August 2006
 
 
 
 
 

The Swallowtail Butterfly

Order               Family                   Genus and species

Lepidoptera          Papilionidae            Papilio glaucas

There are many genus and species of the swallowtail butterfly.  They come in many diverse
colors and are found in numerous parts of the world.  Although tropical regions of the world
are more suitable environments for these colorful insects, they also have adapted to many other
types of climates and surroundings.  There are more than 500 different types of swallowtail
butterflies in the world but there are only two which will be discussed here: 1.  The western
tiger swallowtail and 2. more specifically, the eastern tiger swallowtail, (pictured in the above
graphic.)  The swallowtails get their name from their hind wings which have tails at their lower
tips resembling the long tail feathers of swallows.

Above is a caterpillar which will soon transform into a beautiful anise swallowtail.  This species
is similar to others which will change into various forms of swallowtails. All swallowtails will go
through four life stages 1. egg,  2. larva (caterpillar), 3. pupa and 4. the adult butterfly.  This entire
process takes around six weeks.

Once hatched, caterpillars go through four transformations, called instars - before they pupate.
After each molt,  the caterpillar eats the old skin which is rich in nutrients.

The female will lay over 100 eggs during her lifetime.  These eggs will be laid during four laying
sessions and  are laid on  the upper surface of leaves, making a  convenient feeding ground for
the larva after the eggs hatch.  Caterpillars will feed on the leaves, avoiding the veins, almost
continually for  the next 30 days.  Silken pouches are  woven over the leaves and branches to
protect the fragile worms from birds and other predators.

Eggs hatch at different times, depending on the ambient temperature, humidity and on other
environmental conditions but usually hatch in around two weeks.  The caterpillar stage lasts
about one month before pupating, and the butterfly stage will last a little over three weeks.

In the graphic below,  the caterpillar goes into hibernation in a hard casing called a chrysalis.  The
chrysalis is the overwintering stage in the swallowtail's development, and protects the vulnerable
caterpillar until warmer weather allows it to break free to live its last few weeks as a butterfly. In
warmer climates, the pupal stage is much shorter.

After becoming butterflies, they fly from flower to flower....hovering slightly above the flowers and
feeding by inserting their long feeding spout ( proboscis) down into the center of the plant.  The
butterfly then extracts the nectar which is comprised of 25-30% sugar.  This provides all the energy
the butterfly will need to exist.

As the swallowtail flits about, it must constantly be on the alert for predators.  They cannot outfly
birds and must rely on other means to survive.  Their body markings helps them to blend into their
colorful surroundings.  Caterpillars have a gland, the osmeterium, located in their neck, that gives
off a pungent and offensive odor which keeps wasps and flies away.  Flies like to lay their eggs
on the surface of the caterpillar.  As the fly eggs hatch, they burrow into the caterpillar and feed
from the caterpillar's fluids, which in turn, causes a rapid death.
 
 

The male Swallowtail butterfly (Papilio glaucas) is a strong flier with yellow and black markings
which resemble the markings, or stripes, of tigers.  Female swallowtails are most generally black in
color with occasional spottings of blue or yellow spots but there are also species in which females
closely resemble the markings and coloration of males.

This species, commonly called the eastern tiger swallowtail, has a range covering  New England
west through the southern Great Lakes area and through most of the Great Plains states and south
to Florida and Texas.

One of the two swallowtail species discussed in this study (Papilio glaucas)..the eastern tiger
swallowtail, has a wingspan of around 4-5 inches, however, the wingspan of the entire swallowtail
species may range anywhere from 3 inches to around 7 inches for those larger species found in
the more temperate regions of  the world.  The swallowtail's taste sensors, or what we might call
our taste buds, are located on the ends of their legs.

The image above is of a western tiger swallowtail (Papilio rutulus).  This species is similar to
the eastern species in coloration.  Wings are black and pale yellow with black tiger-stripes. Blue
spots are found along the trailing edge of the hind wing.  Their range is Western North America,
into eastern  British Columbia into eastern North Dakota, then south to northern Baja California
and southern New Mexico.  This species are rarely found in Nebraska, Oklahoma or Texas.  A
favorite food of the larval stage is the leaves of the California Sycamore.

Although most species of the swallowtail are in no danger of becoming extinct,  the British
swallowtail (Papilio machaon britannicus) population has been greatly diminished by the
destruction of their native wetland habitat to make room for the growing of crops.  This species
is now protected by various conservation decrees.

Below is the range of the swallowtail butterfly ( includes all species).

Check back next month for September's "Creature of the Month" The Andean Condor.

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