Red imported fire ants

 

Red imported fire ants are a non-native species that originate from South America.  They were accidentally introduced in Mobile, AL in the 1930’s.  Ships used soil as ballast as a method of stabilization, and it’s thought that fire ants were unknowingly in ballast removed from South American ships.  From Mobile, fire ants spread in the southern U.S., entering Texas in the 1950’s.

Fire ants bite and sting and can sting multiple times.  The stinger, located on the tip of the abdomen, injects venom that can cause pain, burning and/ or redness. The sting area develops into a small pustule within a few days.  The pustule may itch and is sterile, unless it is broken open by scratching, which then may lead to secondary infection. Some people may develop an allergic reaction to fire ant stings/ venom. Allergic reactions can vary in severity with some causing life-threatening anaphylaxis. If you have concerns over non-typical reactions after being stung by fire ants, seek medical attention.

Ways to manage fire ants can be broken into two basic categories- broadcast treatments and individual mound treatments.  Individual mound treatments treat one mound at a time and are labor intensive, requiring you to search and find every fire ant mound for treatment and can result in more pesticide being applied to the environment.  Broadcast treatments spread product (granular or bait) over a large area using specialized equipment.

With any pesticide treatment, read and follow all label instructions.  Make sure to water in the pesticide if the label instructs you to do so.  Failure to water in chemicals when recommended by the label does an inadequate job of killing the ants.  Baits should not be watered in or used before a rainfall event; baits will not be picked up by ants if they get wet.

Texas leafcutting ants

Texas leafcutting ants, Atta texana, are a native Texas species that create large, extensive colonies. Colonies often have multiple volcano or crater-shaped mounds with a central opening clustered in a single area.  Leafcutting ant mounds (see image) can be mistaken for fire ant mounds, but fire ant mounds do NOT have a centralized opening.

Workers are the most commonly seen leafcutting ants, but in spring it is possible to see reproductives, or swarmers.  Workers (see image) are medium to large ants, reddish-brown in color and have three pairs of spines on the thorax and one pair of spines on the back of the head.  Workers come in various sizes but can be up to ½ an inch long.  Reproductives look similar to worker ants but are much larger in size, with females being over an inch long. Mated queens have a special area within their mouth to carry fungal spores used to create a fungus garden in their newly founded nest.

Leafcutting ants typically forage when temperatures are cooler.  During this time of year, that can have them out in the middle of the day, but during the summer they tend to forage at night or in the morning. Workers remove leaves and buds from plants in the landscape; they then chew the plant material and get some nutrition from sap, but mainly place chewed leaves in an underground garden within their colony.  The chewed plant material is a base to grow fungus which the ants eat. Leafcutting ants tend a particular species of fungus and weed out any other fungus from their garden.

Colonies (see image) may exist for years and can exceed over two million ants.  It is not unusual for a single colony to cover an acre of land.  Colonies are usually found in well drained, sandy or loamy soils and are more common in Central to East Texas than other parts of the state.

Unfortunately, leafcutting ants can be difficult to manage, and almost impossible to eradicate completely.  Prized plants can be temporarily protected by using spray adhesives around the base of the plant, but adhesives need to be refreshed often when dirt and/or debris accumulates.  Temporary protection can also be provided to prized plants by utilizing contact insecticidal sprays or dusts labeled for “ants”.  These insecticidal products can also be used along foraging trails and openings where the ants go into the ground.  If mounds are present, Amdro Ant Block, which is the only product labeled for use against leafcutting ants, can be broadcast with a hand-held spreader around the mound area.  Do not use ant bait and residual dusts and/or sprays in the same area since pesticidal dusts and sprays will contaminate bait and cause the ants not to pick it up.

When managing leafcutting ants, set expectations at managing, not eradicating.  Often when you treat, you’ll knock back a portion of the worker population, but the colony will remain.

This work is supported by the USDA-NIFA Extension Implementation Program, project award no. 2024-70006-43508, from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.

Ant or termite swarmer?

With the warm(ish) temperatures- I know, it's been all over the thermometer in Central Texas the past few weeks!- and the rain, both ant and termite swarmers have been spotted around town.  So if these insects emerge around the same time, do you know how to tell the difference?

Ants will have the following:

1. Antennae are elbowed
2. Front wings are larger than hind wings
3. No wing scale (they chew off their wings after the land on the ground)
4. Middle part of the body is narrowed/ constricted

Termites will have the following:

1. Antennae are straight
2. Wings are of equal size & shape
3. If wings are shed, a wing scale (the base part that attaches wings to thorax) is left behind
4. Middle part of the body is not narrowed/ constricted

Argentine Ants

I've been getting samples submitted where people suspect that they have Tawny crazy ants infesting their property.  They report light brown ants in dense populations getting into everything.  Once the samples are submitted, I discover that they are Argentine ants.  So why are people mistaking Argentines for Tawnies?  Well to the inexperienced they can look very similar especially when you don't have a good hand lens or microscope to look for hairs on the body.  Also, both of them can have high population numbers and supercolonies.

Argentine ants are light brown to brown in color and all workers are the same size (about 1/8").  The legs are not overly long like with crazy ants, but this can be difficult to determine unless you tend to look at ants a lot.  If you have a hand lens, you can check out the tip of the abdomen first.  Argentine ants do not have a sting and they don't have a circle of hairs at the tip of the abdomen.  Next, look at the thorax of the ant.  If the thorax does not have hairs, then it's most likely going to be an Argentine ant (Crazy ants have long paired hairs on the thorax). 

Argentine ants in the Urban Lab at TAMU.

The other ant that breaks out in the same couplet  (in a dichotomous key, characteristics are paired so that you work your way through the key by choosing one of the couplets that has similar characters to your specimen and the paired characters that you choose from is a couplet) as Argentine ants are the Cheese ants.  If you have multiple ants, then determination of cheese ants is very simple....smash one of the ants and smell your finger.  You're thinking I'm crazy now...right?  I'm not (my mother had me tested...actually that was Sheldon, not me.  If my mom had me tested she did not tell me the results which could be good or bad).  Anyway, I digress.....have you smelled your finger yet?  If you have cheese ants then your finger will smell like blue cheese.  I swear! 

So, if you have small to medium brown ants trailing around that worry you, you should:
1. Squish some and smell your finger.  If you have a blue cheese smell, then you have Cheese ants.
2.  Look at the thorax with a good hand lens or microscope.  If you have paired hairs on the thorax, then you have Crazy ants.  If there are no hairs then you have Argentine ants.

So here is my disclaimer.  This method is really simplified and I may possibly get lynched by entomologists and even more so by myrmecologists (ant specialists) for simplifying it so much.  Ant identification involves looking at nodes, counting antennal segments, looking at hairs on specific parts of the body amongst other things, so this is a generalization but may help you out.  It is very important to identify the ant that you are trying to manage before you try to control them.  If you cannot do this or are unsure of your identification, then send it to me and I am happy to look at it for you.

All Bugs Good and Bad Webinar Information

The webinar from August is now posted for you to watch at your convenience.  It is "Minimize Mosquito Problems" by Molly Keck.  You can find that here (click watch recording in the top right corner):
https://learn.extension.org/events/1373#.U_eT1aPFpCw
The next webinar will be held on September 5, 2014 at 1PM CDT.  That webinar will be "Kudzu Bug Takes Over the Southeastern U.S./ Brown Marmorated Stink Bug--All Bad" and will be given by Dr. Michael Towes and Dr. Tracy Leskey.  You can find more information and a way to link to the webinar here:
https://learn.extension.org/events/1379#.U_eTpaPFpCw

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