Bothriechis schlegelii is among the most variably coloured of all snakes. The best-known form is the uniform golden oropel, but the species also occurs in leaf green, lichen grey, pink-flushed and speckled brown patterns, and the different morphs interbreed. Litters of live young can contain more than one colour.
The adaptive question is unresolved. A green snake is cryptic in foliage, but a bright yellow one on a green leaf is conspicuous, and it is not obvious how such a morph persists. Suggested explanations include matching flowers or ripening fruit that attract prey, frequency-dependent predation in which any rare pattern is harder for a predator to search for, and simple neutral variation. None has been settled.
The eyelashes themselves are modified supraocular scales, and the leading suggestion is that they protect the eye while the snake pushes through vegetation. The species is bright, small and often found in banana and coffee shipments, which is why it turns up in medical reports far outside its range.