Why do adult nestmates carry each other (Ken, Poland, Ohio, USA)

I've been watching some ants and baiting them over the past couple weeks. I saw a colony moving larvae to another location. Among the trail were ants carrying other ants. If separated, the one would curl back up, and the other would pick it up and continue on. Why?
Ken, Poland, Ohio, USA


Great observations you have been making on Carpenter ants. It sounds that the ants you were observing were moving to a different nesting site, since you saw them carrying larvae. The behavior you observed of workers from the same nest carry one another when they move to a different nesting site is called "social carrying behavior". It is a remarkable social activity in ant colonies. Scientists have been able to study social carrying behavior in several different ant species. What they found is that different ant species can have a different style of carrying adult nestmates. Ants from the genus Pseudomyrmex, for example, carry an adult nestmate by grabbing it at the base of the mandibles (mouthparts) and curls up onto the dorsal site (that is the back) of the carrying individual. The eyes of the carried individual face forward in this position. This carrying style is called the "parasol-posture". Ants from the subfamily Formicinae, to which Carpenter ants (genus Camponotus) belong, use different styles. The carried individual can also be grabbed at the base of the mandibles, but she is positioned upside-down and curls up under the ventral side of the carrier's head as seen in this picture here. In the ant subfamily Myrmeciinae adult transport is not stereotyped. One worker gasps another at any part of the body and drags it over the ground.


Here an adult worker of the genus Formica (subfamily Formicinae) carries a nestmate using a stereotyped carrying posture.

Adult nestmates carry each other for several reasons, but the most common is when the colony or parts of the colony move from one nest site to another. Social carrying behavior is a recruitment technique similar to tandem running, in which one worker shows a suitable nesting site to the other by running ahead.

Enjoy watching your ants!
Steffi Kautz & the AntAsk Team

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