Harvester ants exhibit two foraging patterns.
Typically, large areas surrounding the mound are stripped of vegetation to prevent shading, as harvester ants usually remain within the nest during the hottest part of the day. In a separate experiment where larger glass beads (3.0 mm or larger) were used, smaller fire ant workers crawled through the bigger spaces (0.5 mm or larger) between beads rather than having to move beads to tunnel through them.Harvester ant mounds are moderate to large in size depending on the species. As the videos showed, they can dig tunnels by moving particles up to 2 mm in diameter. Red imported fire ants range in size (they are polymorphic). has not found particle sizes that could be used as a physical barrier to prevent imported fire ant penetration. In order to move the beads, the ants turned around and walked backwards using only four of their six legs! Surprisingly, for 1.0 and 2.0 mm beads, individual ants began using their mandibles (jaws) as well as their first pair of legs to form a “basket” to carry the beads. For larger beads (0.50, 1.0 mm), the number of worker ants carrying more than one bead decreased until each ant carried only one bead per trip. For very small beads (0.01, 0.02 mm), individual worker ants carried many beads during each excavation trip. Video – Fire Ants Carrying 2.00 mm Beads Variationsįor smaller beads (less that 1.0 mm in diameter), the worker ants used their mandibles to carry one or more beads.
Vinson at Texas A&M University ( ) investigated this excavation behavior by videotaping how fire ants move glass beads ranging in diameter from 0.01 to 2.0 mm (see video clips: 0.01 mm, 0.25 mm, 0.50 mm, 1.00 mm, 2.00 mm). During their tunnel digging activities to create their nests or mounds, they excavate soil particles. Worker ants build nests, forage for food, and care for the queen(s) and brood (eggs, larvae, pupae). Red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae) are social insects that live in colonies. Others may appreciate the teamwork exhibited by these harvester ant workers.Īn array of sizes of fire ants compared to the fire ant queen. Movement of the dime on the surface is reminiscent of a planchette or movable indicator point on a ouija board (correctly pronounced “wee-jah” although often pronounced “wee-gee”)! Repeating this experiment, we have found that worker ants of some colonies move the dime into rather than away from the nest entrance. She was able to capture the response of the worker ants as they worked together to move the dime away from the clearing around that opening.
For more information on this ant species, see the publication Red Harvester Ants.ĭuring her graduate studies at Texas A&M University, Nancy Nicholi was taking the following video when a dime dropped from her pocket onto the ground near the nest opening. The circle contains many small pebbles carried out by the ants as they dig their subterranean living space. Nests of red harvester ant, Pogonomyrmex species, usually have one central opening in the middle of a circular area that has been cleared of vegetation by the ants.
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