Ant Cow: All You Need to Know – Quick Guide on Their Unique Symbiosis

In the fascinating world of nature’s symbiotic relationships, the alliance between ants and aphids, also known as ant cows, stands out as a captivating example of mutualism.

Found across various ant species, the phenomenon of ant “farming” ant cows has sparked curiosity among researchers and nature enthusiasts alike.

This direct and professional quick guide aims to shed light on the intriguing dynamics of this partnership.

Aphids provide a sugary treat for ants, while the ants, in turn, offer valuable protection to their aphid counterparts from potential predators.

Aphids are also called ant cows, considering the phenomenon of ants feeding on their honeydew.

Milkweed Aphids

What Are Ant Cows?

Aphids or ant cows are insects belonging to the subfamily Aphidoidea, with over 4,000 species that feed on plant sap. They use their piercing mouthparts to extract sap, which can be harmful to young and tender plants.

Despite their small numbers, they can cause damage to larger crops, leading to distorted leaves and the risk of transmitting plant viruses and attracting parasitic wasps.

Aphids have rapid life cycles, maturing in as little as ten days, and their prolific egg-laying necessitates control measures for maintaining a healthy garden.

The Phenomenon of Ant Cow Farming

Ants, those tiny yet industrious creatures known for their remarkable strength, are more than just powerful lifters. Surprisingly, they also exhibit farming behaviors, and their primary agricultural endeavor involves tending to aphids.

Recent studies have shed light on the fascinating dynamics of this mutualistic relationship, where ants act as strict overseers to protect and “milk” aphids for their honeydew in return.

An Iron Fist in the Ant World

At the Royal College of London, research has shown that ants wield an iron fist in managing their aphid subjects. Using various methods, they maintain strict control over their aphid herds.

Adult aphids deemed rebellious are swiftly dealt with as ants bite off their wings, effectively preventing them from straying.

Additionally, ants secrete substances on aphid eggs, inhibiting wing growth and ensuring a loyal and grounded workforce.

Large Milkweed Bug and Oleander Aphids

Mastery of Mind Control

Mind control seems more akin to science fiction, but ants have mastered this technique too. They release pheromones that render aphids docile and willing to follow the ant’s lead, ensuring the herd members remain close and cooperative.

Survival of the Fittest – Selective Herding

Just like humans, ants subscribe to the principle of survival of the fittest. They meticulously select the most productive ant cows for herding, ensuring the prosperity of their aphid colonies.

However, those that fall short in producing enough honeydew or succumb to diseases meet a different fate – becoming a nutritious meal for the ants. This selective approach mirrors how humans cull unproductive animals, such as chickens that stop laying eggs.

The remarkable aspect of this ant-aphid relationship is not merely the ants consuming aphids for protein but rather the delicate balance they strike.

By keeping some aphids alive, the ants maintain a sustainable source of honeydew, ensuring the longevity of this peculiar and mutually beneficial partnership.

The Benefits for Ants: A Sweet Deal with Additional Protein

Being a part of this symbiotic relationship with ant cows, ants receive two valuable rewards.

Firstly, while alive, aphids serve as a source of honeydew, a sugary liquid that serves as a nectar-like treat for ants.

Secondly, when aphids meet their demise, they become a protein-rich meal for their diligent ant counterparts.

When aphids feed on plant sap, they face a challenge – the sap lacks essential amino acids, crucial for their growth and development. To overcome this nutritional shortfall, aphids have evolved a remarkable strategy.

They engage in a symbiotic relationship with endosymbiotic bacteria called Buchnera aphidicola, which helps generate amino acids from the plant sap. As a byproduct of this process, aphids produce honeydew.

Possibly Beech Blight Aphids

Aphid’s Waste, Ant’s Delicacy

While honeydew might be a waste product for ant cows, it holds immense value for ants. Almost entirely composed of sugar, honeydew becomes a nectar-like delicacy for the ant farmers.

To ensure a readily available supply of this sugary treat, ant cows possess a specialized trophy biotic organ, akin to having a tap dispensing beer.

