Allegheny mound ant

(Formica exsectoides)

               
Conservation Status

IUCN Red List

not listed

Allegheny mound ant

 

NatureServe

NNR - Unranked

Minnesota

not listed

Occurrence

Common in the east, uncommon in Minnesota.

Flight/Season

 

Habitat

Open shrublands and woodlands, woodland edges and openings

Size

Worker: to 5 16 (4.5 to 7.5 mm)

Male: 5 16 to (8 to 9 mm)

Queen: 5 16 to (8 to 9 mm)

          Photo by Dan W. Andree
 
Identification

Allegheny mound ant is a large, bicolored, mound-building ant. It is found in the United States from Maine to Georgia, west to Colorado and New Mexico, and in adjacent Canadian Provinces. Within that range, it occurs only sporadically in the south, in the west, and in Canada. It is most common from New England to Illinois. It is uncommon in Minnesota.

Workers are to 5 16 (4.5 to 7.5 mm) long, black, and somewhat shiny. Winged males and queens are about the same size, 5 16 to (8 to 9 mm) long. The body is divided into four easily distinguishable sections: the head; the first body section behind the head (mesosoma); the narrow, waist-like section (petiole); and the inflated rear section (gaster). The head and mesosoma are yellowish-red, light red, or medium red. The gaster is dark. The body is virtually hairless. Only the back of the gaster has erect hairs.

The head is red and broadly rounded in outline. The rear margin is distinctly concave, an important distinguishing feature of this species. There are two large compound eyes on the sides of the head and three simple eyes (ocelli) in a triangle on the top of the head. The jaws (mandibles) have at least seven teeth. The antennae have twelve segments. There is a hardened plate (clypeus) on the face above the mandibles. The clypeus is not notched or concave on its outer (anterior) margin. The antennae are inserted on the face well above the clypeus.

The mesosoma is lumpy, not smoothly convex. It is covered with three exoskeletal plates, each forming a distinct bump. The first plate (pronotum) and second plate (mesonotum) cover the thorax. Together they are referred to as the promesonotum. The third plate (propodeum) covers the first segment of the abdomen which is fused to the thorax. When viewed from the side, the propodeum is distinctly lower than the level of the promesonotum. The petiole has a single raised bump (node). The gaster is bulbous and very dark brown, looking almost – but not – black. At the end of the gaster there is a tiny but distinctive nozzle (acidopore). The acidopore is fringed with hairs.

 
Similar
Species

Ulke’s ant (Formica ulkei) head is dark on top, red below. The mesosoma is red, the gaster black. There are many erect hairs on the body.

 
Larval Food

Plant sap and flower nectar

 
Adult Food

Mostly honeydew of aphids, scale insects, and tree hoppers, but they also prey on various insects.

 
Life Cycle

Allegheny mound ants build very large dome-shaped mounds (nests) that can be up to one meter high and two meters in diameter. The mounds are covered in soil, not thatch. They are often clustered. Adjacent mounds are often interconnected and they share foraging trails. Each mound can have up to twelve queens.

 
Behavior

Workers are aggressive and will bite if their mound is disturbed. Using their acidopore, they inject formic acid into small trees and shrubs near their colony, killing those plants.

They invade the nests of, and enslave, colonies of somewhat silky mound ant (Formica subsericea) and other ants in the fusca group of Formica ants.

 
Distribution Distribution Map  

Sources: 24, 27, 29, 30, 80.

 
Comments

 

 
Taxonomy

Order:

Hymenoptera (ants, bees, wasps, and sawflies)

 

Suborder:

Apocrita (wasps, ants and bees)

 

No Rank:

Aculeata (ants, bees and stinging wasps)

 

Superfamily:

Formicoidea (ants)

 

Family:

Formicidae (ants)

 

Subfamily:

Formicinae

 

Tribe:

Formicini

 
Synonyms

Formica exsectoides exsectoides

Formica exsectoides hesperia

 
Common
Names

Allegheny mound ant

 

 

 

 

 

 

 

Glossary

Clypeus

On insects, a hardened plate on the face above the upper lip (labrum).

 

Gaster

The bulbous part of the abdomen of ants, bees, and wasps. In ants it usually begins at segment three.

 

Mesosoma

In Hymenoptera: the front part of the body, consisting of all three segments of the thorax and the first segment of the abdomen, to which the wings are attached.

 

 

 

 

 

       
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Dan W. Andree
       

Ant Colony.....

Not sure what kind of ants they are but they were in a thick clump along the area I was walking. I do not think I have ever seen this kind of ant. Maybe fire ants or some other kind I haven’t seen around the yard or in town.

I think they were carrying some larvae around. I did film them too. They did not come near me they just seemed so busy doing whatever they were doing. I often looked down to be sure none were crawling on me though I did remain 3-5 feet away. It was chilly out so I think maybe they didn’t notice me and had to get whatever they were doing done. I have never seen so many ants in a small area crawling on top each other etc. Sending a large resolution since they are small and maybe that will help identify them better or maybe you will know what they are doing.

  Allegheny mound ant   Allegheny mound ant
       
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Other Videos
 
  alleghenyMoundAnt.MOV
MsPangolin
 
   
 
About

Published on May 16, 2011

Tired of lions ? Consider Formica exsectoides, aka the Allegheny Mound ant.

   
       
  Ant riot!!!
xiang73
 
   
 
About

Published on Jun 8, 2011

Formica Exsectoides - Allegheny mound ant.

   
       
  Alleghaney mound ants
Bug of the Week
 
   
 
About

Published on Jul 18, 2016

On the surface of a large Alleghany mound ant nest workers busily reposition grains of soil, while on a nearby foraging trail some workers return to the colony with food as others pass to pick up their loads.

   
       
  allegheny mound ant foraging trail
Roberta Gibson
 
   
 
About

Published on Aug 6, 2017

Allegheny mound ants on a foraging trail

   
       
       
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Dan W. Andree
9/7/2019

Location: Lee WPA, rural Norman Co. MN

Not sure what kind of ants they are but they were in a thick clump along the area I was walking. I do not think I have ever seen this kind of ant. Maybe fire ants or some other kind I haven’t seen around the yard or in town. I think they were carrying some larvae around. I did film them too. They did not come near me they just seemed so busy doing whatever they were doing. I often looked down to be sure none were crawling on me though I did remain 3-5 feet away. It was chilly out so I think maybe they didn’t notice me and had to get whatever they were doing done. I have never seen so many ants in a small area crawling on top each other etc. Sending a large resolution since they are small and maybe that will help identify them better or maybe you will know what they are doing.

Allegheny mound ant


     
     
 
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Created: 9/24/2019

Last Updated:

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