Mexico, USA & Canada
Papilio rutulus, Sierra Nevada,
California, USA ©
Marijn van den Brink
Back in the 18th century when Linnaeus created the
System Naturae, the word Papilio was used as the genus name for every known
species of butterfly in the world. Since then much has been learnt
about the relationships between different species. Consequently
most have been reassigned to new genera, and only about 215 of the
17600 currently known species are retained in
There are 30
Papilio species in the Australian
region, 60 in the Oriental region, 40 in the Holarctic region, 54
in the Afrotropical region, and 31 in the Neotropical region ( the
latter figure includes 28 that have recently been transferred to
the genus Heraclides ). The 40
Holarctic species include 21 found in North America - excluding
those found south of Mexico, on Caribbean islands, and species
that have been transferred to Heraclides.
Papilio rutulus was originally
considered to be a subspecies of glaucus.
Females of glaucus however are
earthy brown in colour, with no trace of dark bands on the
upperside, whereas rutulus females
are identical in colour and pattern to the males.
P. rutulus is restricted to the
western states of the USA.
This species is
found in open woodland, at altitudes between 0-1500m.
The eggs are
greenish-yellow. They are laid singly on
either surface of the leaves of the foodplants which include
willows Salix and poplars Populus ( Salicaceae ), and
various other trees and shrubs.
caterpillars when small are dark brown, with grey prolegs, and
are marked with a white dorsal saddle. When at rest on the
upperside of leaves they greatly resemble a bird dropping.
grown the plump larva is mid-green in colour with small pale blue dorsal
and mid-dorsal spots, and a narrow cream band behind the thorax. On the 3rd
thoracic segment there is a pair of cream ocelli containing a
blue-centred black spot. If the
larva is molested it hunches up, causing the ocelli to
expand, giving the larva a threatening appearance which probably
deters avian and mammalian predators. If
molested further, the larva produces from behind it's head an
eversible fleshy orange forked structure called an osmaterium,
emits pungent chemicals.
Experiments with captive birds have demonstrated that the
chemicals are ineffective against them, but they are capable of
deterring ants, and predatory / parasitic wasps and flies.
is light brown mottled with olive, and has a brown
lateral stripe and a pale dorsal stripe. It is attached by the
cremaster and a silken girdle to a woody stem or tree trunk.
back and forth along roadsides and woodland rides in search of
females, and in hot weather aggregate in groups to
imbibe mineralised moisture from damp ground. They also feed at
carrion and dung. Both sexes visit a wide range of herbaceous
and bushy plants for nectar.