- We have had Fire Ants in Hawaii since as long as I can remember. They are called red ants and they live in lawns and open spaces. They are nothing new.
- Yes, we have had fire ants in Hawaii for a long time but these are actually a different species. These red ants are also called "Solenopsis geminata" or the Tropical Fire Ant. It can be confusing because both species have a similar common name - Fire Ants - but they are very different. Red Ants are originally from the southern USA and you will find them most often living in nests in lawns and other open spaces. If you look at them closely, the workers can be different sizes, and some have really large heads. Most likely, these will sting you on the feet or lower legs when you accidentally step onto their nest. The sting results in a well-defined welt, like a bee sting.
Red ants are also much larger than Little Fire Ants. Red ants are about half as long as a penny, and Little Fire Ants are about as long as a penny is thick. You are much more likely to be stung on the torso or the arms by Little Fire Ants because they nest in trees as well as on the ground. When you bump or disturb these trees, the ants will fall down and get caught in your clothing. When you feel the sting, often the ants are already gone, and the sting is more like a burning rash that can be as big as your hand, but often smaller.
- They ARE new to Hawaii? - where did they come from?
- These nasty little critters hail from south America and have been spreading slowly throughout the tropics for the last 100 years or so. They are now found in many places such as Israel, the Galapagos, Tahiti, Papua New Guinea, Solomon Islands, Vanuatu, New Caledonia, Guam, Australia and of course Hawai`i.
We are not exactly sure just where "our" Little Fire Ants came from, but genetic comparisons show us that Hawai`i LFA and Florida LFA are very closely related. This kinda suggests that maybe they came to us from Florida somehow.
An interesting journal article on how different LFA populations are related can be downloaded here: http://www.littlefireants.com/Foucaud%202010.pdf
- Where in Hawaii are Little Fire Ants found?
- Little Fire Ants were first recorded on the island of Hawaii (The Big Island) in 1999 by Pat Conant of the Hawaii Department of Agriculture. At first, they seemed to be restricted to the lower Puna area, but in the years since, have spread to just about everywhere between Kalapana and Laupahoehoe and up to around 3000 feet.
In 2000, a small population was found on the Island of Kauai. These ants probably hitch-hiked on some mature coconut palms transported there from the Big Island. The Kauai Invasive Species Committee and other organizations have completed several surveys of Kauai and so far, no other populations have been found there. Right now, the Hawai`i Ant Lab is working with the Kauai Invasive Species Council and Hawai`i Department of Agriculture to eradicate them from Kauai.
All was relatively quiet until October 2009 when they were also discovered on Maui on a single property in Waihee. A multi-agency response team sprang into action and at the moment it looks like the treatment strategy, along with extensive surveys and public outreach have eradicated this species from Maui.
In early 2010, several outbreaks were found in Kona on the west coast of the Big Island. These have increased over the past 2-3 years and they are now scattered throughout the Kailua-Kona district from North Kohala down to Captain Cook. At present, the number of known infested sites is still very low, but this will probably increase.
More recently, in December 2013, LFA were detected on Oahu, Lanai, and once again on Maui. HDOA is currently trying to determine how the ants arrived and what to do in response. It seems that LFA were inadvertantly transported to these location through the transport of hapu'u logs from the Big Island.
- I heard they have been found in Kona and on Maui. How did they get there?
- Its always difficult to work out exactly how pest species get from one place to another unless you happen to be there at the time. But, we can use our knowledge about LFA biology to make educated guesses. First, LFA can spread naturally through a process called "budding". Basically a queen and a few workers can wander off and start a new nest. There are lots of queens in LFA colonies so having one leave the nest is no big deal. However, LFA can't walk too far - they are after all very small and have tiny legs! Walking any further than say, 20 feet would be a major achievement. Swimming across the Pacific from one island to another is highly unlikely!
Little Fire Ants belong to a small group of ant species that scientists like to call "tramp" or "hitch-hiker" ants. What they mean by this is that some ant species, including LFA, often travel from place to place by hitching a ride. Just like a hobo jumps onto a freight train, LFA travel with freight items that are being moved from an infested location to a new location. So, basically, its us humans that move them around, often without knowing it.
