In 1997, she stole the identity of a retired teacher, Natalie French, so she could assume the role of a substitute biology teacher in Sunnydale High School by killing Dr. Gregory, the former biology teacher. Apart from every other boy in school, she seduced Blayne Moll, who was first to help her make model egg sacks for the Science fair. However, the She-Mantis drugged him and locked him in her basement where she kept him in a cage and began forcibly mating with him. She then targeted Xander Harris and invited him to her home, giving him a spiked martini before dragging him in the cage along with Blayne. She then attempted to mate with him in her mantis form but was then killed when Buffy Summers came to the rescue and hacked her to death with a machete. Xander then took the machete and used it to hack up the Mantis' eggs.
The She-Mantis could rotate her head 180 degrees and release pheromones to attract males, making them smitten by her very presense. The She-Mantis was also sensitive to bug spray and bat sonar. She mated at least once and was able to produce eggs most of which were destroyed except for a small clutch in a teacher's closet in her classroom, Science 109.
The She-Mantis used her powerful to devour human heads clean off her victim during mating, though the victim must be a virgin, presumably as her own preference. In her human form, she also ate live crickets which she placed inside a piece of bread.
Her method of reproduction was extremely similar to the sirens of Greek myth, Celtic sea maidens and similar temptresses of many ancient myths who welcomed their would be suitors with the most horrible forms of death, as researched by Ferris Carlyle who encountered one such beast though he was driven mad by the experience.