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 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI EP67188 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 (217 7 ■£. ' $* / This thesis, written by Mr. Bernard Eldon Brown under the guidance of h..%3... Faculty Committee, and approved by all its members, has been presented to and accepted by the Council on Graduate Study and Research in partial fulfill­ ment of the requirements for the degree of Master of Arts Date.\ Faculty Committee Chairman 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-