We know that LFA like to live in the soil of potted plants, and we also know that there are a lot of potted plants moved from island to island here in Hawaii. So... its very likely that this is how they made their way to Kona and to Maui. Now, HDOA make it as difficult as possible for LFA to do this. Because the quarantine inspectors know how easy it is for LFA to hitch a ride on a potted plant, they inspect all official shipments leaving the Big Island bound for neighbor islands.
Does this mean that if LFA find their way to another island, someone at HDOA did not do their job properly? - ABSOLUTELY NOT! Hawaii is really lucky to have very dedicated HDOA inspectors. First, a lot of people sneak plants from island to island and do not get them inspected by HDOA as they should. This is very difficult to control. Almost every time I am on an inter-island flight, I see at least one person with flowers, foliage, an orchid or a potted plant on the same flight. Its that easy to accidentally move LFA to a new location. The people moving these items would probably not know if those plants had LFA or the risk they are taking by not having their plants inspected. Secondly, no testing method is infallible. While the HDOA inspectors are very careful in their inspections, the test they use could fail from time to time. Third, while we know that LFA often travel on potted plants, they could also travel on a whole other bunch of things so its possible the ants were attached to some non-agricultural item.
- If they are such a problem, why doesn't the government do anything about it. Can't they just eradicate them?
- Well, this is a really complicated question, and the answer is yes... and no. There are a lot of things to consider before attempting to eradicate something, and I'll try to explain this as best as I can. Its a bit complicated, so please bear with me...
The first thing to think about when a new pest is discovered is "will this pest actually be a problem and if so, how big will this problem be"? We have many exotic plants and animals here in Hawaii that arguably do no harm and have very few impacts. It would not make sense to eradicate something unless we knew it was going to cause a lot of damage. When LFA were first discovered in 1999, there was a lot less information available about the likely impacts of LFA but enough had been reported for the authorities to forecast that there would be some. With the benefit of hindsight, we know the impacts will be far more extensive than first estimated.
The next thing that we need to think about is whether there are methods available that have a high likelihood of successfully controlling this pest. This is where things start to get a bit hazy. Little Fire Ants are different from other pest ants. Besides living on the ground like other pest ants, they also have nests in trees. Is this such a big deal? well... YES! Almost all the products available for ant control are granular. They are made to be sprinkled on the ground. The tree-dwelling LFA do not necessarily forage on the ground, so were unaffected by bait granules placed there. When eradication was first attempted, the ants living on the ground were controlled but as soon as treatment stopped, the tree-dwelling nests spread back onto the ground. So, at the time LFA were first found, there was no technically feasible way of controlling them.
This is now changing. Hawaii is virtually the only place in the world where practical applied research is being conducted to develop new ways of controlling LFA. Check out the "research" section of this site for the latest on this.
Costs and benefits
Governments and politicians are reluctant to spend money where they can see no benefit in doing so. This is the way it should be. After all, its OUR money and I for one would not want the government to waste it on some useless project. So an eradication proposal must pass a cost-benefit test (BCR), and these are usually worked out as follows:
1. The total anticipated impact of the new species needs to be worked out in dollar terms. This can be difficult with environmental pests because its difficult to put a value on environmental impacts, but this is what we have economists for and they have ways of doing this. The total costs are discounted to a net present value (NPV) but explaining this is beyond the scope of this answer.
2. The total cost of an eradication program is estimated. This should include all the actual costs worked out through the life of the program, again discounted to NPV.
3. Some expert (usually and expert panel) tries to calculate how likely it is that eradication will be successful. Again this is not so easy but that's what we have scientists for.
4. Now we put all these numbers together as follows: total impacts, divided by total cost and multiplied by the probability of succeeding. So if the total impact of a pest is 1 million dollars, the cost of eradicating it is $100,000 and there is a 50% chance of success, then the BCR would be 5.
Each case is different and each government might set different thresh-holds, but usually an acceptable BCR would be around 15. That means in the case of the example above, eradication might not be a good approach. For LFA on the Big Island, the fact that no feasible control method was available meant that it was not really a good idea to proceed anyway.
However, for Maui and Kauai, the infestations are small, we now have better tools for ant control, and the impacts of not eradicating will be great. These sites pass the BCR test and eradication should be attempted unless more evidence comes to light that changes things.
- How can I tell if I have Little Fire Ants?