The Role of Ants: Protectors and Harvesters

In exchange for their sweet reward, ants dutifully safeguard their aphid herds from potential predators. As long as the ant cows continue to produce ample honeydew, the ants stand as loyal protectors of their valuable sugar source.

A Balancing Act

However, this seemingly harmonious relationship tilts heavily in favor of ants.

Should the aphids falter in their honeydew production or succumb to diseases, their roles swiftly change, transitioning from being valuable sugar suppliers to becoming a nutritious source of protein for the ants.

In this ecosystem, ants hold the upper hand in the symbiotic dance with aphids.

Benefits for Aphids in this Symbiotic Relationship

In the symbiotic relationship with ants, ant cows receive several valuable advantages that contribute to their survival and well-being.

Aphid Protection

Ants serve as a formidable protection belt for aphids, safeguarding them from potential threats posed by larger insects such as ladybirds and parasitic wasps.

Their vigilant presence creates a shield around the aphid colonies, ensuring their safety and enabling them to focus on extracting nutrients from their host plants.

Guided Relocation

Ants play a crucial role in guiding aphids to new food sources when their current host plant is depleted or faced with calamity.

By laying a trail of pheromones, ants effectively lead aphids to alternative feeding grounds, ensuring their continued sustenance and prosperity.

Rescue Operations during Infestations

In times of danger, ants exhibit a remarkable rescue strategy. When areas infested with aphids are treated with soapy water spray, the surviving aphids are swiftly relocated by the ants to other plants.

This adaptive behavior helps the aphids escape the threat and preserves their populations.

Hygiene Maintenance

Aphids’ secretion of honeydew, while beneficial to ants, can pose risks for the ant cows themselves. The sweet substance can quickly attract black, sooty molds that lead to disease.

Here, ants step in as diligent caretakers. They actively clean off the honeydew from the aphids’ abdomens, ensuring that these tiny creatures remain protected from potential diseases caused by mold growth.

Giant Willow Aphid

Ants and Aphids: A Nightmare for Gardeners

The presence of ants and ant cows in your garden can create a devastating combination, wreaking havoc on your precious plants in more ways than one. This deadly duo employs a two-pronged assault that threatens the health and well-being of your garden.

Aphids: Nutrient Robbers

Firstly, aphids act as ruthless nutrient thieves, relentlessly sucking the life out of your plants. Their insatiable appetite for plant sap robs your garden of essential nutrients, weakening the foliage and compromising the overall health of your plants.

Ants: Defenders of the Aphid Colony

To make matters worse, the vigilant ant defenders thwart any attempts to control the aphid population. Introducing beneficial insects like ladybugs, meant to control aphid infestations, becomes futile in the face of the protective ants.

Ants: Relocation Experts

Even when you resort to insecticides or soapy water to eradicate aphids, the astute ants intervene. They quickly herd the surviving aphids away to other plants, enabling their colony to thrive and perpetuate the infestation.

The relentless movement of aphids to new plants leads to exponential reproduction, creating a recurring nightmare for gardeners.

The synergy between ants and aphids forms an unyielding challenge for gardeners seeking to control their infestation. The mutualistic nature of this relationship ensures that these tiny creatures perpetuate their survival, making the eradication process a formidable task.

Foiling the Ant-Aphid Duo: Effective Prevention Strategies for Your Garden

Stopping the notorious ant-aphid combo from infesting your garden might feel like an insurmountable task. Instead of focusing on elimination, let’s explore preventive measures to create an unfavorable environment for their thriving presence.

Deploy the following methods to keep these troublesome insects at bay:

  1. Use Insect Repellent Plants: Cultivate insect-repelling plants like catnip, cilantro, garlic, and chives in your garden. These natural repellents act as deterrents, discouraging both ants and aphids from settling in your garden.
  2. Use Neem Oil: Apply neem oil, a natural insecticide, on your plants. Neem oil is an effective and eco-friendly solution that disrupts the lifecycle of aphids and repels ants, preventing their colonization.
  3. Insecticidal Soapy Water: Regularly spray your plants with insecticidal soapy water. This simple, homemade solution disrupts aphids’ protective waxy coating and deters ants, making your garden a less inviting habitat for both pests.
  4. Deploy Sticky Traps: Strategically place sticky traps on your plant leaves. These traps act as efficient catchers for aphids, reducing their population and disrupting their ability to infest your garden.

