What is that weird little yellow spikey bug which hops into the air?
They are the remarkably evolved Planthopper nymph (or flick bug, as I know them). Here are a couple on a leaf below.
In this case nymph means the immature form of an insect which undergoes gradual metamorphosis before reaching its adult stage. A nymph's overall form already resembles that of the adult, except for a lack of wings (in winged species). See my post on nymphs, larva and naiads for more explanation of this!
Here is one next to the adult it will become
A planthopper is any insect in the infraorder Fulgoromorpha, exceeding 12,500 described species worldwide. The name comes from the adults fantastic resemblance to leaves and other plants of their environment, and that they often “hop” to move quickly and/or avoid predation.
So why do they the nymphs look so strange, and what are those long white filaments on its bum?
Those long white strands are actually wax, made from special glands on the abdominal terga and other parts of the body. These decorations seem to serve many purposes: - To avoid predation; firstly their wax filaments break off easily, so a predator trying to grab it is left with a pile of fluff, but no meal. Also perhaps the shape mimics insecticidal fungus, so it looks like an infected corpse. - Apparently they can fan the threads out while its in the air, and to help them glide as they fall.
- As they feed on plant sap, which is essentially sticky wet sugar, and this is very prone to fungus and bacteria, so by covering themselves with wax, they can use the wax as protection.
And how do they jump like that?
These nymphs have a biological gear mechanism at the base of the hind legs, which keeps the legs in synchrony when the insects jump. These gears are not present in the adults,
This was taken on 12th May, and you can see the profusion of the nymphs and the adults too.
Unfortunately, planthoppers are often vectors for plant diseases (In epidemiology, a disease vector is any agent that carries and transmits an infectious pathogen into another living organism), which they spread when feeding.