- The best way for you to tell if you have LFA is to do a survey of your home and lot. I have prepared a brief outline of how this can be done fairly easily. Just click here to view. If you see some ants around your home and you think they might be LFA, another way is to use some scotch-tape to pick up a few ants, stick this to a piece of paper, and mail them in to HDOA at 16 E. Lanikaula St Hilo 96720. Don't forget to include your contact details. They will identify the ant and contact you.
You can also download the "how to survey for Little Fire Ants" from the drop-down box on our home page.
- I have a microscope - how can I identify them?
- How to identify a little fire ant in Hawaii
we have a basic key to identify whether an ant specimen is a Little Fire Ant or some other species. you can download the key here: http://www.littlefireants.com/Is%20it%20Little%20Fire%20Ant%20%5BMicronesia%5D.pdf
Looking at ants under a microscope for the first time can be an amazing experience. But how do you know what species you are looking at? There are over 50 ant species in Hawaii and 10s of thousands around the globe. You can use this little checklist to work out if your ant is indeed a little fire ant or another ant species present in Hawaii.
It's all about twos...
Little Fire Ants, or Wasmannia auropunctata as seen above have a combination of features unique among Hawaii's ant species.
look for the following features in the order listed:
1. They have two "bumps" between the thorax and abdomen (a petiole and post-petiole).
2. the last 2 segments of the antenna are much bigger than all the others (a 2-segmented antennal club)
3. they have two long spines protruding from the end of the thorax that are long enough to reach to the first "bump" (long propodeal spines)
So if it has the two bumps AND the 2 bigger antenna segments AND the two long spines that reach all the way back to the bumps, then your ant is very probably a little fire ant. But all this can be a bit tricky and even the best entomologists will get a second opinion from someone else. So before anything else, get an expert to check the sample for you to confirm that you are right.
There are some really good websites out there if you would like to learn more about identifying ants in Hawaii and the Pacific region.
First is PIAkey which was developed by Eli Sarnat of UC Davis. Eli is probably the best ant photographer I know and produced the LFA photos above. You can access his key here
Discover Life has a great key to Hawaiian ants here. They also have keys to ants in other countries here.
Remember, if you do not live in Hawaii, or somehow you have an ant that has not previously been recorded here, this key might not work. (be patient, it takes a while to load)
- I have checked my lot and there are none here. What can I do to keep it that way?
- There are some really easy things you can do to keep Little Fire Ants away from your home. Remember, LFA are "hitch-hiker" ants. The way they move from place to place is by hitching a ride with other items. So the first, and most important thing, is to check anything you bring to your home to make sure you are not accidentally bringing LFA as well. The things that are most likely to have LFA traveling with them are potted plants, cuttings, foliage, soil, mulch and landscaping materials. Check these using the chopstick method described earlier.
The second way LFA can enter your property is by natural spread from neighboring properties. This is a much slower process but can also be prevented. The easiest way to manage natural spread is for the whole neighborhood to work together on preventing LFA. Remember, if your neighbor has LFA, eventually you will too. So, get together with your neighbors and develop a neighborhood plan. If everybody is careful about what they bring on to their property, the whole neighborhood will benefit.
Sometimes its too late and there are LFA nearby already, or maybe your neighbors do not live on-site. The best approach then is to survey your property boundaries using the chopstick method on a regular basis. There are barrier chemicals you can apply along the boundary of your property to keep Little Fire Ants at bay. Check the information sheets on managing LFA for a list of suitable chemicals.
- I don't understand what the big deal is. We have lots of ants around the house and in the garden. If any come into the house, I will just spray-em!
- You know, I hear this a lot - but only from people who do not yet have Little Fire Ants. Hawaii has over 50 ant species and almost all of these are not a problem to the average person. Sure, they might come into the house and have some nuisance value there but they are no big problem. I have 2 or 3 ant species in my condo and I don't bother doing anything about them because they don't really annoy me.
LFA are different. First, once they have established themselves around your house, there will be millions, maybe billions of them and when they do get into a house, will over-run it if we let them. Second, they sting people. I get many calls from people at their wit's end. They, their children and pets are getting stung every day. I've even had calls from people being stung while using the rest-room! Third, they will sting your pets or other domestic animals. Life for a dog or a cat in a Fire Ant area can be miserable.
In the end, you're gonna have to work this one out for yourself. Believe me, a lot of people are not worried about LFA when its not in their home, but they seem to quickly change their minds once its there. Once you have LFA, they are not easy to get rid of, so an ounce of prevention is worth a pound of cure!
