Not to mention that some insects even have a bit of contrast between the lenses so it’s easier to understand they are compounded.
And additionally due to individual lenses compounded eyes arent smooth - by reflecting light at different angles you can make the “bumps” obvious.
Also if there is like a water droplet on grasshoppers eyes you can clearly see it’s surface structure. Just like you can see individual pixels on your (high dpi phone?) screen the same way.
The eyes don’t make sense to me. How did they know to use this pattern? Are there some really big grasshoppers out there?
No doubt there are insects big enough to be able to see the patterns on the eyes without magnification.
Tho I bet they didn’t study this ones eyes:
It’s called a fairy wasp (wiki/Megaphragma_mymaripenne) and it’s only the third smallest insect known.
I’m sure they had plenty of experience with bugs in their environment, both alive and dead. I’m sure you can see the eyes pretty well close up.
The aliens lent them a magnifying glass
Grasshoppers can get quite big
https://www.flickriver.com/photos/artour_a/266458852/