Formicidae  

The Formicidae are the ants, social insects. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than 12,500 out of an estimated total of 22,000 species have been described. They are easily identified by their elbowed antennae and a distinctive node-like structure that forms a slender waist. Ants form colonies that range in size from a few dozen predatory individuals living in small natural cavities to highly organised colonies which may occupy large territories and consist of millions of individuals. These larger colonies consist mostly of sterile wingless females forming castes of workers, soldiers, or other specialised types. Nearly all ant colonies also have some fertile males called drones and one or more fertile females called queens. Ants have colonised almost every landmass on Earth. The only places lacking indigenous ants are Antarctica and a few remote or inhospitable islands. Ants thrive in most ecosystems, and may form 15–25% of the terrestrial animal biomass. Their success in so many environments has been attributed to their social organisation and their ability to modify habitats, tap resources, and defend themselves. Their long co-evolution with other species has led to mimetic, commensal, parasitic, and mutualistic relationships. Ant societies have division of labour, communication between individuals, and an ability to solve complex problems. These parallels with human societies have long been an inspiration and subject of study. Many human cultures make use of ants in cuisine, medication and rituals. Some species are valued in their role as biological pest control agents. Ants come into conflict with humans, as they can damage crops and invade buildings. Some species, such as the red imported fire ant, are regarded as invasive species, aggressively establishing themselves in areas where they are accidentally introduced.

Bolton (2003) gives the following list of general synapomorphies for the Formicidae (but note that several of these are not unique to ants and have evolved independently in other vespoids, and that several have been secondarily lost in certain ant lineages):

• Eusocial, with perennial colonies
• Wingless worker caste
• Females with prognathous heads
• Infrabuccal sac between labium and hypopharynx
• Antennae elbowed (geniculate) between the funiculus and the elongated scape (scape short in the primitive subfamilies Armaniinae and Sphecomyrminae)
• Metapleural gland in females
• Abdominal segment II differentiated, forming a petiole (weakly differentiated in the primitive subfamily Armaniinae)
• Wings of alate queens shed after mating
• Mating performed in mass nuptial flights
• Forewings always lacking cross-veins 3rs-m and 2m-cu

The School of Ants project is a citizen-scientist driven study of the ants that live in urban areas, particularly around homes and schools. Participation is open to anyone interested in contributing.

Air scoops provide cooling: ants
 

Air scoops on the sides of ants cool them through evaporation.

 
  "Another reason ants succeed so well is that they're superb lawn-traversing machines. When this first one backs away from the shadow of the giant human and reenters the main part of the sunny, hot lawn, little air-scoops on its side automatically switch on. A mist of cooling water vapor puffs upward from them. That keeps the ant's temperature down, but it could also mean that the ant's nitrogen--the equivalent of our urine substances--would become overconcentrated." (Bodanis 1992: 39)
  Learn more about this functional adaptation.