This game is amazing!
Let's get rid of obvious — the polish is excellent. SFX and Music balanced pretty good, graphics look appropriate, you have good feedback on changing a level, on eating bugs, on death and it looks very pleasing to the eye. Nothing looks out of place. Good job! Nothing comes to mind trying to pin-point a place or sprite that needs visual polish.
About bugs — I found a lot of bugs, but snakes chased them (actually they chased me, but I'm sneaky) and ate them. Non actual game bugs were found.
Talking about game design — the difficulty curve is very good to my taste. Big variety of different bugs with distinct looks and behavior. All of their actions were obvious and coherent. It feels like I'm playing a well developed game fighting the actual game mechanics and not their implementation. The feature for starting from the higher difficulty is an amazing touch to overall experience.
Great game, great job!