Record Low Monarch population expected in Mexico this winter.

[Paul Cherubini]

Monarch populations in the upper midwestern USA have been
much lower than normal late this summer.  Experienced observers 
have found only dozens of monarchs at traditional overnight clustering
sites that normally contain many hundreds or thousands of 
monarchs.  Thus it appears likely the overwintering
population of monarchs in Mexico this winter will be at
record low levels.

The Mid-summer population of monarch adults in the upper
midwest was only slightly to moderately lower than last
summer. The cause of the late adult population crash 
summer appears to be a high population of monarch egg and first 
instar larval predators such as ladybugs, ants, spiders, lacewings, 
etc.  Several observers including myself found very few large 
monarch caterpillars in July & August in Minnesota because the 
predation of monarch eggs and baby caterpillars was so high.  

The weak monarch migration this fall and record low overwintering
population in Mexico will undoubtedly lead to many frightening and 
worrisome "this could be the end" type monarch horror story articles
in the popular press. I predict some of the scientists authoring or quoted in 
the articles will not talk much about the natural biotic or abiotic factors
that could have led to the monarch population crash, but instead will try to 
link the crash to human disturbances of the environment such
as logging, urban sprawl, pesticide use, global warming, genetically
modified crops, etc.  Rant:  Nowadays it is fashionable and financially
rewarding to link the decline of butterflies to human disturbances as this leads 
to a greater level of public fear and worry and hence larger grants and 
donations for the conservation organizations.  

Paul Cherubini
Placerville, Calif.

 
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