Ants

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INTRODUCTION
Ants are one of the most successful groups of insects. They are social insects that live in colonies which are usually located in the ground, but they may enter buildings for shelter and/or food. Ants feed on practically every kind of food, but those entering homes are looking for sweets and/or protein-containing substances.
About 700 species of ants occur in the United States and Canada. Of these, only about 25 species commonly infest homes.
By about 2000, pest ants replaced cockroaches as being the most important or most difficult to control of the structural pests; the availability of highly effective baits for cockroaches made this possible.
The biology and habits of each ant species are different, so a detailed knowledge of these for each species is necessary for effective control. 
RECOGNITION
Three body regions (head, thorax, and abdomen) defined by distinct constrictions. Antennae elbowed (workers and queens; males sometimes straight) with last 1-4 segments usually enlarged, forming a club. Abdomen connected to thorax by 1 or 2 slender abdominal segments called nodes which form the pedicel (ant’s waist); enlarged rear portion of abdomen is the gaster.
It should be noted that in ants, what is commonly referred to as the thorax actually includes the fused 1st abdominal segment (= epinotum/propodeum) and is correctly called the mseosoma or alitrunk. The common usage of the thorax consisting of everything between the head and node(s) is used in this Field Guide.

BIOLOGY

Ants have complete metamorphosis: egg, larva, pupa, and adult. They are social insects and the colonies contain 3 distinct castes: workers, queens, and males.

Workers are female, never with wings, and may live as long as 7 years. Although typically thought of as being sterile, workers of many species lay eggs that develop into males or are used by the colony as food (trophic eggs). Workers are either monomorphic, being of one form and size, or they are polymorphic, being of several forms which may vary greatly in size. Small workers are called minors, large ones majors or “soldiers”, and those of in-between size are called intermediates or medias. Workers do all the work in the colony, which includes gathering food, caring for the young, and the enlargement of the nest.

Queens, which are typically the largest ants in a colony, function to establish new colonies and lay eggs. Once inseminated, they can lay fertile eggs for their lifetime which may be up to 30 years (harvester ant queens). For most species, a colony may contain many functional females or queens but only one founding queen. In the more common species, unmated females have wings and mated females remove them. The male is usually between the worker and the queen in size and his only function is to inseminate the queen. Reproductives are usually produced only in very large or old colonies. Males die shortly after mating, usually within 2 weeks. For a particular species, if the females are winged, the males are also winged and retain their wings until death.

New colonies are founded at different times of the year, depending on the species. The swarmers (winged reproductives) usually come out of the nest, mate, and the inseminated queens remove their wings and start a new colony in a suitable habitat. However, Pharaoh ant swarmers produce no external swarm and mate in the nest, with new colonies being established by budding. Argentine ant female swarmers do not swarm externally. Male Argentine ant swarmers sometimes do swarm externally, but mating still occurs in the nest and new colonies are established by budding. All colonies of a particu- lar species tend to swarm at the same time in a given area.

Adult ants, workers and reproductives, do not eat solid food. Instead, they eat only liquids which may be stored in their crop. Workers may regurgitate a tiny droplet of liquid to a fellow ant when solicitated by antennal palpations or stroking. Larvae are fed predigested or regurgitated food. Older larvae may process solid food into liquid form.