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Butterflies
of n ort h a m e r ic a
The Life History of
North American
Butterflies
Judy Burris & Wayne Richards
© 2016 Judy Burris & Wayne Richards
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Butterflies
of north america
The Life History of North American Butterflies
By Judy Burris & Wayne Richards
Design: Donnie Rubo
Printed in China
WILLOW CREEK PRESS
®
Table of Contents
Introduction to Butterflies...............................................7
Swallowtails.......................................................................................27
Whites and Sulphurs...................................................................41
Gossamer Wings...............................................................................55
Skippers....................................................................................................73
Brushfoots.........................................................................................89
Introduction to Butterflies
Butterflies are amazing insects that undergo a complete metamorphosis. These creatures have fascinated
people all over the world for centuries. Butterflies have
a complicated four-stage life cycle (egg – larva – pupa –
adult). Each stage looks completely different and serves
a specific purpose in the life of the butterfly. Winged
adults lay their eggs on specific plants on which their
larvae (caterpillars) will feed. The caterpillar grows
quickly, sheds its skin several times, and when fully
developed it becomes a pupa (chrysalis). When metamorphosis is complete, the chrysalis skin splits and the
butterfly climbs out. After its wings have expanded and
dried, it flies off to find a mate to start the process all
over again. Some butterflies have several generations in
a year, while others have only a single generation.
Zebra Swallowtail egg
Zebra Swallowtail caterpillar
Zebra Swallowtail hanging
caterpillar (pre-pupa)
Zebra Swallowtail chrysalis
Zebra Swallowtail
Butterflies in their adult stage can live from a week
to nearly a year depending on the species. Many species have long larval life stages while others can remain
dormant in their pupa or egg stages, so they can survive
months of winter weather.
Courtship is usually aerial and often involves pheromones. Once they choose a mate, the butterflies land on
the ground or on a perch to mate tail-to-tail. The male
passes a spermatophore containing sperm and nutrients
Pipevines mating
8 | Butterflies of North America
to the female during this process. If disturbed the pair can
fly off and remain connected.
Butterflies feed primarily on nectar from flowers.
Some also derive nourishment from pollen, tree sap,
rotting fruit, dung, fungi, decaying animals, and dissolved
minerals in wet sand or dirt. Butterflies are important as
pollinators for some species of plants. In general, they do
not carry as much pollen as bees, but they are capable of
moving pollen over greater distances.
Stage One—Egg
Butterfly eggs are protected by a hard outer layer of
shell, called the chorion. This is lined with a thin coating
of wax which prevents the egg from drying out before
the larva has had time to develop enough to hatch. Each
egg contains tiny openings at one end, called micropyles
that allow sperm to enter and fertilize the egg. Butterfly
eggs vary in size and shape between species. Some are
smooth and round while others are finely detailed with
ribs, ridges, bumps, dimples or geometric impressions.
Some butterfly species lay eggs singly, others in batches.
Females can produce a total of between one hundred
and many hundreds of eggs. Butterfly eggs are fixed to
a leaf or stem of the host plant with a special adhesive
which hardens rapidly. This glue is easily seen surrounding the base of the egg. This substance darkens when
exposed to air, becoming a waterproof, rubbery material
which soon sets solid to hold the egg firmly in place.
The coolest thing about a butterfly egg is that if you look
close enough, after a few days you can actually see the
tiny caterpillar growing inside.
Clouded Sulphur egg
Monarch egg
Mourning Cloak eggs
Question Mark eggs
Red-spotted Purple egg
Silver-spotted Skipper egg
Introduction to Butterflies | 11
Stage Two—Caterpillar
Butterfly larvae are called caterpillars and their sole
purpose is to eat and grow. They have a hard head with
strong mandibles used for cutting leaves and stems. They
have ten abdominal segments equipped with short fleshy
prolegs, each having tiny hooks called crochets that help
the caterpillar to grip a surface. The three pairs of true
legs on the thorax have five segments each and are used
to hold on to their food and guide it into their mouths.
Caterpillars mature through a series of growth stages
called instars. Near the end of each stage, special hormones cause the cuticle (the tough outer layer of skin)
to be released from the softer epidermis layer beneath.
