Twilit Bloat

This is the mother bug of the Twilight Parasites and also kind of a mini-boss. How to defeat her is when she isn't charging you or is electric, L-target her and jump on to her lower section, keep a hold of the L button and repeatedly press A to bite her furiously. Repeat these steps a few more times and she will eventually fall into the water laying on her back. Jump on her belly and use your energy field to attack her six tentacles, once they are all destroyed she is too.