This is a green Caterpillar. It is a very pesky pests. You need to check your plants daily so that you can spot a caterpillar infestation before it gets out of control. As soon as you see one caterpillar, check the plant for more other tiny eggs.
Remove all the caterpillars you see, dropping them into a bucket of soapy water and squash them.
You can also crush all the eggs or pick of the whole leaf and destroy it if the plant has plenty to spare.
Repeat the process daily.
Still, it these methods does not work, then you can consult some pest control Benicia CA team or any other local exterminator who will use natural pesticides to control caterpillars.