Insects are an incredibly diverse class of animals. The sheer number of insect species is both very intimidating and quite comforting — at least with insects around I know I’ll never run out of animals for this blog. Today’s family of insects, the treehoppers, contains around 3,200 species. Yup, just one family of insects has over three thousand species. Insects are crazy critters.
Treehoppers belong to the family Membracidae, which also includes insects known as thorn bugs. With such a large number of species in the family, it’s no surprise that these guys are found on every continent except Antarctica.
Treehoppers and thorn bugs are distinguished by the strange shapes of their dorsal thoraxes (more technically called pronotums). These are often modified into thorn-like protrusions, but can also be more fantastical shapes. For those species that imitate thorns, the purpose of the modified pronotum is fairly obvious: you’re not likely to be eaten if you look like a thorn. For some of the more outlandish designs (such as the ornaments found on the Brazilian treehopper, pictured below), the function is still unknown.
Treehoppers feed on sap, either that of hardwood trees if they are mature hoppers, or of shrubs and grasses for younger insects. They form a number of mutualistic relationships with other species, including ants, wasps and geckos. Ants are attracted to the sap treehoppers extract from plants, and often congregate around groups of treehoppers. The treehoppers benefit from the ants’ presence by gaining added protection from predators. The same sort of relationship exists between the wasps Parachartergus apicalis and Parachartergus fraternus and treehoppers, with wasps actively protecting treehopper nymphs, and in return feeding on honeydew excreted by the nymphs. It seems treehoppers are pretty popular bugs.
Unfortunately not every creature is as kind to treehoppers; some wasps parasitize treehopper eggs and others try to eat them. To try and protect their brood, most female treehoppers lay their eggs inside the stem of plants, and some will sit on top of their eggs, waving their wings at any predators that come too close. In other species, groups of females will work together to protect their eggs.
Next time I see some thorns on a plant, I’m definitely going to check and see whether they are actually thorns, or treehoppers. Hopefully I’ll get to see some of these guys!