Little Fire Ant FAQs

The Little Fire Ant (Wasmannia auropunctata) is known by many names around the world, including cocoa-tree ant, little red fire ant, or electric ant (because stings have been compared to the feeling of an electrical burn).   It is native to South America but has invaded tropical and sub-tropical regions around the world from Africa to Israel to Australia to the Galapagos Islands. It is even known as a greenhouse pest in colder areas such as Europe and Canada! LFA can be transported easily through many kinds of personal and commercial cargo.

Through DNA studies, we can see that the LFA we have now in Hawai‛i is most closely related to invasive colonies in Florida. It is thought that they were accidentally introduced to Hawai‛i Island on shipments of plants to nurseries in Puna sometime in the 1990s.

There have been over 50 ant species introduced to Hawaii, some of them stinging ants.   The Tropical Fire Ant (Solenopsis geminata) has been in Hawai‛i for many decades. This is a fast-moving, ground-nesting red ant that also has a bad sting. However, TFA do not spread as readily as LFA, and their colonies are more easily treated, as they are not as mobile. Tropical fire ants are much larger than LFA and usually sting around the feet and ankles when disturbed. LFA are very small and slow-moving and are known to sting around the shoulders and neck as they can fall from vegetation above you. Here is a document with a good comparison. 

In 1999, a Hawaii Department of Agriculture entomologist collected a sample of stinging ants in lower Puna that appeared to be new to the island. He was able to identify the ant as LFA, and the search was on to find out if the ants had spread to other locations.

By 2002, surveys showed that positive detections of LFA from Kalapana to Laupāhoehoe, indicating they had spread far beyond the point of eradication. LFA are notoriously difficult to treat because they utilize trees to travel, and it was very difficult to get pesticides into the trees to where ants will come into contact with them.

The state Department of Agriculture is now charged with preventing the spread of LFA to other islands, and they perform inspections of goods being shipped inter-island. The Hawai‛i Ant Lab (HAL) researches methods for control of LFA and pursues new products and treatments for use in our unique Hawaiian landscape.  On outer islands, staff from HDOA, HAL, and the local ISCs will work together to eradicate newly discovered populations of LFA, so all homeowners on other islands should be surveying regularly and detections should be reported immediately. On the Big Island, HAL and BIISC offer training programs to residents for LFA treatment.

Hawai‛i has no native ants, and while most ant introductions are fairly harmless, several of them can pose a threat to our environment, our livelihoods, or our health. LFA are a problem in all three areas. The World Conservation Union (IUCN) of the United Nations has labeled LFA one of the top 100 worst invasive species in the world.

Other species of ants already wreak havoc on our native bird populations. In the Galapagos Islands, LFA attack, blind, and kill endangered baby tortoises. If LFA were to spread into the habitats of our threatened and endangered native Hawaiian birds, it could be devastating for the animals we’ve worked so hard to protect. Even our pets are not safe: LFA will attack the eyes of cats and dogs, resulting in the formation of cataracts that lead to blindness.

LFA have a burning fiery sting that leaves itchy, painful welts that can last for weeks. They form nests wherever there is shade and adequate moisture, especially in trees. But because they can’t grip very well, they tend to fall from trees and rain down on unsuspecting people and animals, resulting in dozens or sometimes hundreds of stings. This can make picking fruit and doing yard work a painful experience. Unlike other ants, LFA will work with neighboring LFA colonies to form massive supercolonies. These supercolonies can force out other ants and insect species. Without treatment, LFA rapidly expand in population: densities in Hawai‛i can reach 20,000 ants per square meter. At this level, LFA will completely take over yards and homes.

Ants are social, cooperative insects. The queen is the reproductive source, and each LFA colony can have many queens. They can produce multiple eggs a day that develop into two different kinds of pupae: worker pupae and reproductive pupae. There are fewer reproductive pupae, and they become males or queens. Most of the pupae, however, are the worker type, as hundreds of thousands of worker ants are needed to care for the colony. Their job is to take care of the queens and the larvae, to protect the nest, and to forage for food and water to bring back to the ants inside the nest. The worker ant life cycle is about 3-4 months, although queens can live much longer (possibly several years!)

