I wonder if the ranger may have been thinking of one of the
Heliothis, a 'pest' of corn, cotton, tomatoes ...
Isobel.
On 17/1/19 at 10:54 AM, (David Rees) wrote:
>John
>
>I think your Park Ranger is a bit confused. This particular moth mainly
>breeds, inland, not on the coast - on the plains from northern Victoria to
>southern Qld. Don't know which plant 'corn' is Wheat or Maize. Maize is
>not grown much in Australia - mainly here and there as an irrigated summer
>crop, with a small amount of customary production in summer rainfall areas
>southern Qld. which mostly goes into Australian made cornflakes. Important
>thing is that it is a summer crop, i.e. the moths are tucked up (should be)
>in their caves when this stuff is growing. There are other moths that are
>bad on this, related very similar species but not the same.
>
>Lets look at wheat, its a winter crop in Australia and certainly NOT grown
>on the coast. The amount of pesticides put onto Australia's dryland wheat
>is low and not getting higher. Chemicals allowed these days are
>non-persistent in the environment. Herbicides are used, mainly for
>preparation and pre-crop emergence, the most popular one is Glyphosate.
>This use cuts down hugely on diesel used for heavy cultivation and reduces
>risk of soil blow as stubble can be left intact and the new crop drilled
>into it, with control of emergent weeds. Glyphosate breaks down quickly
>with contact with soil and does not accumulate in animals ( insects,
>mammals etc. etc).
>
>In the 'good old days' pesticides such as arsenic, DDT, etc were used to
>deal with catapillars that would accumulate in the environment and could
>act in the way your range said. Its just that individual you spoke to is a
>few decades out of date with his/her thinking.
>
>The main threat to this system is not agriculture, it is the effects of
>climate change that will bring more severe droughts and hot periods such as
>we are in right now. If there is no winter rain, there is no growth and
>therefore no food for caterpillars and therefore there are no moths to fly
>to the mountains, its pretty simple... Furthermore, higher summer
>temperatures mean that the temperature in the bogong caves will go up. this
>is also detrimental to moths survival as they will be more active and use
>up their fat reserves before they have chance to fly back to the breeding
>grounds in autumn. This system is finely tuned and climate change could
>cause it to collapse, quite quickly. We might be seeing that happen right
>now before our very eyes.
>
>David
>
>
>On Thu, Jan 17, 2019 at 7:00 AM John Harris <>
>wrote:
>
>>A sad postscript to the current thread about low numbers of Bogong moths
>>is that they breed on the coast often on farmland where corn etc is grown
>>and they absorb Agicultural chemicals. They carry these chemical residues
>>to the mountains where a Park Ranger told me that increasing bird deaths of
>>insectivorous species were attributed to ingesting hebicides, pesticides
>>etc. from eating the moths. Same must apply here in the ACT now I think
>>about it.....
>>
>>
>>
>
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