Thread by @sciencegirl

This is a dead leaf

Can you see that vibrant green defiant patch? That part is kept alive by the larvae of leaf mining insects, and even though its long fallen off the tree it’s still photosynthesising.

How and why?

📸images Mike Shurmer
Source cutt.ly/kQ8RqrX 1/

Leaf-mining insect lay eggs on leaves

After hatching, the larvae tunnel through into the leaf protected from predation and the plants own defences and eat leaf tissue creating little visible tunnel patterns 2/

these insects pass from generation to generation a certain bacteria that manipulates the leafs own signalling chemicals – hormones called cytokinins. These usually do many tasks preventing a leaf dying 3/

And since their whole life depends on eating leaf tissue... some plants “pretend to be ill” to avoid leaf mining insects depositing their eggs

One such plant is Caladium steudneriifolium whose leaves already “ appear”infested with larvae 4/

📸 image cutt.ly/fQ8T13y

Just to summarise leaf mining insects can be moths sawflies etc. Their larvae need the protection and sustenance of the leaf, and by keeping bits of dead leaves alive in autumn, they increase their window of reproduction into seasons where food is scarce 5/

The images In tweet one are by Mike Shurmer @mike_shurmer

The full video link for tweet 2 is here and is really worth watching cutt.ly/jQ8bXCF