The "bees" are not possessive, so according to my editor boss, there should be no apostrophe. OH, but hang on....read this:

Apostrophes are sometimes used to make acronyms or other abbreviations plural (another matter of a local house style). My preference: don't use apostrophes to make abbreviations plural — not "They took their SAT's," but "They took their SATs." The only exception is when having no apostrophe might be confusing: "Two As" is ambiguous (it might be read as the word as); make it "Two A's." Never use apostrophes as single quotation marks to set off words or phrases (unless you need a quotation within a quotation).

Using an apostrophe to refer to a decade — the 1960's versus the 1960s — is another matter of house style; again, journalists tend to use the apostrophe, and most other publishers don't. I prefer to omit it: refer to the 1960s or the '60s (the apostrophe indicates that "19" has been omitted), not the 1960's or (worse) the '60's.