With June comes the arrival of many eagerly awaited events. It’s the end of the school year and the beginning of a season of bare feet, beaches, camping trips and baseball games. In my house, one thing we are not excited about is the return of ants that parade around our kitchen. We know these ants are not going to cause us any harm. But, when a horde of them begins an organized march around the rim of my sons’ cereal bowls, it starts to bug me. At the same time, I realize they are just doing their job. It is a highly evolved social structure that allows these ants such precision in the tasks at hand—carrying away crushed Cheerios from the kitchen floor for their own pantries, taking to the air for a ritualized mating flight, deciding which eggs will be fertilized, or starting a new colony from the ground up.
These insects of the scientific order Hymenoptera truly rule the ground, turning more soil than earthworms and comprising roughly 15% of the entire animal biomass in most terrestrial environments. Surprisingly, ants are the top predators of invertebrates that call the soil their home. In addition, these dynamos are responsible for dispersing about 30% of the seeds produced by herbaceous plants in the northeastern United States. Small in size, but mighty in numbers, there are over 8,800 known species of ants in the world. This biological success is contributed in part to their enormous geographic range, which stretches from the Arctic Circle to southern Africa. Another key to this success is their highly social nature, living in colonies that can spread out beneath an entire acre of land.
The majority of ant species have a fairly simple society: one queen, numerous sterile female workers, and a few fertile princesses and male drones. The queen is wingless (after she has mated) and twice the size of other ants in her colony. Her main job is to perpetuate the colony by laying eggs. She controls what type of ant egg is laid. Tucked inside her body is a supply of sperm that was received on her nuptial flight as a princess, which will last her entire life, spanning as long as 20 years. Most eggs that she lays get fertilized and develop into sterile female workers. These workers are the backbone of the ant world, collectively taking on all the building, cleaning, food gathering and feeding duties that keep the colony intact. These workers are the ants most commonly seen by people. Once the colony becomes large and established a select few of the young female larvae are fed more and pampered, which leads to their development into fertile princesses complete with wings. On occasion, the queen will hold back the stored sperm and lay eggs that are not fertilized. These unfertilized eggs develop into the winged male ants called drones.
These winged fertile ants remain in the nest for a few weeks. When the air temperature and humidity are just right, off they go, leaving the nest for their nuptial flights. The princess will release a pheromone, a chemical “perfume,” into the air, creating a mating chase. The princess will mate in flight with drone suitors fast enough to keep up with her. She stashes the sperm in a pocket within her abdomen, ensuring her future as a fertile queen. The male drones die shortly after mating, their role in ant society fulfilled. The now potent princess will quickly shed her wings and dig herself a small chamber in the ground or a rotting log, sealing herself into this new nursery before laying the first batch of eggs in her own colony.
This new queen is not the only ant using pheromones to communicate. These scented chemicals are released from glands to cover the bodies of all ants and are the main form of communication for these insects. Ants pick up 10-20 different pheromone signals with their super-sensitive antennae, which tells them if an approaching ant is friend or foe, if it is needed to rebuild a damaged nest, defend the colony or help gather food. It is a pheromone trail that leads the ants out of their kingdoms and into my kitchen on a reconnaissance mission every summer. This summer, take a few minutes to watch the fascinating social world of ants on their own turf, and visit your closest Lake County Forest Preserve.