- I heard that cats, dogs and pigs can go blind if they are stung on their eyes. Is this true?
- Many people believe this is true, and I am one of them. However, its a controversial topic and not everyone agrees. There are certainly some veterinarians and veterinary ophtamologists (eye doctors) who do not. I've developed a separate section on the topic of blindness in pets which you can find here http://www.littlefireants.com/pets.html . If you live in Hawaii, and have a pet with cloudy or damaged corneas, I would like to hear from you. Whether you have LFA or not, please contact me at firstname.lastname@example.org
- Someone told me that the new queens have wings and they can fly to new sites after mating. How far can they fly?
- This is a really interesting question. Most ant species produce new queens and males from time to time, usually when things are going well for the colony. When weather conditions are just right, the queens and the males take to the skies in a "nuptial flight". The queens mate and then look for a good place to land and start a new colony. The males, having done their job, have nowhere to go and eventually die. Once she has landed, the queen will break off her wings and start to lay eggs and a new colony becomes established.
Little Fire Ants do not follow these rules. Scientists think they actually mate in the nest and then stay in the nest along with other queens in an extended family. For people trying to control them, this is both good and bad news. It means that even if a treatment kills some of the queens, often there will be enough queens left over to keep the colony going. On the other hand, it also means that the ants can not spread very far all by themselves. They actually need us to move them to a new location. So just because there are some LFA colonies in an area, does not mean the entire area is doomed. If we can prevent them from moving to new places, the spread will not be that quick.
So how do we do this? Well, whenever you bring something to your home, there is a risk that LFA are sneaking along. If you are careful and check any items that pose a risk, you can prevent the problem before it happens. Items that we know LFA like to hitch-hike on include potted plants, anything with soil attached, produce, plant cuttings, mulch and landscaping material, and landscaping machinery. Always check these items for LFA using the chopstick method.
- What about ant-eaters? Could we get a bunch of them from south America and let them loose here?
- We sure could! Would it work? - probably not…
Importing predators or diseases of an invasive species from its natural range is called "biocontrol". Scientists who work in this field are among the smartest people I know. Many, many biocontrol agents have been used against invasive plants, plant pests, and other invasive species. The trick is to find something that will ONLY attack the pest in question but not affect anything else. To find these natural enemies and do all the testing to make sure it does not cause other impacts is a slow, painstaking process. Often, the biocontrol candidates will happily attack other plants and animals we don't want harmed and these, of course, would not be suitable.
It is easy to make a mistake and end up accidentally introducing biocontrols that are even worse than the original problem. The Indian Mongoose is an example of this. It was introduced to Hawaii in the 1800s to keep rats under control in sugar plantations. Back in those days we did not have the high caliber biocontrol scientists we have today. If we did, the mongoose would never have been released because scientists would have worked out pretty quickly that mongoose will eat just about anything including rare and endangered birds and bird eggs.
I have no idea what would happen to our fragile environment if we released ant eaters and I don't think I want to find out…
- What about other biological controls?
- Some scientists are actively working to find and test natural enemies of the Little Fire Ant. Hawaiian scientist, Dr David Oi is based in the USDA Agricultural Research Service in Gainesville Florida. He has teamed up with Dr Peter Follett of USDA in Hilo and Juan Briano of the USDA South American Biological Control Laboratory who are surveying LFA natural range in the hope of finding new pests or diseases with the potential to control this species. So far, no potential biocontrol candidates have been identified.
you can contact these scientists here:
Dr David Oi http://www.ars.usda.gov/pandp/people/people.htm?personid=11869
Dr Peter Follett http://www.ars.usda.gov/pandp/people/people.htm?personid=10726
Juan Briano http://afrsweb.usda.gov/pandp/people/people.htm?personid=44613
- I have them around my house. What can I do?
- There is a web page with information sheets on how to manage LFA around the home.
You can download the fact sheets from the drop-down menu on our home page
- I don't like to use chemicals. What about natural and organic solutions?
- First of all, a word of caution on "organic" and "home remedies". Just because something is considered "organic" or not artificially made, does not mean it is safe to use, or does not harm the environment! Be careful with anything you use to kill bugs, no matter if it is organic or not. Please treat them all as the dangerous chemicals they are.
