You may apply Monterey B.t. RTU up to and on the day of harvest.
Yes, Monterey B.t. RTU should kill all caterpillar types.
Monterey B.t. RTU is not labeled for citrus fruit, including lemons.
We would recommend using Natural Guard Spinosad Landscape and Garden Insecticide instead. It is labeled for use on lemons and will kill caterpillars on the tree. One bottle will treat approximately 5300 square feet.