DO NEWTS EAT TADPOLES?

They do, alas. But wildlife includes a balance of prey and predators, so wiping out the predators produces an artificial not a wild community. If you have frog or toad spawn in your pond, frogs and toads are managing to survive your newts. Frogs and toads go back to their native pond to lay spawn so the newts aren't wiping them out completely. If they were, there would be no spawn. It is best not to interfere with the natural balance. Make nooks and crannies where tadpoles can hide by planting a variety of native pond plants like starwort and hornwort (Ceratophyllum demersum). Avoid damaging foreign imports like New Zealand pygmy weed (Crassula helmsii) or parrot's feather (Myriophyllum aquaticum) which are sometimes sold in aquatic shops.