The melanic and nonmelanic ladybugs each mimic a different species of beetle which is very poisonous to birds, he says.

Some species of cat regularly produce melanic forms-the so-called black panther (actually a melanic jaguar) being the most familiar.

Melanic forms, though, are particularly prevalent in species with complicated lives—those that inhabit a range of habitats, are active both day and night, and move between the ground and the trees.