Nest Building by Weaver ants

My garden has several nests of weaver ants(Oecophylla smaragdina). Even though I have captured their closeups and nests, after it was constructed, I wanted to witness and capture the nest building steps of this brilliant insect architect. After stalking several nests and getting bitten by their workers, I was finally able to get a good look at such a nest building activity on mulberry (Morus australis) bush. I was using my Canon EOS 5DMark III along with Canon EF 100mm f/2.8L Macro IS USM. I used Canon MT-24EX macro twin light flash to illuminate it. All of these are un-cropped nearly full frame images.

Weaver ants (Oecophylla smaragdina) are eusocial insects of the family Formicidae of the order Hymenoptera. Weaver ants live on trees and are known for their unique nest building behavior where workers construct nests by weaving together leaves using larval silk. Colonies can be extremely large consisting of more than a hundred nests spanning numerous trees and contain more than half a million workers.

The weaver ant’s ability to build capacious nests from living leaves has undeniably contributed to their ecological success. What we are witness in these photos is the first phase in nest construction. It involves workers surveying potential nesting leaves by pulling on the edges with their mandibles. When a few ants have successfully bent a leaf onto itself or drawn its edge toward another, other workers nearby join the effort. The probability of a worker joining the concerted effort is dependent on the size of the group, with workers showing a higher probability of joining when group size is large.

When the span between two leaves is beyond the reach of a single ant, workers form chains with their bodies by grasping one anther’s petiole (waist). Multiple intricate chains working in unison are often used to ratchet together large leaves during nest construction. Since mulberry has smaller and closer leaves we see only line of single workers are able to hold the leaves together.

Once the edges of the leaves are drawn together, other workers retrieve larvae from existing nests using their mandibles. These workers hold and manipulate the larvae in such a way that causes them to excrete silk. They can only produce so much silk, so the larva will have to pupate without a cocoon. The workers then maneuver between the leaves in a highly coordinated fashion to bind them together.

Weaver ant’s nests are usually elliptical in shape and range in size from a single small leaf folded and bound onto itself to large nests consisting of many leaves and measure over half a meter in length. The time required to construct a nest varies depending on leaf type and eventual size, but often a large nest can be built in significantly less than 24 hours. Although weaver ant’s nests are strong and impermeable to water, new nests are continually being built by workers in large colonies to replace old dying nests and those damaged by storms.

I did not want to disturb them beyond their comfort zone. Already bitten by several workers for going very close to their nest construction, I stopped shooting and watched them from far and enjoyed the great work they did in group. It took them over a day to finish their intricate stitching process. I will cover those photos in my blog later.

Their work reminded me of this great quote from J.K. Rowling in her book Harry Potter and the Goblet of Fire

We are only as strong as we are united, as weak as we are divided.

Check my earlier blogs on Weaver ants and Weaver Ant – Oecophylla smaragdina for more details and videos.