Lizard beetles (Erotylidae, Languriinae, Languriini) are known as stem borers of plants and contain agricultural pests and endangered species, but their species–host plant associations have been poorly documented. Here we investigated the larval host plants of two species of the genus Tetraphala Strum, T. collaris (Crotch) and Tetraphala sp. occurring in Taiwan. Females of T. collaris excavated living leafstalks and stems of the herbaceous dicot, Sambucus chinensis (Adoxaceae) using their mandibles for oviposition. We observed the eggs and early-instar larvae inside and nearby oviposition holes and late-instar larvae inside stems, suggesting that T. collaris uses living leafstalks and stems of S. chinensis as oviposition substrate and the larvae tunnel into stems with feeding on the tissues. Similarly, females of Tetraphala sp. excavated living leafstalks of the fern, Pteris wallichiana (Pteridaceae) using their mandibles for oviposition. We observed the eggs and early-instar larvae inside and nearby oviposition holes. When reared in laboratory, a larva reached adulthood inside the leafstalk. These results indicated that Tetraphala sp. uses living leafstalks of Pt. wallichiana as oviposition substrate and the larvae complete their development within. This study revealed that the genus Tetraphala contains both fern- and dicot-users during larval period. Further study is needed to clarify the evolutionary process of host plant use of languriines. Additionally, the host plant list of Languriini is provided.
