Ants: The Clean Up Crew

Many species of ants are scavengers. They pick up what others leave behind.


Take this chip, for example.


Someone had spilled some chips on the ground. Those ants are doing a terrific job of cleaning up the mess.


This is a kibble of dog food someone had tossed out at a highway rest stop.


Ants also clean up dead animals.


Here’s a dead cricket that fell on the sidewalk.


It won’t be long before it is processed and hidden away underground.

Imagine what our world would look like if these creatures didn’t clean up for us.

Chimps, Gorillas and Ants

Once again, our post today is inspired by a book, in this case two children’s books about Jane Goodall and her research. I’m reviewed the books at Wrapped in Foil and wrote about Jane Goodall’s early scientific career at Growing With Science.

In 1960, the famous primatologist Jane Goodall recorded an amazing event. She observed a chimpanzee poke a blade of grass into a termite mound. The termites clamped themselves to the grass in an effort to protect their colony from the intruder. After a short time the chimp pulled the grass back out and ate the insects clinging to it. Goodall’s observations were the first recorded evidence of an animal other than a human using a tool.

But what does this have to do with ants? Since her discovery, Jane Goodall and many others have watched chimps eating ants as well. One way a chimpanzee gathers ants to eat is using sticks or pieces of grass to probe nests of ants. First a chimpanzee opens the nest a bit by digging with its hands. Then the chimp pokes a stick into the opening. The furious ants bite the offending stick in an effort to defend their colony. The chimp then draws the stick out loaded with ants. The chimp either shoves the stick directly into its mouth to eat the ants, or removes the ants with its hand and pops them into its mouth like popcorn. What a yummy snack!

The second way a chimpanzee gathers ants is to pluck a nest of weaver ants from a tree. Weaver ants form nests by tying leaves together with the silk produced by larval ants. Although weaver ants lack a stinger, they do have a painful bite. To avoid the bites of the ants, the chimp quickly runs from the tree with the nest and then crushes it on the ground, preventing any stray workers from biting. Once crushed, the chimp simply pulls the nest apart and eats the flattened ants at its leisure.

What about another African primate, the gorilla? At first many researchers thought gorillas were strictly vegetarian, but then evidence began to mount that they also enjoy munching on ants, very smelly evidence. It turns out that the best way to check what gorillas are eating is to find their feces or dung, and look at what is inside, including ant remains. The studies showed that some groups of gorillas ate quite a few ants during certain times of the year. Gorillas have also been observed and filmed eating ants. They don’t just consume the ants accidentally while eating plants. No one knows for sure why gorillas eat ants, but probably the same reasons other animals do, to obtain certain nutrients or possibly as a form of medicine.

Edit: I forgot I had this link to a video of a weaver ant nest (also called green ants).

Meat Ants Versus Cane Toads

Researchers recently discovered a way to control cane toads, an introduced pest, in Australia:  put out cat food for the meat ants, Iridomyrmex reburrus.

Sound a bit far fetched? It turns out that when scientists scattered cat food along the banks of cane toad-infested ponds, the meat ants would come to the shore to pick it up. If they encounter young cane toads emerging from the water while foraging there, the meat ants attack. In fact, in the study area 98% of emerging toads were laid into by ants within two minutes of leaving the water.

You might wonder if desirable species of toads meet the same fate. It turns out that other kinds of toads evade meat ants at all costs. Only the cane toads freeze in position long enough to for the meat ants to overwhelm them with their tough jaws.

What’s so bad about cane toads? The cane toads were introduced into Australia in an effort to control another pest in sugar cane (thus the name). Soon is became evident that when carnivorous vertebrates – marsupials, lizards, snakes or crocodiles- tried to eat a cane toad, they would succumb to its toxins. With so many cane toads, the threat to wildlife is a very real one.

Is the idea of using ants to control pests a new one? No, certain ants have been used by humans to control pests for centuries. As far as is known, the ancient Chinese were the first to use ants to protect crops. As long as 1,700 years ago, farmers employed weaver ants to keep caterpillars, stink bugs and small rodents out of their valuable citrus orchards. Today weaver ants are used to control citrus pests in Northern Australia.


The colors of this meat ant specimen photographed by April Nobile (Copyright, 2000-2009. Licensing: Attribution-ShareAlike 3.0 Creative Commons License, downloaded from Wikimedia) have faded somewhat. Check out the gorgeous iridescent gaster of photographs of Iridomyrmex reburrus at

Now, I wonder if sprinkling cat food about will keep cats from sitting on my keyboard. 🙂

Georgia Ward-Fear, Gregory P. Brown and Richard Shine. (2010). Using a native predator (the meat ant, Iridomyrmex reburrus) to reduce the abundance of an invasive species (the cane toad, Bufo marinus) in tropical Australia
Journal of Applied Ecology, early view at journal website.

Ants and Passion Vines

Any ideas what the yellow dots are on this Passiflora leaf? Are insects involved?


It turns out that insects are part of the story, but probably not in the way that you might think.


This is one of the insect characters, the larva of a Heliconius butterfly. The female butterfly lays yellow eggs on passion vine plants, mostly in the tropics. The larvae consume a great deal of the plant before pupating.


In Arizona, another species can wipe out passion vines.


This is the larva of the gulf fritillary butterfly, Agraulis vanillae.

Researchers have shown the yellow spots on the leaves are made by the plants as a defense against these butterflies. When the butterflies lay eggs, they avoid laying on plants where another female has already deposited eggs. The yellow spots mimic eggs and thus fool the butterflies into going elsewhere.

That is only part of the story, however, because the yellow spots serve another purpose. Those are nectaries, glands that produce nectar. The free source of food attracts ants, which in turn defend the plant against any butterfly larvae that do hatch.

I have to say that at first glance the plant fooled me too. Did it fool you? Did you think those were insect eggs?

The theme today for Life Photo Meme at Adventures of a Free Range Urban Primate blog is “honor an invertebrate.” Why not ants that protect plants?