ants and b'flys

[Anne Kilmer]

bstout at news-press.com wrote:

> Dear Ann <
> 
> Eavesdropping on your naturepotpourri chats. I am curious about a 
> beneficial relationship between bull ants and Miami blues. In my 
> experience with Gulf fritillaries and zebra longwings, their 
> caterpillars were wiped out by ants (carnivorous carpenters, I think) 
> attracted to my passionflower vines by the nectar nodules the plant uses 
> for that express purpose.
> 
> Thanking you in advance for any elucidation.
> Byron Stout
> Sr. Staff Writer
> The News-Press
> (239) 335-0494 (fax) 334-0708
> 2442 Dr. Martin Luther King Jr., Blvd
> Fort Myers FL 33901
> 

Yes, your experience is quite normal; ants do indeed gobble up 
caterpillars, invited to do so by the passionvines.

The story of the blue butterflies is quite different. It's hard to tell 
it without being a bit teleological, with references to Mother Nature 
and the Merry Little Breezes, but I'll do my best. (Scientists don't 
like to see the word "purpose" used when referring to a vine's 
characteristics and behavior. The vines I know are pretty smart.)

Here's the tale.
Just as some plants attract ants, with delicious nectars offered in 
extra-floral nectaries, so many of the blue butterfly larvae attract 
ants. They offer a liquor, certainly sweet and perhaps drugged ... a 
euphoric, a hallucinogen ... who knows. You'd have to ask the ants.
The ants, delighted by the nectar,  tend the caterpillars. They keep 
away predators, clean and polish the larvae, sometimes herd the larvae 
into their tree by day, and back into the nest by night, protect the 
pupae, and even, in a few cases, take the caterpillar into their nest 
and feed it on their own children. (Kids are a dime a dozen, after all, 
and a good slug of nectar is a treat).
Some blue butterflies, Britain's Large Blue, for instance, must have the 
tending of those ants. And the Large Blue was extirpated because its 
pastures were mowed rather than grazed; a different ant moved in and 
that ant, while it did indeed carry the caterpillar into its nest, 
butchered and ate it.
That Blue has been successfully re-established, I understand.
Incidentally, when the butterfly emerges from its pupa, down there in 
the dark, the ants don't recognize it as their old buddy, and it has to 
hustle for the surface while they try to grab it. It has a lot of 
break-away scales which give it a chance to get away.

Sometimes the plant and the butterfly and the ant all seem to get along 
just fine. Acacias often have extra-floral nectaries, and some 
ant-tended blues are found on acacias. It would be interesting to know 
whether the caterpillar's nibbling serves as a beneficial pruning for 
the plant. I would think so. As you know, we pinch out young growth to 
make a plant branch. That provides more sites where flowers and seeds 
can form.

Our little Blue, Cyclargus thomasi bethunebaker, is tended by a species 
of Camponotus, popularly called Carpenter ant or Bull ant. I don't know 
whether other Camponotus species will tend it. I don't know whether 
Technomyrmex albipes, the white-footed ant, will tend it. It's a 
generalist, and tends many kinds of insect.
I am sure, however, that fire ants would kill it, and that it is hanging 
out welcome signs and filling the air with sweet-scented attractants, 
poor naive fool that it is.
So gardeners hoping to tend a Miami Blue vine, aka Cardiospermum 
corindum, our native Balloon Vine, must take care that fire ants do not 
find it, but may treat the bull ants affectionately unless they see them 
actually chewing up and carrying off the larvae.
Apparently the caterpillar gets along ok without the ant, though. So you 
need not go hunting for carpenter ants and carry them into your garden.

I'd be interested to know whether there are carpenter ants in the colony 
Bob Parcelles has observed, and whether there are fire ants on Bahia 
Honda Key. I do know that bull ants will collect Amdro and kill out 
their colony. I watched them do this, in my very own utility room. 
Clearly they had failed to read the label on the bag, which was quite 
specific as to what ants should enjoy this treat. I was sorry, but not 
very. Not my fault, after all.

Hope this helps. ;-)
Anne Kilmer
Mayo, Ireland








 
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