Yike!
On a microscope: Objects are smaller and less alarming than they appear.
The author (alas, unknown) has to have had the same experience as I had. For some reason which is now unclear to me, we had decapitated a wasp in high school biology class, and we were now taking turns examining the head under a binocuar stereo microsocope at about 50x magnification. Apparently bugs can still twitch their antennae after they’re dead.
I’ll leave the rest of the scene to your imagination, except perhaps that was the point of having decapitated that poor bug: to scare the bejeezus out of some kid.