Old World Swallowtail finds breeding grounds in Brussels

July 19, 2026

(Papilio machaon) has appeared twice in the city this summer — once at Laeken on July 15, again near Chapelle on June 27 — suggesting that breeding may now be underway in urban Brussels rather than merely passing through.

Females of this species stay close to their egg-laying plants, and the appearance of two individuals weeks apart in midsummer is a strong signal of established populations. Wild carrot on railway margins and other ruderal edges has become an anchor for the species here; warmer summers are steadily expanding the range of its host plants northward, opening ecological doors that were shut just a decade ago.

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