What is eating my Red Russian kale?

c_watkins

Hello, I'm growing the kale for the first time and have seen little orangey insects on the underside of the leaves. The leaves are quite holey. 

Does anyone know what the insects are, and if they're likely to cause a problem further down the line?
Could birds or anything else like slugs be chowing down and making holes? 
Should I net the plants?

Questions, questions, thank you for any answers! 

bertrand-mabel

First culprits have to be slugs and snails.

But then pigeons love attacking the foliage of these types of plants.

Can you put in some sticks to deter possible pigeon damage and then you can determine whether it is the others doing the damage?