boa constrictor, python
蟒 refers to large constricting snakes, specifically boas and pythons.
蟒 combines 虫 (insect/reptile) with 莽, which likely contributes the sound. The character specifically denotes large snakes like boas and pythons.
The insect radical 虫 on the left hints at a creeping creature, while the right side 莽 looks like a tangled mass of grass and strokes, like a huge snake coiled in the jungle.
For ボウ, imagine a boa constrictor squeezing a bow (as in bow and arrow) until it snaps: bow -> ボウ.
large snake