Menestor is known only through citations by later authors, primarily Theophrastus. No biographical details are recorded. His dating to the 4th–3rd centuries BCE is inferred from his citation by Theophrastus. An unconfirmed later tradition refers to him as Menestor of Sybaris.

No independent works survive. His ideas are preserved fragmentarily through testimonia in Theophrastus's Historia Plantarum and De Causis Plantarum.

Menestor contributed to pre-Aristotelian natural philosophy, particularly botany. Theophrastus reports that Menestor classified plants as "warm" or "cold" to explain phenomena like evergreen and deciduous behavior, linking these qualities to environmental adaptation. This represents an early systematic attempt at causal biological explanation using elemental qualities, placing him within the Pre-Socratic tradition of natural inquiry.