Nick Maclaren wrote or quoted:
In article , Tim Tyler wrote:

No, it doesn't. But, as far as every reference that I have seen has
said, 'farming' ants are either absent from the UK or EXTREMELY rare,
and even ones that actively 'herd' aphids are not common.

You've presented no evidence to that effect, that I've seen.

I am pretty sure that you have responded to posts of mine where I
gave it in the past, so I think that you have forgotten.

I certainly don't remember this - and visiting Google groups didn't
seem to help.

I have posted at least the following:

I have observed black ants cohabiting with ladybird larvae on
the same aphid patch.

I have done a crude (but fairly reliable) analysis of aphid
populations on some plants (mainly broad beans) in my garden
and elsewhere, and have found evidence that the populations
were being spready by rain and adult aphids but not ants.

I have searched the net and some other places for evidence of
the claims that ants cause or enhance aphid infestations, and
found effectively damn-all.

I know that aphid infestations are a major agricultural problem,
and I knew people working on defences, but not one was even
considering attacking the ants. This indicates that they knew
it was an irrelevance.

Others say:

``Management of ants is a key component of aphid management [...]''

- http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7404.html

....and...

``Using covers such as horticultural fleece can give good protection
against aphids and the viruses they transmit. Some ants "farm" aphids
for their honeydew that they produce. This means that they move the
pests around a plant to new pastures". If a tree is badly infested with
ants and aphids, a band of fruit tree grease, or a purchased 'grease
band' painted round the trunk stops the ants climbing up the tree.''

- http://www.myerscough.ac.uk/arboricu...b%20p age.pdf

....and...

``Apply grease bands or barrier glue to stakes and trunks. Keep in place
until late April. Can be reapplied in early summer to control ants,
which encourage aphids.''

- http://www.crown-nursery.co.uk/organictips.html

The percieved relationship is widespread enough to appear in
UK Organic association factsheets and in advice given by the
Royal Horticultural Society - I think it's quite reasonable
to think gardeners with aphid problems often look to their ants.

Also, it's a common sales pitch for ant killer sellers to point out
that ants protect and cultivate aphids.

I think you may be under-estimating the attention which
gardeners with aphid problems give to ants.

I've witnessed phenomena which I can only explain in terms of ant
protection of aphids:

For example last year my bronze fennel was attacked in the autumn by
aphids at ground level. The strange thing was, that the aphids were all
protected by a 4cm high wall of dirt, close up against the fennel stem.
I regularly knocked this off with a stick - and it was regularly rebuilt.
The plant was about four feet from two ants nests. The only conclusion I
regard as plausible is that the ants were responsible for building the
protective wall around the aphid infestation.

Ah! Yes, I will accept that as evidence. I have never seen it, in
my garden or any other, but I have heard of it. Are you claiming
that most (or even the most common) ants will build such walls?
If so, why are they so rarely reported?

I have no reason to think the ants in my garden (Bristol) are particularly
special.

I also found this description of similar ant behaviour:

``This genus of ants is known to tend aphids by “milking” them for
honeydew and therefore will attack the natural enemies of aphids.
Oftentimes they will take chewed up plant fibers and build a shed or
wall around the aphids to protect them from natural enemies and from
rain.''

- http://www.butterflies.org/news.cfm?newsID=10

I can make no claim about how widespread this behaviour is -
since I've only seen a few reports of it.

I've not seen ants attacking other plants with aphids in this way -
I conjecture that fennel is unusual in the extent to which it places
a carbohydrate rich food store at an accessible location at ground level.

Both my fennel and my ants survived the winter. I'll try to photograph
the behaviour - if it occurs again later this year.
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