I took this achievement in the swamp section, when the mother (Marguerite) is hunting you. Find her and start shooting her with a shootgun, she will start spawning bees in front of her and the shotgun will kill, at the end, her and bees giving you the achievment. At least it worked for me, good luck.
P.S: Another easy method could be using the granade luncher in final phase of the mines where lots of micomutants (normal monsters) attacks you. Shoot them with the pistol to lower their HP then shoot with the grenade luncher (or the sticky bomb) and gg.