kind of cicada
蟪 refers to a specific kind of cicada, the つくつくぼうし (Meimuna opalifera), known for its distinctive late-summer call.
蟪 combines 虫 (insect) with 惠, which likely provides the sound ケイ. The character was created to name a specific cicada species.
The insect radical 虫 on the left tells you it's a bug, and the right side 惠 looks like a complex, buzzing shape—perfect for a cicada that makes a loud, intricate call.
For ケイ, imagine a cicada singing a high-pitched 'K' sound that echoes like 'Kay! Kay!' through the summer trees: Kay -> ケイ.