Abstract
Troides aeacus formosanus, an endemic butterfly subspecies of Taiwan, is listed as a protected
species of Taiwan. Its population is mainly distributed in the Kenting area of southern Taiwan,
where Aristolochia zollingeriana serves as the butterfly’s main host plant. We surveyed the host
plants in the Kenting area, and recorded numbers of eggs laid by female T. aeacus formosanus,
larval survival rates, and habitat variables. Our goals were to determine the characteristics of sites
selected by female butterflies for oviposition, their preferred sites for ovipositing larger egg batch
sizes, and habitat variables associated with higher larval survival rates. The results showed that
70% of the 83 identified potential habitat sites were utilized by T. aeacus formosanus. Habitats
under a closed canopy were more frequently utilized by females than those under an open canopy.
Larger host plants growing in the upper level of the forest also had a higher female utilization rate.
During the field study, 101 egg batches were identified with a total of 1078 eggs. We found that
females preferred to lay larger egg batch sizes on host plants with more leaves, host plants growing
in the upper strata of the forest, and host plants by the road edge under an open canopy. Among egg
batches, the larval survival rate averaged 5.7% and peaked at 40%. We found that host plants that
were growing in the upper level of the forest and with greater leaf abundances hosted egg batches
with greater larval survival rates. As for habitat types, although females laid more eggs by the road
under an open canopy, their larvae did not have higher survival rates than larvae in other habitat types. Ultimately, vertical stratification and leaf abundance of A. zollingeriana were the most important
factors influencing female oviposition preference and larval survival rates.