Ant Colony No. 1,693 in Jackson, Georgia recently found itself facing a nursery staffing crisis after unforeseen disruptions elsewhere in the colony. Larvae needed feeding. Pupae needed grooming. The entire brood needed sorting. Someone had to keep moving the babies to wherever temperature and humidity conditions were best.
Fred arrived at the nursery with his suitcase, ready to apply.
He looked around for a manager. There wasn’t one. The place was simply full of overworked sisters moving at high speed in every direction while trying to keep eggs, larvae, and pupae alive, organized, clean, and in the right place. Undeterred, Fred began stopping workers as they rushed past.
First he approached a sister carrying an egg. “Can I help?”
She didn’t even slow down. “No wings in the nursery!” she snapped, side-eyeing Fred’s suitcase before hurrying on.
Next he tried a worker who was feeding a larva. “I want to help!”
The exhausted female looked at the line of gaping larvae, then back at Fred. “You have no childcare experience and no relevant qualifications,” she said. “Please leave me alone before one of these larvae decides I’m late.” She immediately turned back to work, just in time for the larva to start demanding more food as if it had been personally neglected for hours.
Still optimistic, Fred approached another sister who was grooming a pupa. “I’m helping,” he declared.
She froze, gave him a long look, and said, “You do not understand a single thing happening in this room. Get out before I call security.”
At that moment, a voice from across the nursery shouted, “Careful, Fred! You almost stepped on a larva!”
Fred glanced down, panicked, and backed toward the exit.
By the time he made it out the door, the colony had reached a unanimous decision: yes, the nursery needed more workers. No, Fred was not one of them.
The Real Story
Ant colonies divide an enormous amount of work among their female workers, and caring for the colony’s young is one of those jobs. The workers who spend much of their time tending the brood are often called nurse workers. Brood care can include feeding, grooming, carrying, and repositioning the developing ants as their needs change.
And there is more going on in an ant nursery than simply keeping track of “the babies.” Ants undergo complete metamorphosis, so the brood passes through several very different stages: egg, larva, and pupa before emerging as an adult. The larvae are the hungry members of the nursery. They depend on adult workers for food, and what they are fed can even differ with the larva’s developmental stage. Pupae, on the other hand, are already undergoing metamorphosis and do not need to be fed, but that does not mean the nursery staff can ignore them. Workers still tend brood through behaviors that include carrying and grooming, and grooming is an important part of protecting developing ants from contamination and pathogens.
Female workers also sort and rearrange the brood rather than leaving eggs, larvae, and pupae wherever somebody happened to drop them. Experiments with ants have shown organized brood sorting, with different developmental stages becoming spatially arranged within the nest. That organization can make brood care more efficient by placing the workers and the developing young where they need to be.
Location matters for another reason: ant development depends on the conditions around the brood. In many species, workers actively move brood through different parts of the nest as temperatures change, taking advantage of warmer or cooler areas to maintain favorable developmental conditions. Ant colonies can therefore regulate the brood’s environment partly through something surprisingly simple: pick up the babies and move them.
Despite all this specialization, the colony’s workforce is not necessarily locked into permanent job descriptions. Ant task allocation can be remarkably flexible, allowing workers to change what they do when the colony’s needs change. Exactly how jobs are divided varies among species, and age can influence which jobs workers are most likely to perform. But that particular employment policy deserves its own scandal.
For now, the important point is that an ant nursery is a surprisingly sophisticated operation. Workers feed the hungry, groom the developing, sort the brood, move them when environmental conditions change, and shift to different tasks when the colony needs change.
Ant colonies manage far more than nursery care, of course, from foraging and defense to sanitation, relocation, and agriculture in some species. We’ll get to those scandals separately.
Fred remains available for consultation. And male.
Sources
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Ant nurse workers exhibit behavioural and transcriptomic signatures of specialization on larval stage
Walsh, J. T., Warner, M. R., Kase, A., Cushing, B. J., & Linksvayer, T. A. (2018). Ant nurse workers exhibit behavioural and transcriptomic signatures of specialization on larval stage. Animal Behaviour, 141, 161–169.
Why this source matters: Primary research on nurse workers on the pharaoh ant Monomorium pharaonis. Supports the article’s discussion of cooperative brood care, including feeding, grooming, and carrying brood, and shows that nurse workers can specialize in caring for larvae of different developmental stages.
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Brood sorting by ants: distributing the workload over the work-surface
Franks, N. R., & Sendova-Franks, A. B. (1992). Brood sorting by ants: distributing the workload over the work-surface. Behavioral Ecology and Sociobiology, 30, 109–123.
Why this source matters: Classic experimental study of brood sorting in ants. Supports the discussion of workers organizing brood spatially rather than leaving eggs, larvae, and pupae randomly distributed within the nest.
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Thermoregulation strategies in ants in comparison to other social insects, with a focus on red wood ants (Formica rufa group)
Kadochová, Š., & Frouz, J. (2014). Thermoregulation strategies in ants in comparison to other social insects, with a focus on red wood ants (Formica rufa group). F1000Research, 2, 280.
Why this source matters: Review of thermoregulation in ants, including brood relocation along thermal gradients. Supports the explanation that nurse workers can move brood among nest locations as temperatures change in order to maintain favorable developmental conditions.