flea beetles

[lottie dolly]

if i were to put up a solid barrier,would this stop the little critters,thus keep them of the crops,if so how high would you recomend,i think it's aprox 2ft for carrot root fly?,please can someone confirm this for me also please,i am tying to get barriers/net cages ext sorted out in readyness for the season whilst things are a bit quieter,
many thanks