INTRODUCTION. This species gets its common name from its very pale yellowish to almost whitish tarsi or “feet.” It is probably from the Indo-Australian region and is now found throughout much of the Pacific basin. In 2003, it was found in the British West Indies. It was observed in Florida as early as 1922 and is now known from Hawaii, Florida, California, Tennessee, South Carolina, and Louisiana. It has been spread by commerce, such as in nursery stock and shipping containers.
RECOGNITION. Workers monomorphic, about 1/8" (2.5-3 mm) long. Body is black to brownish black, antenna with apical segments usually paler, and legs with pale yellow¬ish-white tarsi. Antenna 12-segmented, without a club. Thorax lacks spines, profile unevenly rounded. Pedicel 1-segmented, but hidden/concealed from view from above by base of gaster. Gaster with anal opening slitlike, lacking circlet of hairs. Stinger absent.
SIMILAR GROUPS. (1) Odorous house ant (Tapinoma sessile) with tarsus not much paler than tibia, give off sweetish rotten coconut odor when crushed. (2) Ghost ant (Tapinoma melanocephalum) with head and thorax dark, abdomen and legs pale. (3) Crazy ant (.Paratrechina longicornis) with legs very long in relation to body size, antennal scape (1st segment) at least 2 times head length, anal opening circular, surrounded by circlet of hairs. (4) Other small ants with node(s) of pedicel not hidden and/or anal opening circu¬lar, surrounded by circlet of hairs.
BIOLOGY. Mature colonies are large to gigantic, with an estimated size of 8,000 to 3 million individuals and as many as 50% being reproductives. Main colonies are often interconnected to many smaller satellite nests within a given area. New colonies are often formed by budding. Winged males and females swarm in large numbers, typically between July and August in South Florida.
Other than the founding king and queen, nearly 50% of the individuals in a colony are reproductives that are called intercastes. These intercastes are wingless males and females that also mate and lay fertile eggs. The dealated founding queen is eventually replaced by the intercastes.
In contrast to most ants, foraging whitefooted ants do not regurgitate and share their food with other ants. Instead, many of the sterile workers in the colony lay unfertilized, sterile eggs. Such eggs are called trophic eggs and serve as the food source for the lar¬vae and the non-foraging adults within the colony.
HABITS. This is an arboreal species that prefers to live in trees and shrubs where they like to nest in the moist microenvironments of tree holes and crotches, under loose bark, at the base of palm fronds, in decayed tree trucks or branches, and in old termite galleries. However, they will also nest in compost piles, under rocks, in loose mulch, in leaf litter on the ground and in rain gutters, and in outdoor furniture. In addition, they will nest in wall voids, attics, cardboard boxes, around skylights, and under roof shingles. Homeowners typically complain when the ants are found in kitchens (including inside appliances) and bathrooms, trailing on exterior walls, and the alates swarm around skylights, especially in bathrooms. Preferred nesting sites are near moisture and food sources that also provide protection from predators and harsh environmental conditions.
They prefer not to forage during the heat of the day and do forage during the night. They prefer to feed on honeydew and nectar, and will readily invade homes in search of sweet liquids and water. They do feed on dead insects and other protein. They lay pheromone trails to food sources, and the trail of foragers is often an inch (25 mm) or more in width. Foragers tend to follow lines and edges and frequently enter structures via electrical lines and cables.
CONTROL. The fact that the foragers do not feed the stay-at-home members of the colony with what they find and consume via trophallaxis, their extremely high reproductive rate, and their primarily arboreal habits result in some unique control problems. An I PM pro¬gram will give the best results. First, follow the ant foraging trails back to the nests and treat these directly with an appropriately labeled pesticide. Then, eliminate all favored harborage locations possible, that is, all items or objects on the ground such as rocks, wood, concrete/resin objects, etc.
Since this is an arboreal species that prefers to spend its time up off the ground in trees, shrubs, and other vegetation, all contact of vegetation to the structure must be eliminated. Because this species is a honeydew feeder, all vegetation near the structure should be appropriately treated to eliminate honeydew-producing insects such as aphids, scale insects, and mealybugs. This requires a lawn and ornamental license in most states. Since this species is also a nectar feeder, all plants that have large showy flowers with sweet nectar should be eliminated or relocated to areas far away from the structure. This includes most fruit trees, hibiscus, gardenias, etc.
The exterior of the structure should have all possible ant entryways sealed. If this is not possible, treatment of cracks and crevices with a long-lasting dust is advisable. Then it is advisable to do a perimeter treatment of the structure with a highly-repellent pesticide. If the ants are coming from adjoining property or properties, then the repellent pesticide may also need to be applied at the perimeter of the customer’s property to discourage invasion from adjoining properties.
Baiting is useful because if enough of the foragers die, the reproductive females and larvae will die of starvation. It is probably most useful for nests located up in trees that cannot be reached otherwise. To avoid disturbance, bait stations are probably best located up in the tree or on the tree trunk, or place bait in protected stations on the ground at the base of the tree. Sucrose-based baits containing boric acid are most effective.