Ant identification: April 2010 Archives

I live in the Northern USA and wanted to know if Fire Ants will ever be a pest in my yard?


The Red Imported Fire ant, Solenopsis invicta, is an introduced pest in the United States from South America. There are also native fire ants (species of the genus Solenopsis) found in many parts of the world, including the United States. Although the Red Imported Fire ant is an introduced pest in many parts of the United States, Australia, and some islands, it is unlikely you will ever have the invasive Red Imported Fire ant in the northern US since they are not able to survive long winters with hard freezes. Red Imported Fire ants are considered "hot climate specialists". This means they are unlikely to survive in your North Dakota yard, but may still be able to survive in places with temperature controlled environments like greenhouses. This species has even made the list of "100 of the World's Worst invaders": http://www.issg.org/database/species/search.asp?st=100ss

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Solenopsis invicta - Red Imported Fire ant. Photo by Alex Wild (www.alexanderwild.com).


Where in the US are Red Imported Fire ants found?

The Red Imported Fire ant is thought to have been first introduced in the US in the late 1930's in the port of Mobile, Alabama. They are considered a serious problem due to many factors that include their ability to spread rather rapidly, their painful sting, aggressive behavior, and damage to some agricultural crops and livestock. In the United States fire ants have spread from Alabama across the southern US and into isolated areas of California, which has resulted in quarantines of movement of some products like soil and plants to help stop the spread of these invasive ants. Although we are not certain how much further north and west they will spread, we do know that they will not be able to survive outside in areas with long, cold winters.


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Distribution of Red Imported Fire ants in USA. Map from: http://www.invasivespeciesinfo.gov/animals/rifa.shtml


Why are they called Fire ants?

Well if you have ever been stung by a Fire ant you can answer this question. Fire ants get their common name from the fact that when they sting you it feels as though you have been touched by a red-hot flame. These ants bite onto you (or other enemies, intruders or prey) with their jaws and then inject a dose of venom with the sting on the rear end of their body. Their sting is not only painful, but for some people this can be a real problem since it can result in anaphylactic shock or even death in very extreme cases. Also most people develop an itchy, puss filled bump after being stung.

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Fire ant stings. Photo from: http://www.ars.usda.gov/fireant/project.htm

How can I identify a Fire ant?

Telling fire ants apart from other ants can be difficult since they look like most ordinary red/brown ants, although AntWeb and a microscope will help. Two of the key signs are their behavior (they are very aggressive and sting readily) and mound-shaped nests. Each of these mounds can contain up to 300,000 individual ants.

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Fire ant mound. Photo by Alex Wild (www.alexanderwild.com).

Although this species is considered an invasive pest in some areas like the United States and Australia, it is important to keep in mind that they are not all bad. In their native range of South America it is one of many important ants in the ecosystem. For more information on the Red Imported Fire Ant, check out this webpage which contains many informative links:
http://www.invasivespeciesinfo.gov/animals/rifa.shtml

- Corrie Moreau & the AntAsk Team

I'm doing a project for school, and I'm trying to find out how many different kinds of ants there are. I checked in a few different places, but I keep getting different numbers. What's the real number?
-Ruchika, Mumbai, India


That's a great question, Ruchika, and we're still trying to figure out the answer! Because scientists discover new ant species every year, the number of species is always going up. So far scientists have given formal scientific names to about 14,000 ant species and subspecies, but we know there are many, many more ants out there that have yet to be discovered and given formal scientific names. Since the AntWeb species database is closely maintained by some of the leading ant taxonomists (scientists who name and describe species), it is one of the best places to look for how many species are currently recognized.

There are two main places you can look on AntWeb to find the latest statistics on how many species there are: on the AntWeb homepage and on the AntWeb "The World Ants" page. As of April 2010, the number of species given is 14,095.

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Although there have been over 14,000 formal scientific names given to ants, no one really knows exactly how many species of ants are alive today. New species, especially in tropical rain forests around the world, are discovered every year. Even in the United States there are new species of ants that have yet to be given formal names. As you look around AntWeb there is evidence for the existence of new species waiting to be described. Often, when you look at a regional list of ant species in the Bioregions pulldown on AntWeb, there are many entries with a genus and species name, but there are also entries with a genus name, and then some short code of letters and numbers, like Solenopsis nz01, or Adelomyrmex jtl007. The codes (usually taken from the taxonomist's initials, or an abbreviation for were the specimen was collected) sometimes mean that the curators of those regional lists think those specimens belong to a species new to science.

People often think that there are only red and black ants, but as you have found, there are many more kinds than that. That's part of what makes studying ants so exciting! Not only are there many different kinds of ants, they come in many sizes, shapes and colors. We encourage you to look around AntWeb at the amazing diversity of these fascinating insects.

