Ants pass the winter hibernating. Similar to bears, bats, frogs, mountain pygmy possums and the western diamondback rattlesnake, ants store up energy and fatten up in the fall to then lie dormant during winter months.
Most take cover beneath bark, under rocks, or within the ant hole that will naturally close off from detritus over the course of the winter. Come warm weather, ants awaken and work restlessly to reopen their holes.
A good time to observe ant behavior is when they are working on reconstruction. Ant trails are the result of pheromones deposited by the ants as they travel. Other ants are attracted to the familiar scent and will take the route with the most powerful smell.
Because the strength of pheromones deposited is dependent on the length of the route and the amount of ant traffic, the longer trails have less concentrated pheromones and the pathways used by ants evolve to be the most efficient.
Examination of ant behavior has actually contributed a fair amount to human traffic flow patterns. In other words, people have studied ant colonies and have modeled the patterns observed in ant behavior to help structure traffic flow.
Ants may seem like a small, slightly inconvenient menace at picnics, but fire ants kill about five percent of individuals they sting. Fire ants are actually such a large problem in the southeast that an alien species, the phorid fly, has been introduced to manage the problem.
The flies lay eggs on the ants and when the larvae hatch they eat off the head of the ant.