Butterflies of the San Francisco Bay Region

By J. W. Tilden

This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1965.

• Language: English
• Publisher: University of California Press
• Release date: Dec 22, 2023
• ISBN: 9780520320697

J. W. Tilden

Enter the Author Bio(s) here.

Book preview

California Natural History Guides: 12

BUTTERFLIES

OF THE

SAN FRANCISCO BAY REGION

BY

J. W. TILDEN

ILLUSTRATIONS BY GENE M. CHRISTMAN

UNIVERSITY OF CALIFORNIA PRESS

BERKELEY, LOS ANGELES, LONDON

UNIVERSITY OF CALIFORNIA PRESS

BERKELEY AND LOS ANGELES, CALIFORNIA

UNIVERSITY OF CALIFORNIA PRESS LTD.

LONDON, ENGLAND

© 1965 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

SECOND PRINTING, 1974

ISBN: 0-520-01268-2

LIBRARY OF CONGRESS CATALOG CARD NUMBER: 64-24888

PRINTED IN THE UNITED STATES OF AMERICA

CONTENTS 1

CONTENTS 1

INTRODUCTION

WHAT ARE BUTTERFLIES?

HOW TO STUDY BUTTERFLIES

IDENTIFYING BUTTERFLIES

KEY TO SAN FRANCISCO BAY REGION BUTTERFLY FAMILIES

BAY REGION BUTTERFLIES: SPECIES ACCOUNTS GRASS NYMPHS, SATYRS, AND RINGLETS (FAMILY SATYRIDAE)

MILKWEED BUTTERFLIES (FAMILY DANAIDAE)

BRUSH-FOOTED BUTTERFLIES (FAMILY NYMPHALIDAE)

METALMARKS (FAMILY RIODINIDAE)

BLUES, COPPERS, AND HAIRSTREAKS (FAMILY LYCAENIDAE)

WHITES AND SULFURS (FAMILY PIERIDAE)

SWALLOWTAILS AND PARNASSIANS (FAMILY PAPILIONIDAE)

SKIPPERS (FAMILY HESPERIIDAE)

Tables of Blues, Coppers, and Hairstreaks

Tables of Skippers

SUGGESTED REFERENCES

CHECKLIST OF BAY REGION BUTTERFLIES*

INTRODUCTION

Of the 682 North American butterflies, 122 have been recorded from the San Francisco Bay region. Eight of the ten families of the Nearctic Region are found here. The only butterfly families not represented in our area are the Libytheidae, represented by two North American species ranging from Arizona to the Atlantic coast and up to Canada in the east, and the Megathymidae, consisting of several yucca-boring skippers confined to the area from southern California to Florida.

Our local butterflies vary in size from the tiny Pygmy Blue (Brephidium exilis), one of the world’s smallest butterflies with a wingspread of less than one-half inch, to the Two-tailed Swallowtail (Papilio multicaudata), with a wingspread of from four to six inches.

With the help of this volume you may learn where to find our Bay region butterflies and their caterpillars; how to identify them; how to study them and record your observations; and how to make a butterfly collection. Sources of additional information are provided for those who may wish to delve more deeply into the subject.

Information is provided for all 122 species recorded from the San Francisco Bay region and a handy checklist which doubles as an index to species accounts and illustrations is included. Nearly all species are illustrated; 70 in color, and the others in black and white.

Although butterflies are among the most conspicuous of insects there are many gaps in our knowledge of the details of the habits and life histories of even many of our common species. Thus such terms as early stages unknown or food plant not recorded many occur all too frequently in the accounts to follow. For this reason even the beginner may be able to make worthwhile contributions to science through keeping careful records of his observations of our San Francisco Bay region butterflies and their caterpillars.

WHAT ARE BUTTERFLIES?

Butterflies and moths are closely related. Together they make up the order Lepidoptera, which means scaly-wings. If you examine the powder which will come off if you touch a butterfly or moth wing, you will see why they were given this name. You will see overlapping rows of scales, somewhat like those of a fish in appearance. Each butterfly has its own distinctive scale shape and arrangement (see below).

You may wonder how to tell a butterfly from a moth. All butterflies normally fly in the daytime and most moths fly at night. However, there are many day-flying moths that could be mistaken for butterflies. You may think of butterflies as slender-bodied, brightly-colored insects, and moths as heavy-bodied and dull-colored.

However this does not really serve to distinguish them for you may find quite a number of slender-bodied, brightly colored moths as well as some butterflies that are heavy-bodied and dull-colored. The most convenient method of telling butterflies from moths is by looking at the feelers or antennae. Butterfly feelers are swollen at the tip into a knob or club (see above). Moth antennae may be thread-like, comb-like or feathershaped, but not clubbed.

The body of a butterfly, like that of all insects, is composed of three sections — head, thorax, and abdomen. The head bears the