Then the epidermis begins to form a new cuticle. At the
end of each instar the larva molts, shedding its outer
skin. Caterpillars have several simple eyes called stemmata that only detect light and possibly some movement. These eyes look like tiny raised dots. They also
have a tubular spinneret which is able to produce silk
like a spider. They can also have hairs, wart-like protuberances, horn-like projections and spines on their head
and body.
Pipevine caterpillar
12 | Butterflies of North America
Tawny Emperor caterpillar face showing horns and other projections
Silver-spotted Skipper caterpillar face showing simple eyes
Zebra Swallowtail showing simple eyes and gripping feet
Introduction to Butterflies | 13
Caterpillars must resort to using various tactics to
avoid being eaten by predators. Many caterpillars are
well-camouflaged to blend in with leaves and tree bark.
Others have sharp spines all over their body. Swallowtail
caterpillars have a gland hidden under the skin behind
their head called an osmeterium that can be pushed out
like a snake tongue to scare predators. Plus, it produces
a foul-smelling liquid that repels attackers. Monarchs
absorb the toxins from milkweed plants into their bodies
making them poisonous to birds. The caterpillar’s bright
coloration is a warning that it contains toxic chemicals.
Some caterpillars rear up and wave their front ends,
marked with big eyespots, as if they were little snakes.
Caterpillars may also resort to hiding in folded leaves,
roll into a ball and drop to the ground if they feel threatened, or come out to eat only at night and stay at the
base of their host plant during the day.
Silver-spotted Skipper
showing eyespots
Zebra Swallowtail
showing osmeterium
Pipevine Swallowtail
showing osmeterium
Monarch with warning coloration
Spicebush Swallowtail with eyespots
Introduction to Butterflies | 15
Stage Three—Chrysalis
When the larva is fully grown it stops feeding and
begins wandering to search for a safe pupation site,
often the underside of a leaf or other concealed location.
There it spins a button of silk which it uses to fasten its
body to the surface, and then it molts for a final time.
The naked pupa, also known as a chrysalis, usually hangs
head-down from the cremaster, a spiny patch of hooks
Monarch chrysalis
16 | Butterflies of North America
on its rear end that grab onto that button of silk. But
in some species an additional silk girdle is also spun to
keep the pupa in a head-up position. Most of the tissues
and cells of the caterpillar are broken down inside the
chrysalis, and then these materials reorganize into the
structures of the butterfly. Many of the body parts are
visible on the exterior of the chrysalis, including the
wings, antennae and tongue.
Monarch chrysalis with wing pattern
showing before butterfly emerges
Clouded Sulphur chrysalis with
butterfly ready to emerge
Red Admiral chrysalis
Pipevine Swallowtail showing
orange and violet coloration
Silver-spotted Skipper chrysalis
Red-spotted Purple hanging caterpillar
Stage Four—Butterfly
adult (imago)
The adult butterfly is the reproductive and mobile
stage for the species. The adults undergo courtship,
mating, and egg-laying. The adult butterfly is also the
stage that migrates or colonizes new habitats. Butterflies have several defense mechanisms to evade their
predators and other threats. Some, like the Monarch
and the Painted Lady, migrate over long distances to
avoid winter weather. Butterfly adults are character-
ized by their scale-covered wings. These scales give
butterfly wings their color. Melanin pigments produce
blacks and browns, uric acid derivatives and flavones
create yellows, and many of the blues, greens, reds and
iridescent colors are caused by the micro-structures of
the scales and hairs. After it emerges from its chrysalis,
a butterfly cannot fly until the wings are ready. A newly
emerged butterfly needs to spend some time pumping
hemolymph (insect blood) into its floppy, damp wing
veins and letting them dry stiff so the creature can fly.
Monarch, time lapsed wings drying
Introduction to Butterflies | 19
As in all insects, the butterfly body is divided into
three sections: the head, thorax, and abdomen. The head
contains the eyes, proboscis (tongue) and antennae. The
head is small and dominated by the two large compound
eyes. These eyes have many lenses and are capable of
distinguishing flower shapes, nearby motion and shadows,
but not for clearly viewing distant objects. Their color
perception is good, especially in the blue/violet range.
Scientists have discovered that butterflies navigate using a
time-compensated sun compass. Butterflies can see polarized light and therefore they can orient themselves even in
cloudy conditions. The polarized light near the ultraviolet
spectrum appears to be particularly important for accurate travel, especially migration, and in choosing mates.
20 | Butterflies of North America