- Jesse Czekanski-Moir & the AntAsk Team

Dear Eric,

Thanks for your question - this is a common one that many people might be curious about.  Ants and termites share a number of remarkable similarities in their colonial lifestyle, but there are three key physical differences to tell them apart.

  1. Ants have elbowed antennae, where the first segment is much longer than the segments that follow. By contrast, termites have straight antennae that appear like a string of tiny beads.
  2. Ants also have a characteristically constricted "waist" while termites do not. In termites the body segments are much more broadly attached.
  3. Forewings of reproductive (queen and male) ants are larger than hindwings, while reproductive termites have two sets of wings of similar size and shape, often twice the length of their body.
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(http://www.daff.gov.au/aqis/avm/vessels/fact-sheets/termite)


Both ants and termites live in colonies or nests where one or relatively few individuals reproduce while non-reproductive individuals cooperate to care for brood, maintain the nest, and defend the colony. These features - reproductive division of labor (only the queens lay eggs), overlapping generations (you have all ages in the nest), and cooperative brood care (all individuals care for the young, not just the queens) - are hallmarks of eusociality, a condition achieved in relatively few insects. Although all ants and termites are eusocial, both groups vary broadly in colony size and social sophistication. Mature colonies of certain species may contain fewer than 100 physically similar individuals, while colony membership can swell to several million individuals in other ant and termite species and include several morphologically and behaviorally specialized castes (e.g. soldiers, several classes of workers).

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Camponotus sansabaenus - worker ants vary in size, color, and body proportion. Photo by Alex Wild (www.alexanderwild.com).


Despite these similarities, ants and termites are not very closely related and developed social behavior independently. As such, there are several key distinctions between ants and termites in the details of social life. In colonies of ants, bees, and wasps, virtually all nestmates are sisters, and the nest is typically headed by one or a limited number of queens. Males are produced only at certain times of the year and serve as short-lived mobile reproductive machines, emerging from the nest to mate with virgin queens and then quickly die. Once mated, a queen founds her colony (sometimes with the aid of workers from her natal nest) and uses sperm stored from her first mating event for the rest of her life. By contrast, termite colonies are founded by a king and queen, which meet in a mating swarm and together select a nest site. The pair is monogamous and must periodically re-mate. Unlike the female-only colonies of ants, males are an integral part of a termite colony's workforce and may be workers, soldiers, or both, depending on the termite species.

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Prorhinotermes inopinatus worker and soldier termites in a rotting log.  Photo by Alex Wild (www.alexanderwild.com).


Complex social organization and large colony size has facilitated the success of many ants and termites, which are critical to ecosystem functioning around the world. Ants and termites are essential bioturbators, overturning and enriching soil by excavating tunnels and amassing nutrient-rich resources at nest sites. Ants also play a host of other roles, serving as predators, prey, and seed dispersers to a variety of organisms, while termites recycle otherwise inaccessible nutrients into the ecosystem by decomposing wood with the aid of gut bacteria or protists. Perhaps because of their ecological success, several ant and termite species are familiar household pests, including carpenter ants (Camponotus) and the Formosan subterranean termite (Coptotermes formosanus).

Whether ant or termite, social insects are a fascinating and important part of global biodiversity.

- Tim O'Connor & the AntAsk team

Dear Mary, this is a great question!

Almost every ant you ever encounter is female! In ants, all individuals that perform work for the colony are females. We usually refer to these ants as "workers", but in some ant colonies that have different roles, specific workers are sometimes referred to as "soldiers" or "nurses". Regardless of the name and task of these ants, they are all female. The sexuals or reproductives in ants are called "alates". Females are called queens or gynes, while males are usually just called males. In the case of male alates, their only function is to reproduce. They usually stay in their home colony until they are fully developed and then they fly away to mate. Almost all male and female alates have wings and often they mate in the air on nuptial flights. Males usually only mate once and then they die--having fulfilled their purpose in life. The female queens, on contrary, try to found a new colony after mating with one or several males. They then shed their wings and find a suitable place to start a new nest.

When you see a winged individual, you can recognize males based on their small head and their long antennae. Males usually have more antennal segments than the females. When you see a wingless individual, queens have already removed their wings are larger in size than the workers, have a wider thorax due to the wing muscles and they show wing scars. Ant colonies or nests are almost entirely made up of females. So the next time you see an ant without wings, you will know it is female.

 

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In this picture, we see (A) a male, (B) a winged young queen, (C) queen after shedding her wings, and (D) a worker of the acacia-ant Pseudomyrmex peperi. The male has long antennae and a small head with large eyes. The winged young queen can be recognized on base of her wings and at the same time shorter antennae. The wingless queen has no wings, but you can still see wing scares. The gaster (rear end) of most egg-laying queens becomes distended with eggs, a state that is called "physogastric". The queen is larger in size than the workers. The worker has short antennae, no wings and no wing scars.


- Steffi Kautz & the AntAsk Team

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