LFA are not builder ants. They will not form mounds or dig complicated tunnels. They much prefer to move into ready-made spaces that provide a bit of shade and moisture, such as rock walls or within the fronds of palm trees, under the moss on the bark of a tree or under some discarded planters in the backyard. They are readily adaptable to a variety of tiny habitats.

Although it may seem as though the ants suddenly arrived, it is actually quite probable that they’ve been quietly building their numbers for months or even years before becoming noticeable. The ONLY way to be sure you don’t have LFA on your property is to survey properly.
You should also try to prevent accidental introductions. LFA don’t travel very far on their own: they are normally first introduced to a new location when people bring them in with things, like potted plants or building materials. They can also fall from overhanging trees or get washed into your property with the rain. LFA perform something called rafting, where they group together and float when submerged in water.

On their own, they spread slowly, but people and nature can speed up their spread immensely. Once the colony’s population reaches a certain point, a queen will move a few feet to yards away with a few workers and start a new colony. This is called budding, and the new colony will still stay connected with the original one. As each new colony makes new queens, the population will grow exponentially.

This is why it may seem as if their populations suddenly exploded. The best way to prevent a population explosion is to survey regularly and catch any new colonies before they can expand. Establishing a quarantine area using a barrier treatment before bringing in new items is essential. Cut back foliage overhanging your property, and always survey a couple of weeks after heavy rains.

LFA workers are tiny, about 1.5 millimeters, pale orange, and slow-moving. There are other ants that resemble LFA that are nearly impossible to tell without a microscope. To confirm LFA on your property collect a sample by surveying as described here.  You can drop off or mail samples at several locations on the Big Island. 

Be cautious when buying potted plants and building materials. LFA also like to hide in things like mulch and gravel. When anything new is brought home, place it in a quarantine area. A quarantine area is a clear spot slightly away from the house where high-risk items can be held before being moved to elsewhere on the property. Use a border treatment (a contact barrier product) to create your quarantine area and make sure all new materials are safely within this area. Place a few chopsticks with a smear of peanut butter around/in the new plants/materials to draw out any LFA. If LFA is found, return the plant or treat it before moving it to another spot on your property. You should always notify the retailer or distributor where you purchased the plant so that they have the opportunity to take care of the problem.

For a list of Big Island nurseries that have agreed to commit to Best Management Practices to control and prevent the spread of LFA, click here.
To keep LFA from wandering in from adjacent properties that are infested, treat your border with a barrier spray or granular. Also, make sure to survey every few months to check if the LFA are managing to move in.

Many people have noticed clouding in their pets’ eyes after continuous contact with LFA. There is no existing research that confirms that LFA do cause blindness in pets, and some vets claim it doesn’t. But there seems to be some kind of link between LFA and pets with cloudy corneas, as this condition is very common in areas with heavy infestations of LFA.

It has been suggested that it is not the ant sting that is the cause, but a bacterial infection that takes place following the puncture of the lens.  There is no conclusive evidence about what impacts, if any, the LFA have on pets at this time.

We recommend that you take precautions to keep your pet food away from ants.  Use a dish of water around your pet’s food bowl with a bit of dish soap in it to prevent ants from getting into the bowl. Remove pet food bowls as soon as your pet has finished eating (don’t leave food sitting in the bowl all day).  LFA are seeking protein, and pet food will be highly attractive to them! 

The best way to control LFA is to use baits. An attractive bait can be laced with an insect growth regulator or a toxicant, which the workers will then bring back to the colony and feed to the queen and developing larvae.  Baiting must be done multiple times, and may not bring instant relief, but will provide the best long-term results in destroying a colony.  There are multiple products you can use to control fire ants on your property, but you will want to make sure to repeat every 4-6 weeks for a minimum of 6 months. A full year of treatment is recommended for best results. Our suggested LFA products calendar can help you design a plan for treatment.

Landscaping is another way to help reduce the amount of LFA on your property. Removing excess debris, dead plant matter, and moss on trees will help to reduce the number of ideal nesting sites. Wherever possible, trim back vegetation so that it does not make contact with your house.  Contact barriers around foundations and entryways can prevent ants from entering your home while you wait for baits to work in your yard.

A comprehensive explanation of treatment can be found here.

