What bug causes this?

That looks like it happened when the fingers were still small and tucked up tight layered on each other.
The 2 most common offenders here in Southern California are Grasshoppers and Caterpillars.
Grasshoppers are to big and anything strong enough to kill them you don't want on your plant so knock them off and step on them when found. Their damage is usually limited to fan leafs and don't really hurt the plant.

Caterpillars are a whole different critter and you should be spraying for them anyway.
BT once a week every week in flower to keep them under control.


Bacillus Thuringiensis

BNW

 

I concur

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Do you spray neem as well as bt and greencure during flower? I am curious on a spraying schedule, as i feel spraying 3x a week is rough.

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Bt is ok to spray during flower

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Here in So Cal I only need to spray for Powdery Mildew and Caterpillars.
BT on Mondays. Green Cure on Thursdays.
No Neem in flower as it can leave a funky taste.
The local native population of Praying Mantis and Ladybugs keep everything else under control.

BT is soon destroyed by sunlight exposure so it needs reapplied on a weekly basis. Cure can be applied only when visible signs are seen but I prefer to treat weekly as PM is rampant here and on everything once you start looking for it.

BNW

 

Now that's a solid response, i thank you. Hardly any ladybugs here... Released 3k of them too so hoping to find some babies soon! Wouldnt want the couple aphids i found in the last few weeks to get out of control.

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What would we do without u bnw???

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