Re: ants again

From: Miriam English (
Date: Mon Oct 22 2001 - 21:41:12 MDT

Hi Spike,

I love to watch ants too, and have seen this before. When I was a kid we
had a large nest of meat-ants (dunno their proper name -- about half an
inch long with red body and black abdomen) near the house which we used as
a garbage disposal for all the things that the dog, the local wild birds,
and the fish didn't want or couldn't eat. This colony grew and grew. I used
to very carefully squat on the edge of the enormous mound and watch the
little critters for hours. It always amazed me that they never tried to
attack me.

One day I was walking down the long bush path to the house when I noticed a
trail of ants with exactly the qualities you mention. They had cleared a
highway in the undergrowth -- astonishing in itself. I followed the path
both ways -- to its source and its destination. The source was the
enormous, well-fed colony near the house. The destination was a spot some
hundred yards away (maybe less). Initially I thought they were migrating,
but I realised after the traffic had dwindled and eventually stopped that
the colony had split.

I have often wondered what determined which ants went to which colony. I
assume the move was triggered by the colony reaching critical mass and some
hormonal trigger causing the split. I wonder if the new queen was produced
before or after the migration. I don't think ants are as ummm antsy about
having more than one queen as bees or wasps are.

The complex behavior that ants are capable of in groups is quite
enthralling. I wonder how much analogy can be drawn between group behavior
in humans and in social insects. Craig Reynolds' classic flocking behavior
requires only 3 simple rules:
  - Separation: steer to avoid crowding local flockmates
  - Alignment: steer towards the average heading of local flockmates
  - Cohesion: steer to move toward the average position of local flockmates
We can see them at work in any crowd of people.
Ants have similar simple rules that govern apparently complex behavior.
Some work by Chris Langton has uncovered some of these. Craig Reynolds has
also worked on them.

If you like ants, you should see our bull-ants. They are the largest ants
in the world -- about an inch long. They have quite small colonies of less
than a thousand individuals I believe. There are smaller variants, about
3/4 of an inch, commonly called bulldog ants which are considerably more
ferocious than the larger ones. Bulldog ants will actually chase and jump
at you. All kinds of bull-ants have very painful stings. I have been stung
so many times I hardly get any reaction now apart from the initial pain and
later furious itch.

My 2 brothers once watched an army of bulldog ants surround and take a
termite mound in all-out war. Wish I had seen that. How the hell they
coordinate such maneuvers boggles the mind.

Happy ant-watching.

Best wishes,

         - Miriam

At 11:52 AM 22/10/2001, Spike Jones wrote:
>Today I witnessed something that is baffling the hell outta
>me. I have been an ant watcher for many years but I saw
>something today that I have never seen before.
>When one sees an ant trail, one always sees ants going
>both directions, nearly balanced, so that the net ant flux is
>approximately zero. Those who have been to my house
>know that I have an integral garden {because it is a
>raised area with a curved wall shaped like an integral
>sign} and an eliptical grass area, golden ratio ellipse.
>I saw an ant trail going from the integral garden to
>the ellipse *with a definite direction*. The ant trail
>had a very high one way flux, perhaps as high as 10
>ants per second, with only an occasional wanderer going
>back the other way. This was an ant colony that had
>suddenly just decided to *move* somewhere.
>I saw no obvious food source in the grassy ellipse.
>I searched but found no reason why the integral garden
>had suddenly become the place not to be. No sprinklers
>had come on, no chemicals were released. I noticed that
>many of the ants were carrying eggs. None of the few
>backtrackers had eggs, whereas about a third of the forward
>movers had eggs.
>Another thing about ant lines is that they do not change
>suddenly. This one did. Over a period of about 15
>minutes, the ant flux declined from about 10 per second
>to nearly zero: the backtrackers remained constant while
>the forward goers quickly dropped to about the same as
>the backtrackers.
>This was a clear case of a colony moving somewhere,
>but what I dont understand is why, and why now exactly,
>and how do they signal everybody to grab an egg and
>walk this way?
>Can anyone suggest how to make an instrument which
>would watch an ant trail and measure flux? I need something
>I can connect to a computer so it can watch all the time
>while I go to work. spike

To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.
Virtual Reality Association

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