Red Fire Ant

Spring fever has hit and there you are happily  digging away in the soil planting transplants and seeds.  Then you feel that little sting, and then the itch, ouch, they got you.  You know the little critters who who I am talking about, fire ants.

Why Are They Damaging

First of all, let me explain that we have native fire ants as well as the imported fire ants.  The fire ants that we want to get rid of are the imported fire ants.  Imported fire ants in the garden as you may well know can be bad for a number of reasons, first off they are hard to deal with for the reason of their obnoxious stings.  Secondly, they will eat emerging seedlings and seeds. Third, they will herd aphids. They will also kill plants during times of stress.

Knowing More About Them

The imported red fire ant came here in 1930’s from Brazil on cargo ships into the port of Mobile, Alabama. It took about 20 years for the imported fire ants to hit Texas.  We now have four different species in North America of fire ants.

The imported fire ants have two distinct patterns  of colonizing.  There is the single queen colony.  The single queen is very territorial. In a single queen colony there are from 40 to 150 mounds in an acre which equals to about 7 million ants.  Far more disturbing is the multiple queen colony where the queens move freely from one mound to another.  In multiple queen colonies there are about 200 mounds in an acre which is equivalent to about 40 million ants, yikes!  The multiple queen colonies are the mounds which are the hardest to get rid of as well. This is because of the vast number of mounds and area that has to be treated to make sure that you kill the queen so she does not split the mound.  All it takes for her to start another mound is about 6 workers.

The colony is a pretty amazing thing. It contains 100,000 to 500,ooo workers and many hundred winged ants along with the queens.  The queen herself may live 7 years or longer.  The flying queens mate with flying males.  Then the queen lays about 800 eggs per day.

One of the reasons that we have such difficulties getting rid of these creatures is that the queen does not eat her food directly.  It is predigested by a worker ant. Pretty smart isn’t it? So fast acting poisons kill the worker and not the queen.  The object is to have a poison that is a slow poison as to reach the queen.

Controls You will find a lot of different suggestions and I urge you to use caution before you use them.  Let me use an example that you would think is harmless, at first. 3 Gallons of Boiling water is used as a drench. However let me tell you that you are sterilizing your soil.  You have just killed all of your beneficial organisms in your soil that you have been striving for to help you in times of drought and help break down nutrients into available forms. Not only that, the boiling water drench only proves to be 20% effective after 14 days!  So please pay attention and think through things carefully. What you do to the soil impacts it for a long time.     If you have questions about anything please send me an email EdibleSanMarcos

Biorationals Remember this when you are killing the ants, your target is not just the worker ants but the ultimate goal is the queen.

It is the queen that keeps the mounds perpetuating.  With that thought in mind, remember that we are typically dealing with mounds that have multiple queens.  You need to kill all of the mounds in the surrounding area or you will have re-infestation.  So be complete the first time. Reapplications are desired just incase the queen was out flitting about.  Remember they populate fast.

d-limonene – You Probably know this as citrus oil or orange oil and it is used as a drench.  It kills the  ants by disrupting the cells.  Citrex Fire Ant Killer, envirosafelabs containing 78.2% d-limonene has a very high concentrate of d-limonene.  When using a drench you must use enough of it to get to the queen she may be deep inside and is protected by workers.  One thing you must keep in mind when using citrus oils is that it hinders germination of seeds.  So drench the ants in a new bed a few weeks before planting and then water well or used in established areas and lawns.

Spinosad – Saccharopolyspora spinosa -This is a soil microorganism that affects the nervous system and is used in bait form. This is completely harmless to other beneficial organisms and is certified by the Organic Materials Research Institute (OMRI).  I personally use this product and I am very pleased with it.  I switched from a citrus drench 1 year ago and my beds are all but ant free. I still have the invader from time to time, but it is great stuff.

Beneficial Nematodes – Beneficial Nematodes are actually scarps and are really parasites, but they do not effect humans.  They seek out heir host by infrared detection and penetrate them.  They carry a bacteria that is deadly to the host organism and within 48 hours the host usually dies. You need to use a combination of two species of nematodes for the application to be effective against fire ants. The species you want to look for are Steinernema carpocapsae and Heterorhabditis.  They are available commercially in many places.  You want to make sure that they are fresh and that you handle them accordingly.  You need to apply them the day you get them or the following day as they are fragile.  Nematodes are completely safe and will kill other pests in in your garden.

Beauveria bassiana – This is a fungi from the Fungi Imperfecti class that was believed to have come here with the ant itself and is it’s natural enemy. When the fungi attaches itself to the ant  the spores grow on and into the body of the ant and the ant dies. This is a natural and safe treatment as it is just a natural fungi.

Pyrethrins – work on the nerve system and are used as both mound treatments and surface sprays. Many products are combined with Diatomaceous Earth. They break down very quickly in the environment, however they are harmful to bees and beneficial insects.

Rotenone – due to it’s nature it is slow acting by affecting respiratory tissues, nerves and muscles.  They break down very quickly in the environment however they are harmful to bees and beneficial insects.  Rotenone is generally used as a mound drench.

Avermectins – It is a bait that is made from a soil fungus that is used in two ways.  First as a mound treatment where it kills worker ants and the colonies and secondly as a broadcast treatment where it works as an insect growth regulator, preventing the queen from producing viable eggs.  The trade names are Ascend®, Clinch ®, and Varsity®.

Diatomaceous Earth – Ground up fossilized one celled diatoms that pierce the exoskeleton of many pests. It is used as a drench only in a powdered form.

Derivatives of pyrethrins -allethrin, resmethrin, sumithrin, tetramethrin– Just like pyrethrin these affect the nerve cell membranes and have a quick kill.  These are called contact insecticides and are used as mound drenches, aerosol injections, and surface sprays. They break down very quickly in the environment, however they are harmful to bees and beneficial insects.

Solar Powered Ant TrapHeitman Labs This is a solar powered ant trap, you then drown the ants in soapy water.

Mound Injection Tool – Earthfire – This is a serious application not for the faint of heart.  It is EPA approved. It is a propane gun, that you insert into the mound, and it shoots the heated active ingredient, Resmethrin, and fumigates the entire mound. Poof! Gone.

Natural Enemies

The natural enemy that makes the biggest impact is in fact the armadillo in TX. 50% of the his diet is ants and he is non selective.  So don’t chase them out of your yard! The native fire ants are also a threat to imported ants. Phorid flies land on the head of the ants and pupate there. Then when they emerge the head comes off. They have been released in our area for studies by UT.


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