|Urban Knowledge Master
longipes (Jerdon) , Long legged ant
Paratrechina longicornis (Latreille), Crazy ant
Pheidole megacephala (Fabricius), Bigheaded ant
Plagiolepis alluaudi (Emery), Little yellow ant
Tapinoma melanocephalum (Fabricius), Tiny yellow house ant
Julian R. Yates III
Extension Urban Entomologist
College of Tropical Agriculture and Human Resources
University of Hawaii at Manoa
As a group, feeding habits are wide ranging from sweets, greasy materials, starch, and plant and animal materials.
Some species of ants, such as fire ants, can inflict a painful sting. One species, Solenopsis geminata (Fabricius), in Hawaii belongs to this group of ants and can be a serious nuisance in recreational areas (parks, school grounds, etc.).
Ants in Hawaii are primarily a nuisance in and around the home and do not cause serious damage. This is particularly true of the Hawaiian carpenter ant which is very much unlike its wood-eating Pacific Northwest relatives.
Ants are social insects, like honey bees and termites; they have distinct caste members within the colony. Each caste performs very specialized duties that contribute to the function and survival of the colony. Primitive species are solitary and live in small colonies, while colonies of more advanced species may contain thousands of individuals.
Typically, an ant colony will contain one or more wingless, egg-laying females (queens), winged virgin females, winged males, wingless sterile female workers, and soldier.
Adult ants, workers and reproductives do not eat solid food. They eat only liquids which may be stored in their crop. Workers may regurgitate tiny droplets of liquid to a fellow ant when solicitated by antennal palpitations or stroking. Larvae predigested or regurgitated food. Older larvae may process solid food to liquid form.
After mating, the queen drops her wings and seeks a suitable place to start a nest. While the queens of some species will found new colonies (one queen per colony), queens of other species will return to an established colony to lay eggs.
When a queen's first batch of eggs hatches, the larvae are fed either a secretion she produces or the extra eggs. Larvae take about four weeks to develop.
The subsequent pupal stage approximately takes three or four weeks to develop.
Adults in the first batch are few and smaller than normal; they emerge from the nest to forage for food to feed the second larval brood. The queen then becomes an egg-laying machine.
Queens may live from 12 to 15 years, workers three to four years; colonies may persist indefinitely.
Ants are social insects, like honey bees and termites; they have three distinct caste members within the colony-queen, male, and worker. The soldier is a large worker. Each caste performs very specialized duties that contribute to the function and survival of the colony. Primitive species are solitary and live in small colonies, while colonies of more advanced species may contain thousands of individuals.
There are some 40 to 45 species of ants in Hawaii, and although not all are pests of homes and gardens, a few species can be troublesome when they invade your kitchen, bathroom, and plants.
Ant control in and around the home requires multiple plans of attack, persistence, and a knowledge of their social habits. With one or two exceptions, it is not always necessary to know which type of ant you have. Control measures are often the same.
An exception may be the Hawaiian carpenter ant. It does not bore into wood as some mainland species do; however, it is often found nesting indoors inside hollow spaces such as doors, pianos, storage boxes, and termite-eaten wood. Elimination of the nest is the easiest and fastest method of control.
The second exception to general ant control is encountered with the Pharaoh ant. Chemical control (sprays or dusts) applied to foraging workers may split the colony and create one or more satellite colonies. This may result in a larger number of ants, which can complicate control efforts. The use of a slow-acting poison incorporated with an appropriate bait appears to be the best method of control.
Physical exclusion and sanitation are probably the most feasible non-chemical management tools for ants. Obvious entry points into a home should be caulked, food should be refrigerated and/or bottled, floors and counter tops should be free of food debris, etc.
Removal of plants attractive to ants, tree and shrub trimming to eliminate entrance via branches, reducing moisture sources including condensation, sealing pipe and utility line entrances are other methods of non-chemical control.
If a trail of ants is discovered, it is often possible to keep them out by tracing the trail back and sealing the entry point with caulking or applying a pesticide spray to only that area. The spray will disrupt their foraging trail, and indoor foragers will probably abandon their efforts Spraying all visible ants is often unneeded. Chaulking and spraying at the point of entrance may cause the ants to find another entry point into the home.
If one can follow the ant trail to the nesting site, control measures will be more direct. This is done by surveying the outer perimeter, if the house is on a concrete slab, or surveying the perimeter and underside of post-on-pier homes. Look for trails of ants and follow them back to locate the nest, which may be marked by disturbed soil or by a hole with a lot of ant activity. At the nest there will be many individuals as well as whitish capsules, which are the larvae and pupal (growth stage) cases. Treat the nest site and area around it with an insecticide approved for outdoor ant control.
If outside ant activity is not found as a source for indoor problems, the ants may be nesting inside the home. If the nest cannot be found indoors, poison bait may be a solution.
Poison baits are an attractive alternative to other control methods, because you do not have to treat a large area or know exactly where the nest is. When this method is chosen, it is absolutely necessary not to use insecticide sprays or dusts. For the poison bait to work, forager ants must eat the bait and then live long enough to carry it back to the colony to feed the reproductives, other workers, and developing young.
The success of the poison bait to eliminate an ant colony depends on several factors. First, the workers must be attracted to the bait. They will not be if there is other food around or if the bait is unsuitable. If they are not attracted to the trap, try another brand. An alternative would be to experiment to determine what they like. Try a water solution containing table sugar. Place a drop next to an ant trail and see if they readily feed on it. If not, try unused or room-temperature leftover cooking oil, but be aware that oils can become rancid and repellent to ants. Add one or two drops of the attractant to the commercial trap and repeat the experiment. If the ants enter and exit the trap in large numbers, do not disturb the area; allow them to forage. Remember, do not use insecticidal sprays or dusts.
Second, the poison bait must be lethal and slow-acting. If many ants die too soon, live ants will abandon trap area. Third, the trap must be placed where the ants can find it, such as along trails or next to entry points. Even if all goes well, it may take several weeks to eliminate the colony.
The insecticides used in bait traps vary according to brand. They may contain such ingredients as arsenic, boric acid, chlopyrifos, or hydramethylnon. Traps also come in various configurations, which is a factor to consider before purchase if children and pets will be present. Consult your local pesticide distributor.
Broadcast application of pesticides for preventive ant control inside or outside the home is not recommended. Pesticides labeled for ant control do not last and will require repeated applications. This may result in unnecessary added expense and dangers to the environment.
Without persistent treatment, the ants may refuse to leave; or they may return after a time, regardless of the treatment. If that happens, call a professional exterminator for advice and service.
Smith, Eric H. and Richard C. Whitman. 1992. NPCA Field Guide to Structural Pests. NPCA.
Yamada, E. 1982. Ants. In Vector control manual. Vector Control Branch, Hawaii State Health Department, Honolulu.