Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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 All Rights reserved. No part of this book may be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the Publisher. Published by Willow Creek Press, Inc. P.O. Box 147, Minocqua, Wisconsin 54548 All photographs © Judy Burris, Wayne Richards and Christina Richards except on the following pages p23 top left © WavyBxl/Alamy Stock Photo; p24 © Ivan Kuzmin/Alamy Stock Photo; p50 top right © Rick & Nora Bowers/Alamy Stock Photo; p52 © Robert Shantz/Alamy Stock Photo; p92 © Robert Shantz/Alamy Stock Photo; p98 © Rick & Nora Bowers/Alamy Stock Photo; p113 right © Rick & Nora Bowers/Alamy Stock Photo; p118 right © Rick & Nora Bowers/Alamy Stock Photo; p118 bottom left © Rick & Nora Bowers/ Alamy Stock Photo; p119 © All Canada Photos/Alamy Stock Photo; p124 © Bill Brooks/Alamy Stock Photo; p130 © Rick & Nora Bowers/Alamy Stock Photo; p142 © Hornbil Images/Alamy Stock Photo; p137 bottom left © Rick & Nora Bowers/Alamy Stock Photo; p137 top left © Danita Delimont/Alamy Stock Photo 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