Q.Lemon tree
The bug on my tree is just under a centimetre and is round. Can’t see evidence of chewing but some leaf curl. New crop seems ok. When squeezed they bleed an orange red colour. Beneath the hard top minute tendrils go all the way round almost like a tiny mushroom
Certified GKH Gardening Expert
This sounds like a but called scale. This is a common infection. This link will take you to ways to make your own pest control: https://www.gardeningknowhow.com/special/organic/
This article will give you more information about scale: https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm