This is a strange concept for a game, and I think I quite like it. I still don't understand why the player character thought betting body parts would be a good idea, but I digress. The whole premise of each body part having different effects and punishments is really nice. Also, it's nice to see each insect (spider is not an insect) has its own attack pattern, and that really brings up the variety in the gameplay. I also like the art a lot, which has that cartoonish cruelty charm to it. Music is also fitting, and generally, the game is quite polished. Nice job.
A minor nitpick from me is that, although there are many options and effects, which is well and good, all options are thrown there right at the beginning. From the player's standpoint, there is just too much stuff to read and understand in order to play the game. It would be way better if there were some sort of onboarding to the game that explains the mechanics (and a few introductory organs) in a digestible manner. Another nitpick is that once the fight button is pressed, there is absolutely no way the player can influence the battle. At least give us a way to fast-forward the battle, or ideally, some small stuff that can be done to make passing that time a bit more enjoyable. I once locked in a battle where both of the insects were attacking much but were constantly healing, resulting in a long and drawn-out battle that took at least 5 minutes.
Anyway, with all that said, this is still a very solid entry! Well done!