Efts will consume springtails, young isopods, and very small worm bits. I prefer to use only the tips. You can also use d. melanogaster, but do not oversaturate the tank/vivaria. This will lead to the newts hiding to avoid over exposure. A good rule of thumb, for terrestrial caudates is that if the prey is so numerous that they are crawling on the newts(at all) the newts will curl in and not demonstrate a feeding response. If they are (green) aquatic stick to daphnia, live worm bits, and a limited amount of flightless fruit flies(D. melanogaster) on the water's surface. Garden worms are harder to collect than buying, but are the most natural food prey you can offer. They are also a staple in the diet. The fruit flies will not be consumed(ordinarily) if drown, so if you offer them, net the uneaten/dead flies out after offering. The worms will survive a day(as long as the water is not stagnant), but care should be taken to remove these as well. Most adult Eastern newts will be quite opportunistic. Brine shrimp are relished, but also will impart an abundance of salt, and should be offered at times, but not a staple. The newts will greedily consume them, but they should be offered sparingly. If you have vernal pools, you can collect fairy shrimp, and these can be offered on a more consistent basis than Brine. You do run a risk of pathogens, but I do know many keepers who will dip-net for live aquatic foods as long as you can be sure the water is stable, and uncorrupted. I hope this helps.
http://www.caudata.org/cc/species/Notophthalmus/N_viridescens.shtml (By
Xavier was a good suggestion)
JBear