Annual

Definition

Completing an entire life cycle—from egg or birth through reproduction to death—within a single year or growing season. In arthropods, annual life histories are common in temperate and seasonal environments where populations persist through unfavorable periods as eggs, diapausing larvae, or adults. The term contrasts with biennial (two-year cycle) and perennial (multi-year, iteroparous) strategies. Annual species often show rapid development, high fecundity, and little or no parental care.

Etymology

From Latin 'annus', year.

Example

The periodical cicada Magicicada septendecim is not annual despite its common name; true annual cicadas such as Neotibicen canicularis emerge every summer in temperate North America, with each generation living less than one year as adults.

Synonyms

• monocarpic (when applied to semelparous organisms)

Related Terms

• Biennial
• Perennial
• Univoltine
• multivoltine
• Semelparity
• iteroparity
• Phenology
• Diapause

Usage Notes

In entomology, 'annual' describes life-cycle duration, not necessarily emergence every calendar year; some annual species may have staggered cohorts. Do not confuse with 'univoltine' (one generation per year), which describes voltinism rather than individual lifespan—an annual species can be multivoltine if generations overlap rapidly in favorable climates. The adjective form is standard; 'annuals' as a noun usually refers to plants in gardening contexts.