If you are an organic farmer and accredited or certified through an organic agency, always check with that agency if they approve of an organic pest control solution before you use it.
There are literally hundreds of "home" remedies and organic methods for controlling ants on the web today. Many of these are just utter nonsense, but some are actually very effective. The Texas A&M University Imported Fire Ant Extension program is a good place to start if you want to see results from actual tests of some of the more popular solutions floating around on the internet. You can access their web page here: http://fireant.tamu.edu/research/results_all.cfm.
Anyway, now to some organic solutions that actually work:
Spinosad is a by-product of the fermentation of naturally occurring organism. there are several commercial bait products available in Hawaii that contain spinosad as the active ingredient. These are manufactured by Dow Agrosciences (http://www.dowagro.com/turf/prod/spinosad.htm) who I think hold the patent. As an active in ant baits, Spinosad tends to be "hit-or-miss" meaning that sometimes it works and sometimes it does not. The reason for this is fairly simple. While Spinosad is an effective insecticide in a variety of applications, it has two drawbacks when used as a bait. For a bait to work as it should, the active ingredient (the bit that is the poison) needs to have a number of specific attributes. One of these is that it should have a delayed effect (not kill things straight away) and it needs to be effective in very small quantities.
When a foraging ant brings a bait home to the colony, she will share it with all her sisters and the queen. If it makes her sick, she will make sure not to share it because she does not want the rest of the colony to get sick as well. Once the bait is shared among the colony, each ant will only have a very small amount of the original dose. Now Spinosad is fast acting and will start to take effect hours after the ant has ingested it. However, if the dose is too small, it will not have any effect at all. So, Spinosad baits act too quickly and do not work well enough in small doses to be a consistently effective bait. Texas A&M University researcher Charles Barr tested this product on Imported Fire Ants and his report is a good place to start your research on this topic. This report can be found here: http://fireant.tamu.edu/research/arr/year/99-03/res_dem_9903/pdf/15_spinosad_cameron_airpark.pdf.
Boron, from which boric acid is derived, is a naturally occurring element. It is a trace element essential to plant life and has a wide and unusual variety of uses ( see http://en.wikipedia.org/wiki/Boron). Among these, is that it can be used as an active ingredient in ant baits. A lot of off-the-shelf ant baits use boric acid either alone or in combination with other actives.
I've tested a bait made with boric acid and the results were not as good as I had hoped. I think this is because boric acid takes a while to accumulate in ants and as a result, they need to be fed the bait over a period of time. I was using it by treating monthly which might not have been often enough. We have a recipe for a boric acid based bait available from the drop-down menu on our home page.
Orange oil (.alpha.-limonene)
Orange oil is a natural insect killer and while I have not tested it against Little Fire Ants directly, see no reason it would not work. When I searched the Hawaii Pesticide Information Retrieval System (HPIRS, go to http://state.ceris.purdue.edu/doc/hi/statehi.html), I found 27 products registered here in Hawaii that contain limonene as the active ingredient. I still think that baits are the best ant control approach because just spraying the ants you see has little effect on the colony. However, if you are looking for a natural insect killer, limonene is worth a go - and it smells nice too.
When visualizing Hawaii, people think of lush palm trees, orchids and rainforests. But much of Hawaii is actually quite arid. Certainly places like Kona are quite dry. Often, the gardens we plant are slightly out of keeping with the natural environment, and many popular garden plants here require lots of artificial irrigation. For Little Fire Ants, these lush gardens are a wonderful place to make home because we are giving them the the two things they really like - moisture and shade.
Xeriscaping is a landscaping approach that minimizes or even eliminates the need for artificial irrigation. It consists largely of choosing water "un-thirsty" plants and landscaping techniques that maximize water retention. By planting xeriscape gardens, you will make your property unattractive to LFA. garden can dramatically change how attractive it is for LFA. Now this approach ain't gonna work if you live in Pahoa where the average rainfall is maybe 200 inches, but if you live in Kailua-Kona for example, it would be a very good approach to minimizing the LFA problem. The Honolulu Board of Water Supply has an excellent web page with links and ideas. Check it out here: http://www.hbws.org/cssweb/display.cfm?sid=1086
So, changing the way you garden, you may well change your risk of having to live with LFA! You will also save heaps on your water bill and be helping to conserve one of Hawaii's most precious resources.
a repository of information about invasive ants