Some contributions to the life cycle of Papilio zelicaon Lucas with special reference to the hardening of the wings

30 Pages·01.006 MB·English

by  Brown, Bernard Eldon

SOME CONTRIBUTIONS TO THE LIFE CYCLE OF PAPILIO
ZELICAON LUCAS WITH SPECIAL REFERENCE
TO THE HARDENING OF THE WINGS
A Thesis
Presented to the
Faculty of the Department of Zoology
University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
Master of Arts
hy
Bernard E. Brown
August 1950
UMI Number: EP67188
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This thesis, written by
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and approved by all its members, has been
presented to and accepted by the Council on
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Date.\
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TABLE OF CONTENTS
PAGE
INTRODUCTION 1
FEEDING 2
COLOR OF CHRYSALIS 5
WING HARDENING
History 9
Experimental
Material 11
Method 13
Experiments on the drying of the wings 14
Experiment on oxidative reaction 15
Experiment on severed wing 15
Experiment on killing the butterfly 16
Experiment with the anesthesia 16
Discussion 17
Conclusion 18
SUMMARY 19
TABLES 21
LITERATURE CITED 25
INTRODUCTION
This is a study to expand the knowledge concerning
Papilio zelicaon Dueas, and with special reference to the
hardening of the wings upon emergence from the chrysalis.
The study is divided into three parts. The first part
concerning the feeding habits of Papilio zelicaon. and the
second part relating to the color of the chrysalis are sec­
tions which deal specifically with this one species. This
information is of interest and use to further work on this
species, but probably has no general validity in the order
Lepidoptera as a whole.
The third section deals with the hardening of the
wings upon emergence. The findings presented here probably
are true for all Lepidopterans in general.
2
FEEDING
Papilio zelicaon Lucas is called the fennel swallow­
tail because the caterpillar is found typically on fennel.
This is an example of food adaptation since fennel is a
recent introduction from Europe. Parish (1920) in his paper
on "immigrant Plants in Southern California" could not say
just when fennel was introduced, but it was still "rare" in
San Bernardino County in 1890, and only "casual" in Los
Angeles County in 1898. It seems quite likely that the plant
was introduced as a garden escapee in the period between
1880 to 1900.
Comstock (1921) in his work on butterflies of California
states that the Anise Swallowtail (P. zelicaon) is common
throughout the state and that its favorite food is wild anise
(Carum kelloggi Gray). This plant is not found south of Santa
Clara County. The possibility arises that before the intro­
duction of fennel the butterfly was not in this area. There
is no easy way to check on this*
In this study the caterpillar in the field was found
only on fennel (Foenlculum vulgare Hill). However it was
found that they will eat carrot, celery, poison hemlock and
two other umbells: Qenanthe and Leptotaena, and Citrus
(orange)•
•»
Essig (1926:; 634) notes that they will eat wild
carrot, wild parsley, water hemlock and dog fennel. He also
3
states they are found on Citrus (especially orange, but are
not pests). In raising the caterpillars some difficulty was
found in trying to get them to live on orange. They usually
die, however one went into the chrysalis after an orange diet,
and a small second stage larva ate all the rind off of an
orange still green. Apparently some individuals can and will
live on Citrus.
Tests trying to get the caterpillars to feed on poplar
and lilac were failures. Other species in the genus Papilio
will feed on the plants at least in emergencies. Caterpillars
in this study starved on these plants with no sign of ever
having eaten any of the plants.
This information supports a contention that this
species will (in captivity at least) eat almost any plant in
the Umbelliferae family, and some individuals will eat from
at least one species in the Citrus genus, (Table I). Most
of the caterpillars (but not all) which were fed upon Citrus
and poison hemlock died. One might infer from this that these
two plants are not always suitable as a food plant for these
caterpillars.
In the wild state the Umbelliferae plants chosen by
the female probably depend upon other factors in addition
to the suitability of the plant as food. Such factors as
location and ecological niche undoubtedly influence the
female which lays her eggs on a plant which for her is not a
4
food plant* The factors inducing the female to oviposit on
special plants would be interesting in themselves.
In the early spring and late fall most of the cater­
pillars are found on young plants or fresh growth* During
the season when the plants were dryer and more mature most
of the caterpillars were found on the stem of the flower
clusters. Although even then if young growth was available
caterpillars were found upon it*
A marked decrease in the caterpillars found in the
field was observed during July. This could be correlated with
other factors, but it is most probably due to a small gnat­
sized wasp. This wasp lays its eggs upon very young cater­
pillars. During the second larval stage the wasp larva
emerges from the caterpillar, killing it. The wasp would form
a cocoon and in about two weeks emerge as an adult*
5
COLOR OP CHRYSALIS
Whatever the food, and In this study the caterpillars
were found only on fennel, the egg is laid on the food plant
of the caterpillar, which Is not a food plant for the adult#
In the case of fennel, plants chosen are usually younger ones,
isolated, hut near a large patch of fennel* Plowed fields
that have broken stands of fennel, roadsides and railroad ways
present good prospective locations for the caterpillars* A
dense stand of fennel is usually completely barren of larvae.
The reason behind this would be Interesting to know, since
if scent is involved one would expect to find a dense stand
as attractive as an isolated plant, especially since in most
dense stands the individual plants are usually quite acces­
sible to the butterfly.
The egg, laid on these plants, hatches in four days.
The caterpillar emerges, eats the egg case, then starts
feeding on the plant. There follow four caterpillar stages.
The first stage is a small (0.5 cm.) black caterpillar with
a white girdle. This is followed by a larger stage (3/4 cm.)
also black and white. The third stage still has the white
girdle but adds reddish dots and white spots over the feet.
The final caterpillar stage is a large (4 cm.) handsome
green animal with black and red or yellow bands on it. This
large caterpillar fattens up and then in nature leaves the
food plant to seek a spot to become the pupa. For the chrys-
alls a web mat is made on some plant or surface to hook the
cremaster into when it is developed. A life-line is then
formed around the thorax and the caterpillar settles down and
becomes the chrysalis, this forming under the skin. The old
skin is then shed, and the chrysalis hardens. The pupal
changes then take place.
- It is interesting to note that there are two different
colored chrysalids: green and brown. These two shades may
vary somewhat but are quite distinct and rather good camou­
flage, If brown, the chrysalis resembles the dead petioles
of fennel, and if green, fit in well with the green foliage.
It first appeared that there is a tendency to match
the background, that is, brown chrysalis on brown, green on
green. Of the chrysalids used in this study most were of
necessity on green fennel (although in each case brown paper
backgrounds were also available). A record kept of the number
of chrysalids on various backgrounds showed no consistent
correlation, namely of 79 chrysalids on a green background
54 were green and 25 were brown. On a brown background 5
were green and 4 were brown. The tendency to match is. appar­
ently a matter of chance, although matching the background
could possibly have survival value, (Table II).
In the chrysalid coloration however, there was noticed
a tendency for the percentage of green ones to become more
prevalent as summer came on, (Table II). This might be be-