The suitability for larval development of the alien coconut pest Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae) on the following 15 monocots was investigated. Arecaceae: Cocos nucifera, Trachycarpus wagnerianus; Typhaceae: Sparganium erectum, Typha latifolia; Poaceae: Avena sativa, Echinochloa esculenta, Hordeum vulgare, Oryza sativa, Sorghum bicolor, Zea mays; and Cyperaceae: Carex morrowii, Cyperus alternifolius, Cyperus esculentus, Cyperus serotinus, and Rhynchospora colorata. The larval survival rate to the adult stage was significantly higher when reared on C. esculentus and C. serotinus (95%); however, it was not significantly different compared with C. nucifera (75%). Sixty, 45, 45, and 10% were observed when reared on T. wagnerianus, S. erectum, T. latifolia, and C. alternifolius, respectively. The larval developmental period reared on C. serotinus was as short as on C. esculentus and on C. nucifera up to adult emergence. The fecundity of adults was examined using C. nucifera, T. wagnerianus, T. latifolia, C. esculentus, and C. serotinus as food plants. In these five plants, the females reared on T. wagnerianus started to lay eggs earliest. However, the preoviposition periods on C. esculentus and C. serotinus were not significantly different from those on C. nucifera and T. latifolia. Numbers of eggs laid per female did not differ significantly among these five plants. Our present results suggest that T. wagnerianus, C. esculentus, and C. serotinus can be used as new food plants in addition to C. nucifera and T. latifolia for rearing B. longissima.