For years I’ve wanted to see one of the strange Membracid treehoppers, which biologists often write about but rarely find. At last I found some of them, feeding on one of our rarest tree species, Zapoteca aculeata. These bugs are only about 6-7mm long but are very complex for their size. They are related to cicadas, true bugs (like the assassin bug), and leafhoppers. The weird ones are in the family Membracidae. The species I found is in the genus Cyphonia, maybe C. trifida, though the pictures of C. trifida on the internet all show a single large yellow patch on the side of the head (see here, here, here, and here for examples) where mine have two small yellow patches.
These guys suck sap from trees, and are often social, occurring in loose or dense colonies. Mine are living on a single tree of Zapoteca aculeata. This species of tree was thought to be extinct, but was recently rediscovered here in Banos by my friend Nigel Pitman. It grows in several of our Banos-area reserves (our new Rio Machay Reserve, Cerro Candelaria Reserve,Naturetrek Reserve, Rio Zunac Reserve, and perhaps others) and we use it as one of our reforestation species when reforesting old pastures. I have a few in my yard and that is where I found these bugs. I’ve never seen them on any other tree. However such small bugs could easily escape my attention, so that doesn’t mean much.
Why do these bugs have what looks like a home-made TV antenna coming out of their backs?? Some species have even crazier horns than these, with hanging spheres and extra horns going in all directions. In one group of species, the back horns are clearly imitating big ants, which would frighten many predators. The videos below show some of those species:
In other species, the horns may imitate a common insect-eating fungus. Predators wouldn’t want to eat dead prey, so this might make sense. Some other species have elaborate horns whose functions are complete mysteries.
It has recently been discovered that these bugs “sing” to each other by transmitting vibrations through the tree stem and leaves. The vibrations don’t go into the air, just through the tree stem, so we can’t hear the sounds unless a device (like an old phonograph needle) converts the vibrations into aerial sounds. Both males and females make these songs, and a given species may have several different “songs”. Some are mating songs, some are aggressive songs, and some are warning calls. Males may even try to “jam” the songs of other males by singing a counter-song.
Listen to this NPR radio story with recordings of some songs (click on “Listen” in the NPR story page).
Here is a video made in Ecuador about these insects and their calls — I recommend you start at the 2:00 mark, the beginning dialogue is insufferable (I wish the narrator had been David Attenborough…):
And here is a whole library of calls of many different treehopper species; download any of them and listen with Windows Media Player or equivalent.
Might these vibrations be part of the reason for the weird horns on these bugs’ backs? Maybe they are resonators tuned to sense specific vibrations. The whole casque and horn assembly forms a big helmet, and itis hollow, an empty dry shell like an eggshell, with a huge airspace inside, suggesting that it might play some acoustic role. But I don’t think anyone really knows. Here is a diagram of the helmet (technically called the “pronotum”) from a recent scientific paper. The only connection of the helmet to the body is through the front legs and the neck.
Some of my pictures of these bugs are composites of many hundreds of images, each taken at a slightly different distance from the subject. These images have tiny depths of field, but the sharp parts of each image can be combined using software (Zerene Stacker). The insects are dead specimens in those pictures. I’ll add a post about this method one of these days if I can find the time.
Click here for more amazing treehopper images from Ecuador, taken by my friend Andreas Kay. Also see these amazing treehopper images from Piotr Naskrecki. And more here.