Wednesday, 24 August 2016

Incredible Invertebrates #03: The insect with the strangest headgear in the world?

First of all, a little update on the wasp nest in the shed - it's got bigger. The shed has now become a hive of activity (pun intended), and the nest itself is now several times its previous size. If you go around the back of the shed and put your ear against it, then you can hear the wasps buzzing in their nest! A few nights ago someone tried to break into our shed, and although they were scared off by the alarm, I imagine if they were not deterred by that, they would be in for a painful surprise! As I said to my dad, we should put a sign on our shed saying, DANGER: GUARD WASPS AT WORK. ENTER AT YOUR OWN RISK.
Anyway, now onto our incredible invertebrate . . .

Bocydium globulare is a kind of treehopper, belong to the suborder Auchenorrhyncha, which are true bugs. Groups and families belonging to this suborder include froghoppers, cicadas, and leafhoppers, as well as treehoppers. The latter contains around 3,200 species, and are found on all continents except for Antarctica. They often have an unusual or large pronotum, which can form spines, or sometimes stranger shapes.
Perhaps the weirdest of the family, however, is the Brazilian treehopper. Before I even begin to talk about this thing . . . just look at it.

This is a model of the Brazilian treehopper, but the real insect looks exactly the same. Please note: this image does not belong to me

This strange insect can be found on Tibouchina plants, and is mostly solitary. Other than that, the information on its behaviour and lifecycle seems pretty limited, but there's plenty of information about its strange headgear.
The ball-like structures are not eyes, despite appearances, but hollow chitinous spheres. But what on Earth could they be for, and why is there that long spine emerging from the back of the structure?
My first thought was something to do with mating. Perhaps sexual selection has led these creatures to evolve more and more elaborate ornamentation? Or it could play a role in males fighting for females, rather like stag beetles.
It turns out, other people have had the same idea, but dismissed it, because usually such strange ornamentation is only present in males of the species. However, in the Brazilian treehopper, both males and females bear this strange headgear.
Bearing this is mind, it seems likely that these true bugs use their crest for defensive purposes. Say, for example, that a bird spots one of these animals, and decides to have a snack. Those strange spines and spheres would make it difficult for it to get a hold on its prey, and even if it managed to get past that, can you imagine swallowing something like this? It would be very difficult, and probably painful.

You may notice from the model that the headgear is covered in strange hairs. The exact purpose of these is not known, but they may serve as an irritant, strengthening its defence mechanism. Another idea is that they could be sensory.

The Brazilian treehopper is not the only strange treehopper. Umbonia crassicornis, the thorn bug, mimics a spine to escape predator's attentions.

By Marshal Hedin from San Diego - Umbonia crassicornis (F Membracidae)Uploaded by Jacopo Werther, CC BY 2.0,
Above: a group of thorn bugs on a branch

 There are many other strange treehoppers, but that's to be discussed another time.

Until next time, keep on the wild side!

1 comment:

  1. Love this! My son was asked to make a model of an insect and after some research he chose the Brazilian Treehopper, and that's how we found this page. So interesting! Keep it up!