources in the management of vector populations. These decisions are made in order to reduce or interrupt transmission of vector-borne diseases, and prevent nuisance vector populations from impacting the quality of life.

The approach seeks to improve the efficacy, cost-effectiveness, ecological soundness and sustainability of vector control activities.

The key objectives of Integrated Vector Management include:

  • The selection of proven vector control methods based on knowledge of vector biology and ecology, and disease transmission.
  • Utilizing of a range of interventions, separately or in combination and often synergistically, integrating all available and effective measures, whether chemical, biological, or environmental.
  • Collaborating within the health sector and with other public and private sectors that impact vector control.
  • Engaging local communities and other stakeholders.
  • Knowledge and compliance with public health regulatory and legislative frameworks.
  • The rational use of insecticides.

The District’s management policy for Red Imported Fire Ant (RIFA) control is to use education, biological control, and chemical control within the IVM framework.

To learn more about RIFA IVM practices please refer to the District's IVM Plan.

 

Education

The District has a multifaceted RIFA education program that includes:

  • Presentations and participation in local outreach events to educate the public about RIFA control practices.
  • The creation and distribution of training DVD’s for landscape professionals to educate their staff about RIFA biology and control strategies.
  • Extensive literature on RIFA control practices, local ants that resemble RIFA, and many other publications are available in print and electronically.
  • Inspectors educate homeowners and neighborhood groups about how to identify the presence of RIFA on their property and how to eliminate them.
  • Staff attends local and national educational conferences to learn about advances in RIFA control techniques, products, and other measures to better educate and protect the public from Red Imported Fire Ants.

 

Chemical Control

The District's primary method for control of RIFA is the application of pesticide ant bait containing an insect growth regulator or toxicant. The District currently uses five pesticide ant bait formulations containing four active ingredients. The active ingredients work as an insect growth regulator (IGR) or a metabolic inhibitor (MI) as means of controlling the current adult population and emerging juvenile population. The metabolic inhibitor interferes with the metabolism of food, resulting in the death of the ants by starvation. The colony eventually dies out as a result of ants consuming the bait, then starving, and not being replaced. Results are sometimes visible within a week. The insect growth regulator essentially sterilizes the colony, as ants die through attrition, and they are not replaced. This is a slow acting material, and results may take a month or more to be recognized.

Prior to treatment, District staff confirms the identification of RIFA at a site. The District performs RIFA control in cooperation with private pest control companies at residential sites. In large area sites, such as commercial buildings, schools, parks, rights-of-way, and multifamily housing, the District performs RIFA control. In heavily infested neighborhoods, the District abates RIFA through community-wide management of the pest.

Many neighborhoods in Orange County are heavily infested with RIFA. Heavily infested neighborhoods are determined by analyzing reports of RIFA occurrence. District staff visits these neighborhoods and distributes notifications that a pesticide ant bait treatment will be made within the next week. Residents can opt out of the treatment by contacting the District or taping the notification to the door on the date of the treatment. District staff records the presence of RIFA mounds in the neighborhood. On the treatment day, pesticide ant bait is applied to the front lawns, and sometimes backyards, and communal areas of the neighborhood via a hand-held granular application device. Residents are instructed not to irrigate their property for 24 hours following treatment and to refrain from applying pesticides or other chemicals for 72 hours following treatment.

Broadcast treatments of pesticide ant bait are effective because ants from all colonies in the treated area can collect the bait. This is also easier than an Inspector trying to locate individual mounds. Pesticide ant bait not collected by the ants rapidly decomposes in the environment. Bait broadcast in the environment is effective for a short period of time as the active ingredients degrade in sunlight, and exposure to environmental factors can breakdown the food carrier.

 

What You Can Do

Because RIFA represents such a serious threat, homeowners may be tempted to treat on their own. Unlike other vector issues, the Orange County Mosquito and Vector Control District (District) discourages the public from doing anything but calling in a report. This is considered an exotic pest, and as such, must be tracked; every known site should be reported. The District Inspectors typically use an insect growth regulator (IGR), a product that inhibits development of the immature ants. This results in a decrease in replacement ants and as the workers die off, so does the colony. The active ingredients found in most pesticides that are currently available will kill ants, but not colonies. In fact, as the queen notices the effects of the poison on her workers, she will often move the entire colony. This is complicated by the fact that a single colony may have several queens, each one headed in a different direction with an entourage of workers.

Studies have shown that homeowners are far more likely to apply excess pesticides, sometimes many times the recommended amount. This results in polluted runoff and the possible removal of an otherwise effective material from the market.

Orange County residents are encouraged to be vigilant in their own yards as well as any time they are visiting a park, golf course or any place that has a large turf area. Red Imported Fire Ant colonies are distinct but southern California colonies rarely build the large mounds typical of RIFA in other parts of the country. Almost all of the mounds in Orange County are found in irrigated areas, most often turf which gets mowed every week. Look for a patch of fine granular soil where it doesn't belong; for example, in the middle of a lawn. It is possible that if a colony has settled into an irrigated planter or other landscaped area, a mound will develop, usually at the base of a shrub. Another common location is adjacent to a hardscape feature like a large rock or a concrete walkway. These large, dense objects store heat during the day and release it slowly during the night.

RIFA Mound by Sidewalk RIFA Mound by Tree
RIFA Mound by Sprinkler Heads

If you suspect you may have located a RIFA colony, do not disturb it; call the Orange County Mosquito and Vector Control District at once. A District Inspector will visit the site within a couple of days and if RIFA are confirmed, treatment will begin. Be prepared to provide as much detail as possible about the location. Simply naming the park may result in the District Inspectors failing to find the colony, or spending too much time searching. It is important to confirm the presence of Red Imported Fire Ants prior to treating, so the more detailed the directions, the better.

Vector Reduction Manual For the District's specific guidelines on how to avoid or reduce mosquitoes, rats, red imported fire ants, and flies please refer to recommendations in the Vector Reduction Manual: Procedures and Guidelines.
 Orange County Mosquito and Vector Control District