By proactively implementing these preventive measures, you can create an unfavorable environment for the ant-aphid combo, dissuading their establishment in your garden.


In the battle against the tenacious ant-aphid combo, prevention emerges as the key to maintaining a thriving garden.

By incorporating insect-repelling plants, natural insecticides like neem oil, insecticidal soapy water, and sticky traps, you can deter their infestation before it takes root.

With proactive measures, you can reclaim your garden’s beauty and harmony, outsmarting this challenging duo at every turn.

Frequently Asked Questions

What kinds of ants farm aphids?

Various ant species engage in aphid farming, including yellow meadow ants and black garden ants. Yellow meadow ants exhibit livestock-like practices, caring for productive aphids and eliminating weaker ones.

Additionally, species like Lasius niger or black garden ants have also been observed herding aphids.

Do ants enslave aphids?

Though their relationship appears symbiotic, behavioral analysis suggests ants treat aphids more like slaves than equals. Ants protect and tend to aphids for their honeydew but may consume them when they become weak or unproductive.

Are ants effective in killing aphids?

No, ants and aphids share a mutualistic relationship. Ants nurture and protect aphids for their honeydew. They don’t actively kill aphids but safeguard them from beneficial insects, molds, or stress.

Only when aphids cease producing honeydew might ants resort to consuming them.

Do carpenter ants farm aphids?

Yes, carpenter ants cultivate aphids for the sweet honeydew the aphids secrete after feeding on fleshy plants and sap. In exchange for protection, carpenter ants “milk” the aphids by rubbing their abdomens to collect the honeydew from the aphid colony.

Readers’ Mail

Over the years, has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Ant Cows!!

Little static critters
Hello dear bugman.
I noticed these little things on the underside of my pompom viburnam tree’s leaves. What are they??

I have a postage-stamp sized garden in downtown Boston , a few trees and perennials and usually bugs are not a problem; we get bees mostly. Some ants. Although we have had slugs.

We don’t even get mosqiotos! SO I didn’t think I had a real pest, but then I noticed them on the underside of my dead cosmos as well. No other plants seem affected. I think they are pests indeed. Humph! Any idea?

They don’t move much, usually are lumped up together in clusters, they are slightly varied sizes, seem teardrop shaped, and they have a matte charcoal finish to them.

Oh and as you can see, tiny red ants like to crawl all over them. I can’t get close enough to count the legs, they are sooo small! I would love a super, natural solution that works in a tiny backyard (lots of folks close around this garden, so I don’t want to be spraying bad things in the air) Any ideas on my mystery guests?
J Thank you so much! (love the site)

Dear J.,
You have Ant Cows, a common name for Aphids. Aphids are pests which suck the juices from plants and spread viruses, though not to people. Ants “farm” the aphids because of the sticky Honeydew they exude from their anuses.

A mild spray of soapy water on a daily basis will help rid your postage stamp garden from this vile pestilence.

Wow, that is a little gross! Off I go to suds up then… Thanks Bugman!!

Letter 2 – Ant Cows with herder

What are these bugs? huge mass of them
Found it on a few leaves. My first thought was that those were all baby ants or something but in the photo once enlarged on screen, they don’t look like ants. The bigger ants next to the “mass” weren’t attacking it or anything just sitting there looking at it without moving.-
Greg Dunbar

Hi Greg,
Aphids are the bane to a gardener’s existance as they are injurious to plants. They suck the juices from the plants and proliferate rapidly. Aphids are sometimes called Ant Cows since they have a symbiotic relationship with ant.

The Aphids exude a sticky “honeydew” from their anus and the ants just love it. Ants are known to “herd” the Aphids by moving them to other non-infested plants to provide a fresh food supply when the original plant begins to wither and weaken.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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