Butterflies of
North America
Tiger
Swallowtail
Papilio glaucus
LINNAEUS, 1758
Family -
PAPILIONIDAE
subfamily -
PAPILIONINAE
Tribe
- PAPILIONINI
Papilio glaucus, Tennessee, USA ©
Ken Childs
Introduction
Papilio is the Latin word for
"butterfly". Back in the 18th century when Linnaeus created the
System Naturae, it was used as the genus name for every known
species of butterfly in the world. Since those early days
taxonomists have slowly unravelled the relationships between
different creatures, with the result that only about 215 of the
17,600 currently known butterfly species on Earth are retained in
the original genus Papilio.
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 glaucus is one of several
species which share the "tiger" pattern of black stripes on a
cream background. Only the males have the tiger pattern - females
are plain chocolate brown on both wing surfaces. They have a
series of submarginal cream coloured crescents on both wings, and
on the hindwings also have a series of post-median blue crescents,
and red anal and apical spots.
Four of the
remaining "tiger" swallowtails - canadensis,
appachaliensis,
alexiares and rutulus were
once considered to be subspecies of glaucus,
but are now recognised as true species.
P. glaucus is restricted to the
central and eastern states of the USA.
Habitats
This species is
found in open deciduous woodland, at altitudes between sea level
and about 1000m.
Lifecycle
The eggs are
greenish-yellow, speckled with brown. They are laid singly on
leaves of the foodplants which include
Prunus,
Crataegus, Malus ( Rosaceae
), Populus ( Salicaceae ),
Acer ( Aceracaea ), Tilia ( Tiliaceae ), Carpinus,
Alnus ( Betulaceae ),
Liriodendron ( Magnoliaceae ) and
various other trees and shrubs.
The
caterpillars when small are dark brown above, greyish below, and
are marked with a white dorsal saddle. When at rest on the
upperside of leaves they greatly resemble a bird dropping.
When fully
frown the caterpillars are plump, mid-green in colour, and have
a series of small blue dorsal and mid-dorsal spots. On the 3rd
thoracic segment there is a pair of yellowish ocelli, each with
a black "iris" and a central white "reflection" mark. If the
caterpillar is molested it hunches up, causing the ocelli to
expand and take on a threatening appearance which probably has
the effect of deterring avian and mammalian predators. If
molested further, the larva produces from behind it's head an
eversible fleshy orange forked structure called an osmaterium,
which
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.
The chrysalis
is light brown, mottled with olive or black, with a brown
lateral stripe and a pale dorsal stripe. It is attached by the
cremaster and a silken girdle to a woody stem, tree trunk, or to
broken twigs or dead leaves on the ground. The pupae hibernate
overwinter.
Adult behaviour
Males patrol
back and forth along roadsides and woodland rides in search of
females, and in hot weather aggregate in groups of up to 20 to
imbibe mineralised moisture from damp ground. They also feed at
carrion and dung. Both sexes nectar at
Lantana and many other wild flowers.
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