A point that has not been addressed on this thread that I have personal 
experience with is the break down of chemicals in the soil due to 
environmental conditions from one year to another.  My experience has been 
with potato herbicide residues in grain.  I think it could be safe to 
extrapolate to imidicloprid.  I have seen grain crops ruined by herbicide 
residues from potatoes.  The same soil types the same doses of herbicide. 
The only variable being the weather.  I have seen this happen repeatedly 
over the past thirty years.  Damage ranging from none one year to nearly 
total wipeouts another year.
If the same thing happens with Imid then that at least could be the 
explanation for the isolated bee kills.  As widely as it is used in my area 
there would not be any bees left if it carried over as bad as it has in some 
other areas.
Sometimes this damage is in patches associated with different soil types or 
soil PH.  When conditions are dry we see the most carry over.  These factors 
are uncontrollable.  If the extrapolation to imid is correct then parts of a 
corn field could be toxic to a hive of bees foraging on it while the rest of 
the field would be fine.  Bee hives from the same yard could be affected 
differently.
Dave
South East Idaho 

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