The Gray tree frog's Latin name is a Hyla versicolor, which means that it can change its color in chameleon like fashion from gray to green, depending on the substrate, and with mottling from black to nearly white.
Holarctic Tree frogs also belongs to the genus Hyla. The genus, established in 1768, was named after Hylas in Greek mythology, who was the companion of Hercules. Some strong little creature, this tree frog!
And in case you wanted to know this, if you should plan a trip to Costa Rica, you might want to look for the Gladiator tree frog, all of 1/2 inch body length and with enormous eyes (comparatively) sticking our from its head.