Answer: There is a bougainvillea caterpillar (Asciodes gordialis) that can cause leaf damage during the summer months. It's difficult to control a pest that you don't see, so I wouldn't spray the plant 'just in case' a pest shows up. But, if you discover the critters munching down, you can use the botanical Bt (Bacillus thuriengensis). This product is a stomach poison so the caterpillars need to consume some before it will work. Therefore, treat only if you find the pests.
Hope this helps solve the mystery!
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