Argentine Ant
( Linepithema humile )


2014-0411-SP175006-HYM00148-Linepithema_humile[1619h18s,F,C,beneath-log]{EXD}-G.jpg

PHOTO COMMENT
Experts believe that this ant is so successful because all individuals originated from the same colony introduced to New Orleans. So, there is no inter-colonial aggression or competition. Colonies have multiple queens, reproduce in great numbers, nest in diverse habitats, and eat a wide variety of foods.
These ants arrived in the United States via coffee shipments from Brazil in 1865. Today, they are California?s #1 pest in homes and agriculture. These ants tend aphids for honeydew rewards. Aphids are protected from predators. A single colonies may have many queens. Colonies and workers are tolerant of outsiders and a worker may switch colonies many times in its life. These ants prefer sweets and will move into households when aphid honeydew sources outside are swept away by rain.

IDENTIFICATION
Identification:Linepithema humile
(Mayr, 1868)
Common Name:Argentine Ant
Life Stage:(C) colony

PHYLOGENY

Phylum:Arthropoda
Class:Insecta
Superorder:Holometabola
Order:Hymenoptera
Suborder:Apocrita
Family:Formicidae
Subfamily:Dolichoderinae
Tribe:Leptomyrmecini
Genus:Linepithema
Taxon Code:HYM00148
ITIS TSN#:575041

LOCATION DETAILS
Location
Morgan Fire Burn Area, Mount Diablo State Park, Clayton
County:Contra Costa County
ECI Site#:CASP175000
Park/Forest:Mount Diablo State Park

RECOGNITION
Workers are usually uniformly light to medium brown. The body is slender; the head ovular to triangular-shaped; mandible with two large apical teeth followed by series of denticles; alitrunk dorsum normally lacking erect hairs; petiole erect. This is the most common ant in either households or agriculture.
Body Length
Workers: 2.2-2.6 mm.

BIOLOGY
Food
Omnivorous. Especially fond of sweets, but will eat anything.
Active Period
Year round. Sometimes more notable indoors when colonies are stressed for water or food, or when weather is extreme.
Nesting
Makes nests in soil, rotten wood, standing dead trees, refuse piles, bird nests, bee hives, under pots or stepping stones, and many other places - sheltered or exposed. Ants will move colonies when food or water is scarce.
Development
Metamorphosis is complete. Colonies have multiple queens.
Importance
This ant is the #1 pest in households and agriculture. It invades homes when weather outside is too cold, too wet or too dry, or when honeydew is washed from foliage by rains. In the summer of 2014, at one of the hottest and driest points of the California drought, these ants were reported to forage widely about households and to bite humans.
Range
Across the southern United States (from North Carolina to Florida, west through the gulf states to the coast of California. Regions with freezing temperatures and with little water limit its range. Native to Argentina and Brazil.

HABITAT

CREDITS
Photographer
Eddie Dunbar

REFERENCES
  • BugGuide [ IMAGES ]
  • Integrated Taxonomic Information System TSN#575041


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