Canada's PMRA (Pest Management Regulatory Agency) cooperated with EPA in the 
registration of clothianidin.  Free trade agreements make both countries 
agree on pesticide registrations.   This is from the PMRA's factsheet on it:

Clothianidin was determined to be highly toxic to the honey bee, Apis 
mellifera, on an
acute oral basis with a LD 50 of 0.00368 µg/bee. The transformation products 
TMG,
MNG, and TZMU were determined to be of relatively lower toxicity to the bee, 
with an
acute oral LD 50 of > 152 µg/bee, > 153 µg/bee, > 113 µg/bee, respectively. 
The
transformation product TZNG was determined to be of moderate toxicity to the 
bee, with
a LD50 of 3.95 µg/bee. Field or semi-field studies conducted in Sweden, the
United Kingdom, France and Germany as well as in Ontario (Canada) and 
Minnesota
(United States) indicated that there were no significant impacts on honey 
bees compared
with the controls. All of the field/semi-field studies, however, were found 
to be deficient
in design and conduct of the studies and were, therefore, considered as 
supplemental
information only. Furthermore, the results of most of these studies 
indicated that residues
of clothianidin, when used as a canola (rapeseed) seed treatment 
insecticide, were
expressed in pollen and nectar of the crop plants (or collected from 
foraging bees). While
these residues are not likely to cause acute mortality or other short-term 
effects, questions
remain about the possibility of long-term effects on honey bee colonies.   A 
chronic,
multigeneration field study has been requested to clarify this risk.

This factsheet was from 2004.  Perhaps Dave Fischer could direct us to the 
field study.

Regards
Stan

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