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House-infesting Ants & Their Management
Bastiaan M. Drees and Bill Summerlin
Professor and Extension Entomologist; Technician II;
The Texas A&M University System
As a group, ants are the most difficult household pests to control. In some cases, treatment methods such as spraying ant trails only make the problem worse! Learning to identify pest ants, understanding their biology and knowing control alternatives will help make combating them a success.
Behavior
Ants are social insects. Their nests or colonies can be found indoors and out, although some species have preferred nesting sites. A nest contains one or more queen ants laying eggs and being cared for by worker ants. Worker ants--sterile or non-reproductive female ants--tend the queen and brood (eggs, larvae and pupae) and forage for food. Foraging ants can invade household from colonies outdoors.
Nests often can be located by following "trails" of foraging ants. Indoors, ants nest almost anywhere. For instance, Pharaoh ants readily nest in attics, appliances, linens, heating ducts, wall voids and light switches or fixtures. Killing foraging ants rarely solves an ant problem in the home because the colony remains unaffected.
During certain times of the year, most species produce reproductives, winged
male and female ants that leave the nest to mate and establish new colonies.
When winged ants swarm in the home, their colony is likely to be located
somewhere inside. Winged ants can be distinguished from termites by three
characteristics (also see Extension publications L-1781, Subterranean
Termites and L-1782, Drywood Termites):
| Winged Ants | Winged Termites |
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The presence of winged ants outside, such as around porch lights, should
not be a concern, although in high numbers they can be a nuisance. Most winged
forms are unsuccessful in establishing a new colony. Turn off porch lights or
use yellow "bug" lights to make these locations less attractive to
them.
Ants form new colonies in several ways. Most are started by a newly mated winged reproductive, now called the queen ant. After finding a suitable nesting site, the queen loses her wings and begins laying eggs, which hatch into legless, grub-like larvae. The queen feeds the larvae as they develop through several stages in which they molt and grow between each stage. Afterward, they form pupae and soon emerge as adult ants. Once worker ants have developed, the queen no longer needs to care for the brood.
Some ant colonies have more than one queen, and mating may occur within the nest without swarming. These ants form new colonies when one or more queen ants, along with some workers and brood, leave the nest and move to a new location. Ant colonies do not nest in permanent locations; frequently entire colonies move from one nesting site to another almost overnight. Particularly during very wet or abnormally hot and dry weather, ant colonies whose nesting areas are flooded or lack of food and water often migrate indoors.
Worker ants foraging for food and water become a concern when they infest food or other items in the home. Although most ants consume a wide variety of foods (they are omnivorous), certain species prefer some types of foods and some even change their preferences over time. Species of ants that sting, such as red imported fire ants, can endanger young children, confined pets and bedridden people.
Foraging workers of some ants establish temporary chemical (pheromone) trails that help other ants find food and water. These species can "recruit" other ants to a resource quickly and in high numbers. Food is brought back to the colony and fed communally among the other members of the colony, including the queen(s) and brood, a process called trophallaxis. For some species, such as Pharaoh ants, larvae are an essential part of the food chain because they digest food brought by worker ants and regurgitate it for the rest of the colony to consume. Without larvae, the colony would starve. Most adult ants cannot ingest solid food particles.
Resources
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin. Individuals with disabilities requiring auxilary aids, services or accommodations in order to participate in Extension programs are encouraged to call 281.855.5600 to discuss specific needs.