Monarch/Milkweed question

Anne Kilmer viceroy at gate.net
Sun Oct 22 14:26:46 EDT 2000


We did not invent systemic insecticides. A plant that is chewed on will
whomp up its own potent poisons, sending them to one leaf, many leaves
or the whole patch as is needed. 
Therefore an oak or mahogany that has been defoliated will refurbish
itself with leaves too nasty for the leps to eat. 
Milkweeds will do this as well, on a smaller scale. 
Our disinclination to eat fruits and veg that have been bug-bitten is
based on a knowledge (practically a race memory) that the plant gets
nasty-tasting when it's been chewed on. 
There are exceptions, of course. All the best-tasting Surinam cherries
have maggots in them. 
But plants do not ordinarily rush sugar into invaded fruits. I wonder
how the fly persuades it ... 
Anyway, a passel of fresh young juicy milkweeds might invite an
egg-laying monarch. However, the lack of toxins would also mean that the
caterpillars were not protected from predators. It's all a balancing
act. 
You will have noticed that a larger monarch larva will partially cut the
stem of its leaf, and then feed? That reduces the amount of poison the
plant can put in the leaf. 
Tampa also spent the summer under drought conditions. This, too, will
concentrate toxins in the tough old leaves, and reduce the production of
tender, juicy new growth. 
Hope this helps
Anne Kilmer
South Florida

John MacGregor wrote:
> 
> > Your milkweeds may be excessively toxic, after their experience of last
> > year
> 
> Ann,
> 
> Am I missing something?  What would make milkweeds "excessively toxic, after
> their experience of last year"?  What experience?  Please, do, explain.
> 
> John MacGregor
> jonivy at earthlink.net

 
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