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Bogong moths -

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Bogong moths

Bogong moths exist as larvae in much of eastern Australia. When they hatch they fly to the
mountains and hide between rocks. They fly vast distance such as across Bass Straight. And they fly
in huge numbers, being food for many animals, including some people. They are attracted by lights
and can cause damage to machinery and infrastructure. Moths are high in arsenic but its source is
uncertain.

Transcript

Robyn Williams: If you're feeling frustrated with Canberra, with all the procrastinating and
hand-waving, just remember it's not long before the Bogong moths turn up to help. Millions of moths
descend on Parliament House and other parts of Australia to remind us who's really in control.
Susan Lawler, who is a geneticist at Albury-Wodonga, is studying the moths and their larvae.

Susan Lawler: It exists as a cutworm larvae throughout the eastern coast of Australia, from
Queensland all the way down to southern Victoria and all the way across to Adelaide. These little
things are agricultural pests in pastures. When they hatch into a moth they then fly to the
mountains where they hide between the crevices of rocks, and no one is really very sure why. It may
be that they're having mating flights or something up there. The certainly don't do a lot of
eating, they do a little bit of drinking while they're there, they fly at dusk and dawn, and
they're very yummy.

Robyn Williams: Very yummy, we'll come to that, but they also travel very big distances, and one
wonders why.

Susan Lawler: Yes, one wonders why indeed. In fact, doing the research on the ecology of 'why' is
something many of us would like to do but it's very difficult to do even the simplest research on
these animals because their migration routes change year to year, the amount that show up in the
mountains changes year to year. We recently found a population down in Tasmania coming across on
the boat, on the ferry from Tasmania to Melbourne. In the morning when we woke up they were all
fluttering against our porthole window, and when we went up on deck we found they were all over the
boat, settling into crevices as if they were on top of the mountain.

Robyn Williams: So they cross the sea as well.

Susan Lawler: They fly across Bass Strait twice a year.

Robyn Williams: This tiny moth...well, moths are tiny, all of them, and crossing great big oceans
like that would seem to be completely counterintuitive. Are they in very, very big numbers, these
clouds of them?

Susan Lawler: Yes. I believe they used to be in even greater numbers than they are now, millions
and millions of them, and they actually support an entire ecosystem on top of the Alps; the ravens
eat them, the pygmy possums eat them, the antechinus eat them, and Aboriginal people used to eat
them and still do when they get a chance. So they are a very important source of protein and fat
for the animals on top of the Alps.

Robyn Williams: You say they're yummy, so you must have eaten them yourself.

Susan Lawler: Well, no, I'm only told they're yummy, I haven't eaten one myself. I understand the
proper way to cook them is so that the wings in fact burn off, and you don't want to eat the wings
because they get stuck in your throat, but the body of the adult is very high in protein and fat
and is sort of a nutty flavour, I'm told.

Robyn Williams: They put them in bread, and if they don't take the wings off you can see the wings
there on the crust.

Susan Lawler: Oh ew! I wouldn't want to eat the wings. There are lots of recipes of bush tucker for
Bogong moths. One of them is called pop-moth, popcorn and Bogong moths.

Robyn Williams: Why do they go to parliament?

Susan Lawler: They are flying from somewhere to somewhere, and the lights of Parliament House
attract them. My PhD student was trying to collect them at Parliament House just last year and a
security guard objected to her picking these things off the window, and when she told them what she
was doing, he didn't leave her and it was a very awkward evening for her.

Robyn Williams: So it's not just love of Kevin Rudd or John Howard or anything like that.

Susan Lawler: No, no. If we could just turn the lights off in our nation's capital they would fly
right by.

Robyn Williams: Interesting. What about this problem of poison because if they've been eaten for so
long as a standard part of both human and animal diet, what about this strange ingredient you've
discovered?

Susan Lawler: Well, it wasn't me that discovered it, a man named Ken Green who works for the NSW
parks service noticed that there was dead grass in front of one of the caves that they hide in over
the summer, and in trying to figure out why the grass was dying in front of this cave, he analysed
the soil, the grass and the moths and found out that the moths had very high levels of arsenic.
What we don't know yet is where the arsenic comes from, why the moths are high in arsenic. Ken has
analysed ravens and pygmy possums and found that animals that eat moths are also high in arsenic.
We don't know if this is new, we don't know how dangerous it is, and the thing that my student in
fact is trying to research is where that arsenic comes from.

There are a number of possible sources. The smoke stacks of our cities put an enormous amount of
arsenic into the atmosphere, and it may be that during their 1,000-kilometre journey they're
picking it up on their wings. It may be that when they are larvae in the soil they're being sprayed
by agricultural chemicals and that there's arsenic being introduced to them in that way. And it is
also true that Australian soil is naturally high in arsenic, so it may be that this is a natural
background level that we never noticed before.

Robyn Williams: Would it be possible to go to a museum which has a collection of Bogong moths and
see whether in the old days there was less arsenic?

Susan Lawler: That's a really good question. We're analysing single moths for the first time, Ken
Green put 50 or 60 moths together and smooshed them up and analysed the arsenic, because each moth
is rather small, so our technique will give us a baseline of what the moth levels of arsenic are
from different mountains across Australia. And we're also looking at different chemicals because
arsenic comes linked to companion chemicals like lead or caesium or magnesium, and each of those
companion chemicals can give you a clue as to the original source. So yes, that's an interesting
idea and I think we'd like to do that someday.

Robyn Williams: In the meantime I suppose we'd better stop eating moths really, Aboriginal people,
ourselves and so on?

Susan Lawler: Well, we have tried very hard not to frighten people overly. It is true that if you
were going up and spending the summer on the Alps and eating nothing but moths, as was done in the
olden days, that would probably not be advised, but we're not yet ready to say that the levels of
arsenic are at a toxic level for humans, although that is one of the questions that we're trying to
learn about.

Robyn Williams: Going back to those sheer numbers, of course legendary, flying over Australia, and
it's the nature of large populations to breed like that so that some survive because, as you say,
if you're the dinner of so many different creatures there's safety in numbers. But they themselves,
to get those numbers, must be eating something else. What's the secret of their amazing population?

Susan Lawler: Well, they eat as caterpillars and they eat the roots of grasses. So they're grazers,
they just eat plants, and that makes sense, most of the animals that are really common on our
planet are grazers; look at cows.

Robyn Williams: So when will you know, when can I come back to check with your student? She's in
Albury-Wodonga?

Susan Lawler: Yes, Pettina Love is my PhD student in Albury-Wodonga. If you want to learn about the
project she says to Google 'love moth' and it will come up as one of the top ten pages.

Robyn Williams: 'Love moth'?

Susan Lawler: Yes, her surname is Love and she works on moths.

Robyn Williams: Oh, I see, although I can imagine that if you Google something like that you could
find yourself compromised with all sorts of strange sites.

Susan Lawler: I assure you, you will be fine. We've actually got laboratory analyses coming back in
the next couple of weeks, and with a few manipulations through the computer and some head
scratching we'll know in a few months what we think is going on.

Robyn Williams: And when they find out, we'll let you know. Sue Lawler at the La Trobe campus in
Albury-Wodonga where she's a senior lecturer in genetics. So don't scoff too many Bogongs this
year. They take off in a few weeks in spring.