the larva of locust
蝝 centers on the larval stage of a locust, specifically the young, wingless form of this insect.
蝝 combines 虫 (insect) with 彖, which likely contributes the sound. The character specifically denotes the larva of a locust.
The insect radical 虫 on the left tells you it's a bug, and the right side 彖 looks like a squiggly little larva with a head and tail. Picture a tiny locust larva wriggling around.
For エン, imagine an entomologist studying the locust larva: the 'en' in entomologist cues エン, and the scientist is examining the wriggly bug.