tbf it probably works on most humans, they're probably pretty intimidated
I do find it weird that in a species where some of them have stingers, the ones in charge of defense are not in that group.
I think its more the first line of defense, they are not there to kill, they are there to basically state I don't want you here without provoking a lethal response from whoever is encroaching on them. It causes a lot less death of their males since they are known that they are not a threat, reducing the overall attrition of them over time and making life easier on the hive. The females with the stingers come out if something is a real threat, ie something messes with the hive or queen.
Honestly, kinda reminds me of British (and other non-militarized) police. Don't send guns to every problem as most can be solved without it and some are made worse by their presence.
