Honeybees can learn to recognize individual human faces

Despite having a brain the size of a grass seed, honeybees trained with a sugar reward can pick out one specific human face from a lineup of photos, and even generalize the skill to differently lit versions of the face they'd learned. They likely aren't recognizing "faces" as such — they seem to treat them the way they treat unusually patterned flowers.

— Adrian G. Dyer, Christa Neumeyer & Lars Chittka, Honey bee — Journal of Experimental Biology, 2005