The 'cheek' is the common name for the insect GENA.
The gena is located in the head area of insects. The gena forms the sclerotized area on each side of the head, below the compound eyes, which extends to the gular structure. The gena varies among species of insects.
Answer:
Humans see optical illusions when the visual system (the eyes and the brain) attempts to interpret an image that evokes a perception that deviates from reality. Your brain displays an image that makes the most “sense,” but it is not always what is actually in front of our eyes.