somewhat silky mound ant

(Formica subsericea)

Conservation Status
somewhat silky mound ant
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Somewhat silky mound ant is very common in the United States east of the Great Plains, with only spotty records in the west. According to an entomologist at Missouri Botanical Garden, it is “By a considerable margin the most abundant and widely distributed black Formica east of the Rocky Mountains.” It is uncommon in most of Minnesota, though it is reported as common at Cedar Creek Ecosystem Science Reserve in Anoka County. It is found in woodlands and in suburban areas.

Workers are to 5 16 (4 to 8 mm) long, black, and somewhat shiny. Winged males and queens are about the same size, 3 16 to ½ (5 to 13 mm) long.

The first body segment behind the head (mesosoma) has two distinct elevated areas (bumps). It is covered with three exoskeletal plates, the pronotum and mesonotum covering the thorax, and the propodeum covering the first segment of the abdomen that is fused to the thorax. The pronotum and and mesonotum form one smooth convex bump, the propodeum a second convex bump. The second abdominal segment (petiole) is narrow and waist-like, and has a single raised bump (node). The remainder of the abdomen (gaster) is bulbous. The head, mesosoma, legs, and first three segments of the gaster are covered with silvery appressed hairs. The fourth segment of the gaster is bare or almost bare. There are single rows of erect golden hairs at the end of each segment. On the first segment there are also usually 10 to 25, sometimes just 1 to 3, erect hairs not including the row at the end. Those are each shorter than or equal to the distance between them.

The head is broadly rounded in outline. The rear margin is rounded, not distinctly concave. The eyes are large. The facial plate above the mouth (clypeus) is not notched. The finger-like sensory mouth part (maxillary palp) is long and has six segments. The basal segment of each antennae (scape) is very long, longer than the length of the head.

 
     
 

Size

 
 

Worker: to 5 16 (4 to 8 mm)

Male: 3 16 to ½ (5 to 13 mm)

Queen: 3 16 to ½ (5 to 13 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Woodlands, suburbs

 
     
 
Biology
 
 

Season

 
 

Present from spring thaw to first frost of fall. Nuptial flight in July or August.

 
     
 

Behavior

 
 

Somewhat silky mound ants are often found as slaves in colonies of Amazon ants (Polyergus spp.).

 
     
 

Life Cycle

 
 

Nests are variable in size.

 
     
 

Larva Food

 
 

 

 
     
 

Adult Food

 
 

Aphid honeydew, soft-bodied insects, and seed husks.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 27, 29, 30, 80.

 
  10/26/2020      
         
 

Occurrence

 
 

Very common in eastern United States; uncommon in Minnesota

 
         
 
Taxonomy
 
 

Order

Hymenoptera (ants, bees, wasps, and sawflies)  
 

Suborder

Apocrita (wasps, ants and bees)  
 

Infraorder

Aculeata (ants, bees and stinging wasps)  
 

Superfamily

Formicoidea (ants)  
 

Family

Formicidae (ants)  
 

Subfamily

Formicinae  
 

Tribe

Formicini  
 

Genus

Formica  
  No Rank Fusca Group  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

black field ant

silky field ant

somewhat silky mound ant

 
       

 

 

 

 

 

Glossary

Gaster

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

 

Palp

Short for pedipalp. A segmented, finger-like process of an arthropod; one is attached to each maxilla and two are attached to the labium. They function as sense organs in spiders and insects, and as weapons in scorpions. Plural: palpi.

 

Scape

On plants: An erect, leafless stalk growing from the rootstock and supporting a flower or a flower cluster. On insects: The basal segment of the antenna.

 

 

 

 

 

 
 
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Alfredo Colon

 
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    somewhat silky mound ant   somewhat silky mound ant  
           
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    somewhat silky mound ant   somewhat silky mound ant  
           
    somewhat silky mound ant   somewhat silky mound ant  
           
    somewhat silky mound ant   somewhat silky mound ant  
           
    somewhat silky mound ant   somewhat silky mound ant  
           
    somewhat silky mound ant   somewhat silky mound ant  
           
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  Alfredo Colon
8/13/2019

Location: Woodbury, Minnesota

somewhat silky mound ant  
  Alfredo Colon
8/12/2019

Location: Woodbury, Minnesota

somewhat silky mound ant  
  Alfredo Colon
8/8/2019

Location: Woodbury, Minnesota

somewhat silky mound ant  
  Alfredo Colon
8/2/2019

Location: Woodbury, Minnesota

somewhat silky mound ant  
  Alfredo Colon
June 2018

Location: Woodbury, Minnesota

somewhat silky mound ant  
           
 
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Created: 1/11/2019

Last Updated:

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