When encountered on their own, Magic Insects are an absolute joke. You will just plow right through them. Their Charge Magic ability won't seem to help them out at all, as you send them to their graves. The thing about them, is that when they are absorbed by Bogimoray, in that particular boss battle, they bring Bogimoray one step closer to performing his ultimate attack, Para-Flare. That's really the only point of their existence. Note that in that fight, if defeated or absorbed, they may use Appear to... reappear. Basically new enemies will enter the fight, but it is displayed as a skill so it will be considered as such.