There are several ways to control beetles and other pests that may be damaging your plants. You can try the following remedies if they work.
Natural way - Neem is an organic insecticide that can be effective against many pests. Just mix neem oil with water and spray it on the plants as per the manufacturer's instructions.
Embrace polyculture - Try practicing growing different varieties side by side.
Cover your plants - Covering your plants with netting can help prevent pests from getting to them in the first place.
Special Note - I am writing this in the morning time, and these are the only things(mentioned above remedies) that strike in my mind.