Spraying with a contact insecticide like Raid™ or orange oil will only kill the workers that are foraging. That can be great for your short-term comfort, but it won’t solve your ant problem.  Only about 10% of the ants are foraging at a given time, and these are the most expendable ants in the colony so killing them will have very little impact overall. Spraying may reduce the number of workers you see for a few days, but it is not a long-term fix and the ants will return quickly. Baits are best for affecting the heart of the infestation: the queen and her larvae. Foraging ants will return and feed the toxicant to the queen, causing an eventual collapse of the colony. By taking a long-term view, you can reduce your effort and cost over the long run!

It’s okay to use contact pesticides like Raid ™ in your bathroom, kitchen, and where ever the ants make living miserable. Just make sure that using Raid isn’t the only type of control that you are relying on.

Yes, all of the ant control products we recommend are non-restricted use pesticides and have low to no toxic effects in mammals (including humans) and birds. An enormous amount of active product would need to be ingested to have any ill effects.

Some of these products do impact fish and aquatic invertebrates, and so should not be used in or around water systems. Always read the label to make sure that baits are being used safely and properly!

Yes, there are a couple of options.  The insect growth regulator, Tango (methoprene), affects the reproductive system of queens and is labeled for use on fruit trees and around food crops. Tango is a liquid that must be mixed into a bait to be attractive to the ants.

Antixx and Firefighter (spinosad) are two brands of granular baits that can be used on fruit trees.

There are many different species of fire ants in the world, and not all products will work on all species. Too-high concentrations of pesticides can make a bait unattractive to ants.  The Hawai‛i Ant Lab has tested dozens of baits and products to determine which are most effective on the LFA in Hawai‛i, and we recommend using their research-based methods for the best results in your home.

If you are using a recommended product but not seeing results, the answer could lie in several areas.  If the pesticide you’re using is an IGR (Tango) then it will take a few months before you will notice a population drop as the workers must live out their natural life cycle Tango affects the queen’s reproductive system.  This kind of pesticide will not kill workers but will prevent new workers from hatching.

Granular products, such as Siesta and Amdro, have a short shelf life.  Once the bag is opened and sits for some months or even weeks, moisture seeps in and the bait will become unattractive to the ants.  Similarly, if the ground is wet or if it rained shortly after the granules were spread, then the bait will no longer be attractive and the water will degrade the active ingredient in the pesticide, making it useless.

When using an insect growth regulator or IGR such as Tango, the effect on the worker population may not be noticeable for a few months after baiting. But if you stumble upon a nest, you may find some signs of a struggling colony: normally a healthy colony would have lots of eggs and larvae, but when affected with IGR there should be no or very few eggs. Another sign would be the amount and appearance of reproductive ants, winged queens, and males. If there are a lot of reproductives, that can be a sign that the queen is distressed and is trying to make more queens. Healthy queens and males are very dark brown, almost black, but reproductives affected by IGRs will be bi-colored (light head and body and dark abdomen) or the same color as a worker. These off-colored reproductives seem to be sterile.

When using a toxicant there should be a drop in the worker population within a few days after application. The workers that are alive can have trouble functioning depending on what kind of toxicant was used. Some pesticides affect the nervous system, these ants would be very twitchy when moving or become paralyzed and can’t move at all. Other toxicants affect energy production making workers very sluggish.

LFA can’t be exterminated by only treating once.  Multiple treatments are needed to knock down the population to zero-detection levels. It can take a few months to over a year to fully gain control of LFA on your property, depending on how bad your infestation is. Make sure to survey between treatments to monitor your LFA population. When there are no LFA found you can consider switching from a bait to a barrier treatment.

Although there are sometimes infestations in houses, the ants are usually nesting in the yard and are coming into the house to forage for food and water. Start off by using a barrier treatment around your foundation and trimming back any vegetation touching your house or lanai. Be sure to apply product around water lines and electric lines, if possible. The barriers are residual and will kill ants that try to walk over the treated area for a few months.

To get rid of the colony, you must also broadcast some kind of bait in your yard. If you are still noticing a lot of ants inside after about a week, then they may have begun to nest inside. If this is the case, you want to start using bait stations inside the home. A bait station is any container that can hold pesticides. You can purchase ready-to-use products like Raid III or Raid Double Control, or use small plastic containers and fill them with toxicant baits like Amdro and Siesta. You can buy refillable bait stations or use portion cups with small holes in them for the ants to move in and out of.