Symbolism, Imagery, Allegory
For most people, snakes are pretty scary. They're like slithering tails with eyes and they freak out even the manliest of men (case in point: Indiana Jones and Samuel L. Jackson).
What our lady Delia has is a snake phobia—she shakes, screams and nearly faints when the scaly beasts appear.
So when Sykes's bring a rattler home, she says:
Naw, now Syke, don't keep dat thing 'roun' heah tuh skeer me tuh death. [...] Thass de biggest snake Ah evah did see. Kill 'im Syke, please. (67)
The snake itself is a symbol of Sykes and the venom he spits at Delia in the form of verbal, psychological and physical abuse. Keeping him around the house is just as dangerous as a venomous snake.
When he brings home a snake, he goes too far and Delia kicks Sykes out once and for all:
Ah hates you tuh de same degree dat Ah useter love yuh. (79)
In a surprise twist of fate, the snake ends up biting and killing Sykes and saves Delia from an awful marriage. With this, Hurston seems to be warning that one's own evil will one day come back around to bite you.