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Eusocial Insects: We Aren’t the Only Ones with Complex Societies

By Linda Ray


What we humans see when looking down on an ant hill is a mound of dirt with a hole in the middle. What is underneath is an intricate social and structural system that can support sometimes very large numbers of members. As it turns out, humans aren’t the only social creatures. Many insects like ants and bees are, too. 




When we say some insects are social, what does that mean? Entomologists might say that social insects participate in an exchange of interactions and behaviors that form a social organization. Evolutionarily speaking, there is a continuum of insect social structures that goes from solitary, sub social, quasi social and eusocial insects (true social) with various characteristics defining each group. The eusocial groups evolved independently into several orders with the two main insect orders, Hymenoptera (bees, wasps, and ants) and Blattodea (termites), being the most populous. These societies are characterized, at a minimum, by their inter-generational living, a division of labor between members, and cooperative brood care. This societal approach opens up the possibility that they can thrive for decades.  

To fully get a picture of these superorganisms, picture a world where there is a caste system that is determined by either behavioral, genetic, or morphological (appearance) qualities. Workers can be foragers, nurses, scouts, patrollers, nest keepers or gardeners (some grow fungi for food), to name a few.  Brood caregivers tend to be sterile female workers of smaller size while soldiers are females of usually larger size and have large mandibles.  The reproductive division of labor includes the queen laying eggs, her male paramours and workers caring for the queen, eggs, and larvae and, in some species, stepping up to the plate for reproduction if necessary.

There is advanced communication among colony mates for ringing alarms and for colony defense, care of the queen and food alerts. This communication can be chemical (pheromones), auditory, visual, or tactile (such as the waggle dance of honey bees). The queen along with every member has her role to play for the benefit of all. Perhaps this is an example of true socialism in play. In the termite world a caste can be changed depending on need, but you are what you are born into in the Hymenoptera cities. 

There are some unique roles and duties assigned to various workers. For instance, when soldier ants attack a termite colony to steal their larvae for food, a battle rages. There are casualties and wounded soldiers that are assessed by soldier “medics” and triaged. If the wounded are missing 1-3 legs, they release a “help me” pheromone and are rescued. If missing four or more legs, no pheromone is released, and they are not rescued. The rescued are tended back in the nest by workers with a 90% survival rate. So, triaging the wounded originated millions of years ago before humans even existed.

In another example of a unique role, honeypot ants have specialized workers called repletes. These workers consume large amounts of food until their abdomens swell. Their sole job is to store this nectar until times of need and then make it available to members through trophallaxis (regurgitation). Then there are the door wardens. These are worker ants whose life is given over to using their flat round heads to block and unblock entrances to the outside world, thus guarding the nest from intruders.    

Some of the latest research has suggested that bumble bee workers have been found to learn by watching other more experienced bees as they assist each other, wait for assistance, and play with rolling balls. These are examples of eusocial characteristics that are just being discovered.

These observations raise an interesting question about the culture and social learning of eusocial insects. Are these signs that some insects might be sentient? Can they perceive and feel? Future research will tell, but the next time you see an ant, consider it may be more like us than you think.




Sources: 

•Butler, R. 2024. Intro to Entomology. Eagle Hill Institute, Stueben, Maine

•Chittka, L. 2023. Researching the Cognitive Capabilities of Bees. BSAVA Companion, pp 24-25.

•Engle, M. S. 2018. Natural Histories Innumerable Insects: The Story of the Most Diverse and Myriad Animals on Earth. American Museum of Natural History, Sterling Press, New York, NY


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