Beetas are supposed to attack dupes as they approach their hive. There is even an achievement for harvesting a hive without getting stung. But the achievement is trivial when the beetas ignore dupes. And i`m not talking about beetas that are sleeping in CO2. Those that fly around just ignore the dupes walking next to them.
Enable harvesting of a beeta hive and make sure there`s no CO2 around and a dupe can reach it.