Q.Holes in Camellia leaves
Appear to have been chewed but no sign of any insects, only lots of spider webs. There are irregular shaped holes in middle and edges of leaf (more predominantly in middle) that start as a brown patch on underside of leaf and progress to a hole right through it. Similar holes in Feijoa leaves in same garden.
The presence of spider webs may indicate the presence of spider mites. You can read more about spider mites and the prescribed course of treatment here:
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-treatment.htm
As for the brown patches on the underside of the leaves that progress into holes, my best guess is that this is some sort of fungi leaf spot fungi. In such cases, the center of the leaf spot will dry up and fall out, giving the leaf a "shot hole" appearance. Can you upload a photo of your camellia leaves? I was wondering if they looked something like this:
https://www.rhs.org.uk/advice/profile?pid=568
Irregular shaped holes in leaves could also be caused by slugs or even caterpillars but that kind of damage is usually not preceded by brown patches on the underside of leaves.
For more information on camellia plant problems, please visit the following link:
https://www.gardeningknowhow.com/ornamental/flowers/camellia/identifying-and-fixing-problems-with-camellias.htm
https://www.gardeningknowhow.com/ornamental/flowers/camellia/sooty-mold-on-camellia.htm
