Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Thursday, March 01, 2012

Carrington Falls spectacular and spectacular tiny Aphids

You may recall that I mentioned yesterday, the high rainfall figures I had recorded in February. So I figured today would be a good day to check out Carrington Falls - with all that rain now running down the local creeks and rivers.

I know the Upper Kangaroo River can and does get much higher than it was today. But there was still a great flow in the river today. Put another way, there were no rocks visible in the river bed, for Damselflies to perch on, as they are prone to want to do on a normal summer's day.

The Upper Kangaroo River has been known to rise over the Bridge, forcing the road to be closed. Today there was no problem with the Bridge. But the river was certainly "high". When I crossed the Bridge, I knew I was going to see a pretty spectacular flow, at the Falls.
Looking into the Maelstrom at the base of Carrington Falls
1 March 2012
While my use of the term Maelstrom might not be technically correct, (as it is NOT a whirlpool or vortex),
Having grown up reading Edgar Allen Poe, I claim it is a defensible use of the term.

As a result of that reading (albeit a long time ago) the mental image I carry with me is of water disappearing down into a deep pit. That fits here, at Carrington Falls.
The impression is accentuated at this particularly steep lookout, as one wants to hang onto the metal barrier, to peer straight down into the Gorge, and then watch in awe, as the water crashes and splashes in all directions, at the foot of the Falls. The roar of the waterfall is also ovewhelming.

As Wikipedia says: "the word "Maelstrom" appears in diverse contexts metaphorically to make reference to different subjects or objects that suggest great chaotic or sinister forces. The word maelstrom is used to denote powerful, inescapable destructive forces." 

No argument there, from me.
Tall Frame view of Carrington Falls

The main part of Carrington Falls
1 March 2012
Zoomed image showing the river 
surging to the top of Carrington Falls.
Note the rich tannin-stained water
which come from the Button Grass swamps upriver.


Having left Carrington Falls lookout, I walked back to the carpark, 
and as I did I noticed 
a cluster of tiny bright yellow Aphids on a stem of a Milk Vine.

Apparently they are "Milkweed Aphids" - Aphis nerii
I am always impressed when I find
insects which have sorted out plant relationships
in the same way that the Botanists have.
Aphis nerii - the Oleander Aphid or Milk Weed Aphid
feeding on a related plant - the Milk Vine.
Marsdenia rostrata.
The Nerium, or Oleander, after which this Aphid is named,
is a member of the Apocynaceae family. 
So is this vine - although it looks 
very different from the garden Oleander.

Aphids are tiny members of Order Hemiptera - Bugs
Bugs suck liquid food through tube-like mouthparts. 
Most are plant-feeding, sucking the sap of their host plants.
In this case, the Milk Vine has a milky latex sap.
Many plants in this family do (hence the name).
Many of these Apocynaceae plants 
are used to produce medicinal drugs,
but some of them are toxic to animals 
(including humans) 
if ingested.
Latex sap of the Marsdenia rostrata gives it the name "Milk Vine"
You may recall a similar discussion 
which I found a few weeks ago. 
They were feeding on a Narrow-leaved Cotton Bush
That plant is known as a "Milk Weed" 
(one of many related plants) 
and it is also in the same family Apocynaceae

As I indicated above, it always impresses me 
when our insects are better Botanists than I am.
These tiny Insects instinctively know
which plants they like, 
without looking up plant references on the Computer,
(as I have to do).

And I am especially impressed if the plant of their choice 
happens to be poisonous. 
That indicates to me that they have apparently 
developed an immunity to the plant's toxins.

Is this another case in which the insects possess 
the ability to store the plant's toxins
and maybe use the toxins
to protect themselves from attack by predators?

I strongly suspect that the yellow colour of these Aphids
is a "warning signal" - to just that effect -
to protect the Aphids from other insects and or birds.
Aphis nerii - the Oleander Aphid or Milk Weed Aphid

Remember the Caterpillars of the Monarch Butterfly 
Can it be a coincidence that these Aphids have similar colours?
The Monarch Butterfly's Caterpillars feed on related plants
which are similarly toxic.
Is that a random chance? I doubt it.
These little Aphids were quite active, 
with individuals frequently standing almost upright 
while they seemingly drove their little 
tube-like mouthparts into the soft tissues of this plant.

You may have noticed in the earlier photos that 
they are all gathered on the fresh new growth of the plant
as that is where they can most easily penetrate the plant tissues
and suck the sap.

The things one can find out in the Bush!
Even when originally going out 
simply to catch a "Tourist Postcard" image.


mick said...

Interesting insects but definitely spectacular falls. 'Tourist postcard' photos are good! Hopefully I can show some next week. Some net connections are definitely better than others!

Joy Window said...

By coincidence I've just been reading the really interesting book "For love of insects" by Tom Eisner. He says that many insects that feed on milkweed and suchlike cut the veins of the leaves so that they don't have to deal with the toxic latex. Cutting the veins cuts off the supply of latex to the parts of the leaves they want to eat. Then they can munch away to their little heart's content. Isn't evolution wonderful?

Le Loup said...

Great images of the falls, thank you.

Denis Wilson said...

Thanks Mick, Joy and Keith.
While I remember, Keith the Spammers are sneaking through - about 6 a day, since I disabled the Comment Verification process. I am getting sick of them. I still get to delete them before they are published, it is just a bore that I have to. Clearly automatically generated mindless comments.
But generally, thanks, Mick, Joy and Keith for comments from real people.
It is a great waterfall. Not our biggest, but because the gorge is so tight, one can sit directly opposite it, and get much better photos than one can of Fitzroy Falls or Belmore Falls.
Joy, your comments about the insects disabling the flow of sap rings a bell. I have heard such a story before, but while it might apply to the Caterpillars, it cannot apply to these tiny Aphids. But interesting, none-the-less.
I shall see what more I can learn about Milk Vines and their sap.
Mick, you're apparently having Internet problems. Hope it gets fixed soon.