Low butterfly numbers, not in MI

[Robert Kriegel]

I just returned from a weekend sampling trip in the eastern half of
Michigan's Upper Peninsula.  Butterfly numbers in the area did not appear
low.  The larger fritillaries in particular were very common.  I did see
three adult monarchs during the trip.  Butterfly numbers have also been
fine this summer in a wet meadow at my home in Bath, MI (just north of
Lansing).  Climatologically speaking, this has been a very strange year in
Michigan.  Degree day accumulations (base 50F) are currently running 1.5 to
2.5 weeks ahead of normal, depending on where you are in the state.  This
means that it can be VERY difficult to predict phenological events, such as
peak flight time for a particular species.  Apparent phenological
relationships among species (e.g., two species that normally fly at the
same time, or using first flowering of a plant as an indicator) can also
break down under these conditions.  

I wonder if some of the discussion on this list about low butterfly numbers
this season could be a result of these shifts in phenology?  For example,
given the degree day figures alone I would expect Michigan fourth of July
butterfly counts (both numbers and diversity) for 1997 and 1998 to be very
different indeed.

Bob Kriegel  <kriegelr at pilot.msu.edu>
Michigan State University