I know this is supposed to be a blog about caterpillar eyespots, but I couldn't resist posting these photos. This lantern fly flew over to where I was sitting one night and when we picked it up to take a closer look it displayed its eyespots quite aggressively.
The strange look of this species has sparked many stories and folklore; it is sometimes called "machaca" here. Their common name comes from the false belief that the structure on their head lights up like a lantern. This was apparently believed by the authority at the time, Maria Sibylla Merian, and picked up by Carl Linnaeus. This is where the specific name (i.e., the species name) laternaria came from. Other species in this genus include phosphorea and candelaria also as a result of this belief.
I have heard that this peanut-shaped protuberance is sometimes drummed against a tree, possibly as a form of communication. This would make sense because that part of the head is hollow and could be a kind of resonance chamber to deepen the drum beats, helping sound travel further into the forest. It has also been suggested that the head could be a way to intimidate attackers (it is also called an "alligator bug") by making the insect look bigger and bitey. There is a legend here that if you get "bitten" by a lantern fly you need to make love in the next 24h or you will die! After we let it go it started flying around again and when it landed on the crotch of my pants one of the other researchers here joked that I should "Watch where it bites now!" - we all had a good laugh. Actually, they are a type of planthopper and can't really bite you because they have long piercing-sucking mouthparts made for feeding on plant juices.