* βασίλισσα μέλισσα (vasilissa melissa): This is the most literal translation, using "βασίλισσα" (vasilissa) for queen and "μέλισσα" (melissa) for bee. It's perfectly understandable and commonly used.
* βασιλική μέλισσα (vasiliki melissa): This uses "βασιλική" (vasiliki), meaning "royal" or "queenly," which is more descriptive of the bee's status.
Both options are acceptable. The first is simpler and more direct, while the second is slightly more evocative.