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Ant of the Week: Weaver Ants

As you probably know, spiders and birds aren’t the only ones who know how to weave. Weaver ants (mostly ants of the genus Oecophylla) are named because the worker ants use silk produced by their larvae to sew or weave together leaves in trees to make a nest to live in.

Photo by Robin Klein at Wikimedia

To do this, worker ants form a living chain between nearby leaves in a tree and bring leaf edges together. Other workers carry the legless larvae to the edges and give them the signal to spit up silk. As the worker ants move the larvae back and forth, the leaves are bound together into a cluster. The ants use the leafy clusters as nests.

This video shows the workers in action.

Weaver ants are elegant, long-legged ants.

Photo source Sean.hoyland at Wikimedia

Some species of weaver ants are also known as green ants due to the greenish color of their rear sections (gasters). They are called citrus ants or orange ants because they are used to protect fruit in citrus orchards. Weaver ants guard their homes with vigor and attack and eat any arthropods in the vicinity.

Photograph by Axel Rouvin at Wikimedia

As far as is known, the ancient Chinese were the first to use these ants to control pests and protect crops. Around 1,700 years ago, farmers employed weaver ants to keep caterpillars, stink bugs and small rodents out of their valuable citrus orchards. Farmers could stroll down to their local market, buy ant nests full of ants and put them out into their orchards. Evidence suggests the farmers actually provided platforms or runways so the weaver ants could run from tree to tree.

So, that’s ancient history, right? Those were times before pesticides and modern technology. Who needs ants now?

In fact, in the later part of the twentieth century many growers did switch to using pesticides to protect their crops. Soon, because of the high costs of pesticides, and other problems associated with pesticide use, farmers quit using them and began using ants again in their orchards. Today farmers in Asia and Northern Australia rely on weaver ants to control pests of mango, coconut, oil palm and cashew orchards.

I would love to see weaver ants in real life someday. They are amazing.

Have you ever seen weaver ants in action?

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Related:

There is a children's book that describes the ancient Chinese practice of using weaver ants in orchards called Ma Jiang & The Orange Ants by Barbara Ann Porte and illustrated by Annie Cannon.

6 thoughts on “Ant of the Week: Weaver Ants

  1. Roberta

    That is a great question. Recent work suggests that not only do multiple queens come together for founding new colonies (pleometrosis), but those queens that survive colony founding continue living together (polygyny).

    See for example:
    Peng, R., Christian, K. and Gibb, K. (1998), How many queens are there in mature colonies of the green ant, Oecophylla smaragdina (Fabricius)?. Australian Journal of Entomology, 37: 249–253.

  2. Júlio

    Thanks for the article Roberta.
    I'm going to read it later today. I've glanced at the paper and realised why I asked this. I've once read the weaver ant's chapter in Wilson and Hölldobler's book, and there they say that they form monogynic colonies...

  3. Roberta

    Seems like a lot of species are more flexible about accepting multiple queens than originally thought. I wonder if it our thinking is more flexible, or the ants species are changing. Probably the former.

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