Brimstone Butterfly

Flight period type: Single brood (extended)

The Brimstone Butterfly is one of the earliest butterflies to appear in the year in Abingdon, often seen on the first warm days of late winter. Its strong yellow colour and purposeful flight make it a distinctive early-season presence.

This page summarises how the species appears in the records: the structure of its flight period across the year.

Flight Period

Brimstone shows a single, extended flight period centred on early spring.

Records begin in February, rising through March to a peak in early spring (March–April). Activity then declines gradually through May and June.

After a summer gap, a small number of records appear again in early autumn.

The overall pattern is that of a single brood with an extended seasonal presence, including a late-season tail.

Interpretation

The Brimstone’s flight pattern reflects its distinctive life cycle, particularly its ability to overwinter as an adult.

The early appearance in February and rapid rise into March and April correspond to overwintered adults becoming active as temperatures rise. These individuals dominate the spring peak.

Following this, activity declines through late spring and early summer as the first generation completes its life cycle.

The small number of records later in the year likely represent newly emerged individuals from this brood. These butterflies may then persist into autumn before entering hibernation.

The result is a pattern that appears “extended” despite being a single brood:

Early activity driven by overwintered adults
Peak in spring during breeding activity
Late-season tail from newly emerged individuals

Overall, the pattern reflects a single brood species with a prolonged period of adult activity due to overwintering behaviour.

Summary

Aspect	Classification
Flight period	Single brood (extended)

## Data The data underlying these charts can be downloaded below: - [Flight period data (presence and totals)](/wildlife/reports/Year-In-The-Life/year_in_the_life_brimstone_butterfly_abingdon_butterfly_flight_period.xlsx)

Notes

These patterns are derived from long-term personal field records and should be read as descriptions of observed activity rather than complete biological accounts.

For butterfly species, seasonal patterns reflect the timing of adult flight periods rather than continuous presence. In species such as Brimstone, overwintering as an adult can extend the apparent flight period across multiple parts of the year.