With regard to seasonal studies of bee nutrition/nutrient content, some
information is available in:  Grogan, D.E. and J.H. Hunt. 1984. Chymotrypsin-
like activity in the honeybee midgut: patterns in a three-year study.  J.
Apic. Res. 23:61-63.  We documented seasonal changes, correlations between
hives within years, and absence of correlation within hives between years.
We suggest that the patterns are affected by nutrition, most likely the
enzyme activity of ingested pollen.