Common Issid Bug - Issus coleoptratus
The common issid bug, or Issus coleoptratus, is a common but fascinating planthopper. Unlike most of its family members, it is unable to fly. It is also quite unique because, as nymphs, they have mechanical-like gears on their hind legs.
@dippalodoculus, hiya ! It took like a week, but I finally got the time to finish this info-post. I hope you like it :DD
[UPDATE] One of my mutuals, @bryoinformatics, made me aware of the fact that Picture Insect is an unreliable source and, in fact, uses AI. I used this source under 'Description and Life Cycle' from "The egg...-...and dispersal".
I will not alter this piece to much, however, because I did cross-reference it with some general knowledge on the species. What I will do though, is generalise it a bit more, so there will (hopefully) not be any incorrect details. I will also not remove it from my list of sources, because I did lend some of the structure for my text, and think I should still credit it. I also added the sources, I used to cross-reference (see the second and third source).
I apologise for spreading any misinformation, and hope that this will be more correct. If I made any more mistakes, please let me know. My intention is to educate, not to spread untruths.
On the Left: Adult Issus coleoptratus. On the Right: Issus coleoptratus Nymph.
Description and Life Cycle
The egg of the common issid bug is often laid in clusters. It's small and oval. The egg stage can last anywhere from days to weeks, depending on environmental conditions.
Upon hatching, the nymphs still lack fully developed wings. As nymphs grow, they molt several times, each instar showing incremental growth in size and wing development.
Emerging as an adult, the common issid bug exhibits fully formed wings and functional reproductive organs. The adult is typically displays a larger colour variation, is larger in size, and has a hardened exoskeleton. Additionally, it has a focus on reproduction and dispersal.
These adults can reach a length of 5.5–7.0 millimetres. Their colouration can vary from light brown and olive to nearly black. The head, including the eyes, is narrower than the pronotum. The forehead is usually dark brown to black in the upper third, with lighter spots. In the lower area, it is greenish, yellowish, or brownish in colour. The leathery wings typically exhibit a large number of dark brown cross-veins, accompanied by a dark brown discal spot. There is also some evidence of banding. Additionally, the common issid bug displays sexual dimorphism. The forewing veins of males and females differ. They are effaced distally in the female, while in males, they are prominent throughout.
These insects are unable to fly, unlike most members of their family.
Gear Structures on Hind Legs
Like all planthoppers, the nymphs of this insect have a small, gear-like structure on the base of each hind leg. These gear-like structures have teeth that intermesh with one another. This keeps the legs synchronized when the insect jumps, and prevents it from spiraling. The insects shed this gear before moulting into adults.
However, what is unique is that, unlike gear-like structures previously found on other animals, these were purely ornamental. This seems to be the first natural design that mechanically functions like our (man-made) geared systems.
Toothed Gears (Magnified Above with an Electron Microscope).
Distribution, Habitat and Diet
This common species can be found from May to mid-October in the western Palearctic realm, in the Near East, and in North Africa.
These insects live on shrubbery and foliage of various woody plants. They can also be found on common deciduous trees and in mixed forests, such as forest edges and parks.
They feed on the phloem, a type of vascular tissue, of different trees. Such as lime trees, oaks, maples, birches, elms, and hazels.