Southern AG Malathion - Oil Citrus & Ornamental Insect Spray is specifically labeled NOT to be used on Hibiscus. According to the manufacturer, this product will damage Hibiscus due to the oil coating the leaves and causing them to burn.
Yes, Southern AG Malathion is labeled for use on camellias for scale and spider mites. It is avalable in an 8 oz and 16 oz bottles.
You will use 2 - 2 1/5 tbsp of Southern AG Malathion - Oil Citrus & Ornamental Insect Spray per gallon of water. Please refer to the product label for complete instructions on your target issue.