From Japanese-English FreeDict Dictionary ver. 0.1:
[ichi1] [news2] [nf26] 蛍 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, (word containing out-dated kanji) 螢 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, [ichi1] [news2] [nf26] ほたる /ho̞tˈäɽɯᵝ/, () ホタル /ho̞tˈäɽɯᵝ/
(noun (common) (futsuumeishi))
Note: word usually written using kana alonefirefly (Luciola cruciata), lightning bug, glowworm