蟀谷

From 米(こめ) (kome, “rice”) + 噛(か)み (kami, “biting, chewing”, 連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 噛(か)む (kamu, “to bite, to chew”)), from the way one's temple moves while eating.

蟀谷 appears to be a variant of 率谷(そっこく) (sokkoku, “leading valley”), the acupuncture point at the temple. First appeared in 外臺秘要, volume 39, line 255, "蟀谷在耳上入髮際一寸五分，嚼而取之。灸三壯，主醉。酒風發，兩角眩痛。一云兩目眩不能飲，煩滿嘔出。"[1]

It's not clear why the kanji 蟀 was chosen, but it was borrowed as it is into Japanese.

蟀谷(こめかみ) • (komekami) 

1. Alternative spelling of 顳顬 (“temple (region of skull)”)