For bigger quantities of insects, try insecticidal soap sprays that you can find at most garden centers.
Picking off large insects and caterpillars by hand and dropping them into a bucket of soapy water is a safe, effective way to deal with limited infestations. For bigger quantities of insects, try insecticidal soap sprays that you can find at most garden centers. Whichever pest-control chemicals you use, carefully follow the manufacturers' directions.