You can protect young cucurbit seedlings from cucumber beetles by covering them right after planting with floating row covers, individual screens, or cones. It's also a good idea to plant cucurbits later in the season -- those planted early (by your neighbors, perhaps) will attract any beetles in the area, and your plants may be spared. Also, remove and destroy (don't compost) plants infected with bacterial wilt immediately so that they wont' attract more beetles to the area. Adult beetles found on plants can be hand-picked and squished.