(dung) beetle
蛣 centers on a dung beetle, a specific insect associated with waste. The meaning is narrow and concrete, without broader abstract extensions.
蛣 combines 虫 (insect) with 吉, which likely provides the sound. The character specifically denotes a dung beetle.
The insect radical 虫 next to 吉 (which can suggest something lucky) is ironic: a dung beetle is an insect that finds its fortune in waste.
For キツ, imagine a dung beetle rolling a ball of dung while making a sharp 'kits' sound as it works: kits -> キツ.
—