Formica ulkei

Acid Ant
Formica ulkei


Acid Ant Formica ulkei workers covering nest with leaves
Acid Ant Formica ulkei workers covering nest with leaves. Aug 25, 2004 Wheatley, Ontario.
Acid Ant Formica ulkei worker side nest entrance
Acid Ant Formica ulkei worker at side nest entrance. Aug 23, 2005 Wheatley Provincial Park, Wheatley, Ontario.

Head: Shiny brown to black; red on lower half of face. Back of head has a concave shape. Male all black.
Antenna: Yellowish-red. Male black.
Thorax: Dull yellowish-red. Base of thorax has a darker patch across. A few golden hairs. Queen more shiny, thorax sides dark brown.
Wings: Tinted brown with pale brown veins and stigma.
Legs: Darker yellowish-red than the thorax. Golden hairs.
Abdomen: Shiny black. Golden hairs. Queen has longer, lighter-colored hairs.  Male abdomen black with reddish-brown tip with grayish hair.

Size: Worker 3.5 to 6 mm. Queen 7.5 to 9 mm. – considered small. Male 7 to 8 mm.

Habitat: Near water – edges of swamps, marshes, fens, sedge meadows and wet prairie.

Food: Varied – honeydew from aphids, treehoppers. Tussock Moth Halysidota species larvae.

Flight Time: Late June to early July, mornings at 60 degrees F.

Life Cycle: Nests are constructed deep underground with the excavated material forming a flat mound above the nest.  A number of entrance holes are located around the mound near the base or slightly up the sides.  Mounds may be covered with a thin layer of plant debris.  Mound size ranges up to 122 cm in diameter by 45 cm in height. Usually near water, the lower tunnels are always moist, and attract many other nest mates requiring moisture. Nest mates include Ladybugs, Lacewings, Flower Fly Microdon; Beetles, especially Rove Beetles Megastilicus and Atheta, but also Click Beetle Melanotus and Scarab Flower Chafer Phyllophaga.

Will temporarily take in Formica fusca queens. Nests have also been found with F. subsericea present in equal numbers. Also, F. ulkei nests have been found to contain Solenopsis molesta (thief-ant) colonies in the upper portions. Their tunnels are much smaller and F. ulkei workers cannot get into them.

Comments: Listed for Ontario by Natural Heritage Information Centre. Not on any lists for Essex or Kent county, but present.

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