Other Common Names
Common yellow swallowtail
Explanation of Names
The various subspecies included here under the name Papilio machaon have been (and contunue to be) treated differently by different authors. The most commonly seen alternate classification would have the subspecies bairdii, dodi, oregonius, and pikei placed as subspecies of a distinct species Papilio bairdii, and the more boreal subspecies would be left under the species Papilio machaon. There are good reasons for doing this, but the majority of workers currently place them all under one species. There are also still some people who would prefer to see each name treated individually at species ranking, though this is not widely accepted practice. The result is that these butterflies may be listed under a number of different name combinations, depending upon the preferences of the individual author.
Range
Holarctic, with a very wide distribution in boreal and temperate Eurasia and in western North America.
Season
Northern populations are univoltine with the single adult flight mostly in June and July. Further south two or three broods may occur with the first flight in spring, mostly in April, May or June depending on the local climate. Perhaps flying in waves year-round in some parts of California.
Food
In North America, larval host plants are primarily in the genus Artemisia, with the more southern subspecies (including ssp. pikei) almost exclusively utilizing A. dracunculoides (Asteraceae). They will occasionally utilize Rue (genus Ruta) or certain Umbellifers (family Apiaceae) as alternate hosts, and can be reared on certain members of these families as well.
More boreal subspecies aliaska and hudsonianus have been recorded on other hosts, including Cnidium cnidiifolium, Ligusticum scoticum, and Zizia aptera in (Apiaceae) and, on Artemisia arctica and Petasites frigidus in (Asteraceae). All of these plants apparently have key chemical similarities to members of the family Rutaceae, which is probably an ancestral host family for a majority of the genus Papilio.
In Eurasia, Papilio machaon is recorded as utilizing members of the Apiaceae, and sometimes Rutaceae.
