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axyridis)</div> <div>=A0</div> <div>"
Randy Lauff wrote:
> Multicoloured Asian Ladybird Beetles (Harmonia axyridis)
>
>
>
> "They don't seem to do any obvious harm in the house."
>
> "Some of them get inside and when I'm there I dutifully collect them
> and release them in the greenhouse where I hope they can put a dent in
> the whitefly population..."
>
>
>
> Harm in the house...no...dent in the whitefly population, perhaps.
> Cause a catastophic decline in our native species' numbers...isn't
> this one of the foreign culprits that could be responsible?
>
Hi Randy & All, Oct 22, 2007
So far as I am aware, the notion that introduced Coccinellids were
responsible for the decline in native Coccinellids is unproven. My
sublimital impression drawn from observing or collecting beetles over a
period of 47 years is that natives, never abundant in my memory,
declined before the introduced became numerous. Aphids in good years
used to be abundant. Now, aphids in good years are still abundant.
The rather large land-use changes that took place during this period
include, loss of hedgerows and stone fences as fields were enlarged,
loss of headlands as tractors replaced horses, replacement of semi-wild
pastures by plowed and seeded pastures (this implies loss of rotting
stumps, brush piles and a host of pasture weeds including woody
perennials), replacement of wooden sheds and wooden barns having stone
foundations/blocks and usually earth below with less hospitable farm
buildings on concrete floors, invasion of forest, stream and farmland by
town folk, often with just-so sprayed lawns, sprayed gardens, lights and
bug zappers, introduction of broad spectrum insecticides which for some
years were over-used, control of field-edge and roadside weeds using
herbicide sprays, replacement of mowing natural meadows in late summer
followed by 2 months pasture by pasturing all summer and better control
of potential prey and weeds (both potential supports for prey and
sources of pollen or nectar) in agricultural crops and progressive
de-watering of landscapes as highways were widened and suburbs extended.
The rural landscape in 1940 had more in common with the 1890
landscape than with the 1990 landscape and with change there are bound
to be winners and losers.
>
>
> When they're in such large, accessible numbers, I'd take the
> opportunity to destroy them. When I look at the choice between my
> garden and nature as a whole, nature wins. And yes, I remove
> earthworms from my garden, too. And I have a wonderful garden. There
> is no need for for foreign species assistance in gardening, not at the
> risk of the loss of natives.
>
If you wish to let nature win in your garden should you not just
leave it alone and let Spruce trees and Alder bushes take over ?
Gitting rid of the effects of earthworms implies more than evicting
them. Depending on the profile there could be primary biopores made by
earthworms and secondary associated biopores down to 3 metres so it
could take some time.
Introduced plants and animals are also part of nature. That passage
from The Ancient Mariner I think says it best; 'He prayeth best, who
loveth best All things both great and small;'.
Yours truly, Dave Webster, Kentville
>
> Randy
> _________________________________
> RF Lauff
> Way in the boonies of
> Antigonish County, NS.
>
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