The Fire Ant Colony and
Life Cycle
Excerpts from Steve Tvedten's book "The Best Control
(2nd Edition)"
The Fire Ant Colony and Life Cycle
The life cycles of the four described fire ant species are all very similar.
Development of the individual: Like all ants, an individual fire ant begins life as an egg, which hatches into a legless, grub-like larva. The larva is very soft and whitish in color. It is also helpless and depends totally on worker ants for food and care. The fire ant larva is specialized for feeding and growing, and almost all growth occurs during this period. As in all insects, growth is accomplished by periodic molting, or shedding of the cuticle (skin) using an enzyme zipper. Having reached its final size, the larva becomes a pupa in which various adult structures, such as legs, and in some cases wings, become apparent for the first time. The fire ant pupal stage is the transitional stage between the larva and the adult that emerges during the final molt. In insects in general, the adult stage is specialized for reproduction and dispersal; with ants, some adult individuals are capable of reproduction (queens and kings) and the remainder are sterile workers.
The fire ant colony: The social unit of fire ants contains several hundred to several thousand related members depending on the age of the colony. Colonies, like individuals, pass through a characteristic life cycle. New colonies do not make a conspicuous mound for several months. Older colonies may have mounds up to 3 feet in diameter. Mounds are usually found in open sunny areas such as lawns, pastures and fields, but may also be found in logs, around trees and under pavement. There may be 20 to several hundred mounds per acre. Occasionally fire ants can be found nesting on the roof or debris on the roof or in an electric receptacle, but most often they are found in the ground. There are several pheromones used by fire ants; the key recruitment chemical is an alpha-farnesene which is supplemented by 2 or 3 other chemicals.
Fire ants feed on many things, including insects, oil from seeds, meats, grease and honeydew. The ants cannot eat solid food, and must extract or liquefy the food source. This liquid food is passed to the other ants in the colony including the queen and the developing young ants or brood. Worker ants search for food up to 100 feet away when the temperature is between 70o F. and 90o F. during the day or night. When temperatures exceed 95o F., fire ants only forage night. Their foraging tunnels can be 50 - 100 feet long.
Fire ants are very typical of ants in general. In addition to workers and a queen, mature colonies contain males and females capable of flight and reproduction. These individuals are generally called “reproductives.” The average colony can produce about 4,500 reproductives per year. On a warm day, usually one or two days following a rain, the workers open holes in the nest through which the reproductives exit for a mating flight. Mating takes place 300' to 800' in the air. Mated females (are attracted to shiny surfaces) descend to the ground, up to 12 miles away, break off their wings, and search for a place to dig the founding nest, a vertical tunnel 2" to 5" deep. They seal themselves off in this founding nest to lay eggs and to rear their first brood of workers. During this period they do not feed, instead utilizing reserves stored in their bodies. The first worker brood takes about a month to develop; these are the smallest individuals in the entire colony cycle. Fire ants open the nest, begin to forage for food, rear more workers, and care for the queens. Hereafter, the queen or queens essentially become egg-laying machines, each able to lay up to 1,500 to 1,600 eggs per day and can live 2 - 7 years. If the colony is disturbed, the workers swarm over the mound for 8 minutes; if the disturbance continues, the workers will quickly carry the queen through underground tunnels so she can begin a new colony.
Multiple fire ant queen colonies are fairly common. A single colony may have 10 to 100 or more queens, each reproducing. Multiple queen colonies can mean up to 10 times more mounds per acre. The fire ant queens generally mate several times and may live for up to 6 - 7 years. Workers are less long-lived and usually will not survive an entire season. Each queen can lay from 1000 to 1500 eggs a day for up to 7 years!
The fire ant colony grows rapidly by the production of workers that gradually enlarge the original vertical tunnel into multiple passages and chambers. Colony maturity is attained when fire ant reproductives are once again produced. The reproductives leave to mate and form new colonies. A mature colony of Red Imported Fire Ants can produce as many as 4,500 reproductives during the year in 6-10 mating flights between spring and fall. Mating flights usually occur about 1 - 2 days after a rain on warm, sunny days about 10 a.m. Nearly 100,000 queens may be produced per acre in heavily infested land, but mortality rates, mostly from natural predators, can reach 99%.
Fire ant colony size: Colonies of Red and Black Imported Fire Ants become
territorial as they grow; they defend their territory area against all
other fire ants. Therefore, fire ant colony populations often reach
an upper limit depending on the territory size of mature colonies.
A typical figure for pasture land seems to be about 20-50 mounds or more
per acre in single queen nests and up to 250 mounds or more (up to 700)
in multiple queen nests. Mature colonies of Imported Red Fire Ants
consist of an average 80,000 workers, but colonies of up to 240,000 and
more have been reported.