ant farming?

True or False:  among all the species in the animal kingdom, only humans are known to domesticate other animals for their own use.

You can probably guess from the title of this post that the statement may be false.


Is this ant just a random passerby, or is it performing some other function sitting near this dense patch of yellow aphids clustered on a milkweed stem?  There is a spider hovering in the top right corner — is the ant there to protect this aphid colony?

There are numerous reported examples of the ways in which the highly organized society of an ant colony manipulates certain species of sap-sucking bugs (Hemipteran species) to harvest the sugar and protein in the bug’s excreta.


Aphids feed on plant sap by sticking their proboscis directly into the phloem tubes that carry photosynthesized sugars from the leaves to other parts of the plant.  As the bugs fill up with plant sap, clear liquid droplets called “honeydew” form (top right of image) at the tip of their abdomen.  Ants can harvest the energy in this “waste” product for their own benefit.


Ant feeding on aphid “honeydew”. Photo by Charles Chien,

Ants protect their “herd” from predators by swarming them and driving them away, they transport the herd to new leaves on which to feed, they move them to sheltered locations during downpours, all to maximize the nutrient-rich output of the herd’s excreta.  Ants also excrete a substance that reduces movement of their herd, so that they stay put in one place, and they have been observed to bite off the wings of the breeding females so they don’t disperse from the feeding area, but instead produce more offspring in situ.  So, it really is farming…in quite a sophisticated way.  This is illustrated beautifully in a video on — please click on this link to see it:

6 thoughts on “ant farming?

  1. Those ants have an extremely evolved behaviour pattern but I am sure the ants here do not too badly in tending aphids on my broad beans, if I let them. They are not just opportunistic. The bees that take honeydew see it as just another sugar source. However, I am glad that we don’t get that sort of honey around here (that is just because I do not have a good relationship with aphids :)) Amelia

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