Is this damage from caterpillars or bud rot?

Initially I thought this may be bud rot, but then I noticed a caterpillar on each bud near the damage almost every single time.
Any help would be appreciated. The brown patches fall out very easily and there is a very small, thin, fine white cobweb looking string deep inside the bud. Is it from the caterpillars or are the caterpillars just a coincidence and it is actually bud rot or something else?

Also, as it started to get closer to winter, I noticed the plant becoming purple. Some nights the temp would have got extremely cold (5 deg Celsius) and a lot of dew overnight. Is the purple colour a result of the cold temps or more to do with the strain (I have no idea what strain apart from it being Sativa) I assume the cold temp and colour is unrelated to the brown patches problem mentioned above, as the patches are only in small sections and when I remove them, they don't seem to spread. We are well into winter and I still have a few buds on the tree as I want to experiment and bring out more CBD in the buds. It' starting to get really CBD heavy now, few more days and I'll bring her in.

See brown patches below:

See one of the brown patches that easily fell off the bud when pulled below:

See the caterpillar found near every brown patch below:

See the bud starting to purple below:
 
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