Hamma sp. (Hemiptera: Auchenorrhyncha: Membracidae)
Membracidae: a rhapsody of form and, probably, function.
Scrolling through images of membracid species is like watching an evolutionary parade of “one-upmanship”, each trying to reject the current species’ claim to being the most bizarre-looking animal on the planet, for which Hamma deserves serious consideration. As for function – it is nearly impossible to believe that Hamma’s spines and spikes have no effect on deterrence of potential predators. Imagine the poor bird trying to swallow Hamma. Ouch.
Membracidae is a large family numbering over 400 genera and 3200 species worldwide. They belong to the very large order Hemiptera, with about 80,000 species. All members of the suborder Auchenorrhyncha (42,000 species), to which the insect of the week belongs, feed on plants by piercing the stem with their sharp tubular mouthparts and drinking the phloem. Thankfully, few Auchenorrhyncha species are serious pests of plants on which humans depend. Membracidae prefer woody vegetation over herbaceous plants, thus their common name, “treehoppers”. Because they feed only on plants, treehoppers haven’t had to develop particularly interesting behavioural strategies to bridge host defences, as have many of the flesh-eating parasitoids which must avoid the defensive responses of their invertebrate hosts (e.g. think of the parasitoid Kapala ivorensis of week 21 fooling its ant hosts into mistaking it for self). However, there are other threats that treehoppers must contend with. When a membracid finds a good host it may remain on that plant for its entire life, and this can expose it to predation. However, treehoppers aren’t defenceless and, like many other bugs, membracids recruit aggressive ant mutualists to guard them, in return providing the ants with honeydew excreted by the bug. Also, the females of many membracid species guard their eggs by sitting on them, making it physically impossible for egg parasitoids to inject their eggs into those of the membracid. After hatching, larvae are able to communicate with their mother and siblings by shaking their bodies to announce the discovery of a good source of food or to warn of the presence of potential enemies.
A correction: As Andy Polaszek kindly reminded me, the suborder Homoptera has long since been divided into three large suborders (Auchenorrhyncha, Heteroptera and Sternorrhyncha) and one very small suborder, Coleorrhyncha. Alas, Homoptera is no more. Too bad - I liked very much the sing-song sound of “Hemiptera, Homoptera”.
For some of the above text I relied on the online thoughts of Stuart McKamey a world expert on Membracidae at the US Department of Agriculture.
Credits: Dr Robert Copeland