Mine is definitely the cucumber beetle, it’s brought my cucumber and zucchini crops to early endings. Next would be wireworms, we turned a hayfield into a market garden and hayfields tend to have large populations of them. They are the larvae of click beetles and mature in the soil for 3 years. I’ve had success with nematodes, as well as using potato and carrot pieces to lure them. And third would be onion maggot, the larvae of a small fly. This one I’m still trying to figure out as it became a big issue last season. I may try mint and oregano teas, using diatomaceous earth around base but depending on rain I could go through a lot of both. A biological like BTK might be another option.