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Pain and Anguish: Identification of the Campus Stinging Ants
By Bill Willis and Bill Steinmetz
June 20, 2018
Story Highlights
The invasive fire ant is native to South America while the pavement ant is native to Europe
Fire and pavement ants sting when agitated or disturbed, fire ants being more active and aggressive
The colony shape and the ant anatomy help distinguish between these two types of ants
Can you tell if I'm one of the good guys?
Imported fire ants and pavement ants are now part of the North Carolina landscape. The spread of these ants presents a safety concern to humans, livestock, native wildlife and an economic loss because of their aggressive nature. Both ants enter dwellings in search of food and can cause personal harm and possible structural damage.
The over 1000 ant species in North America and 178 species in North Carolina most serve an important role in the environment. They do help with soil aeration, insect control, and landscape cleanup. Only a few of the North Carolina species come into direct conflict with humans. The imported fire ants and the pavement ants are among invasive species that do, so it’s good to be able to identify them.
What Are Some of the Distinguishing Differences That Help Tell These Two Species Apart?
Imported Fire Ant Photo courtesy of Pinterest TexasMonthly
Fire Ant
Solenopsis invicta (Buren)
Anatomy
Considered a medium sized ant (casts differ)
1/16 - 1/5 inch long
Reddish brown in color, dark abdomen
Stinger is prominent
Two nodes between thorax and abdomen
No spines at end thorax
No distinctive grooves on head and thorax
Head narrower than the abdomen
Antenna with 2 clubs and 10 segments
Well-formed ant mounds on NIEHS campus Photo courtesy of Bill Willis
Habits
Bite and sting when threatened
Active and aggressive, will battle
Omnivorous (live or carrion)
Found coast to coast, up to Virginia (cold limits)
Nest in ground, mound raised multiple entrances
Open ground or low grass
Underground tunnels
250,000 ants in colony
500,000 maximum reported
Multiple queens
Pavement Ant Photo courtesy of Pinterest Arizona
Pavement Ant
Tetramorium caespitum (Linnaeus)
Anatomy
Considered a small ant
1/10 – 1/6 inch long
Dark brown to black, pale colored legs
Stinger not prominent
Two nodes between thorax and abdomen
Thorax spines, and stiff hairs over body
Distinctive grooves on head and thorax
Head wider than abdomen width
Antenna with three clubs, 12 segments
Pavement ant mounts on a gravel path Photo courtesy of Bill Willis
Habits
Sting only when threatened
Rarely aggressive, territorial, will battle
Sweets, honeydew
Found in all 50 states
Mound volcano-like entrance
Under sidewalk, pavement, foundations, rocks
Distinctive foraging trails
3000 to 5000 ants in colony
30,000 maximum reported
Multiple queens possible, usually only one
Stay tuned for a future article that will explore ways to control these biting and stinging critters.
Editors Note: The author acknowledges the presence of native fire ants in the United States, that include: Southern, Tropical, Desert and Little fire ants. The black fire ants also live in a few southern states where it causes crop and agriculture damage by eating plant stems and fruit as well as by protecting aphid that suck out plant juices. All these are capable of stinging but don’t pose a problem in North Carolina.