If they dont take bllodworms (Tubifex), then it must be the stress. Transport as well as new environment really make sals and newts feel uncomfortable for some days.
Regarding earthworms: many will not take the so-called Tennessee Wiggler (Eisenia foetida) as it produces a yellow liquid stinking like a skunk (at least close to). Some eat them without problems. Best let the worms stay in clean soil without organic consumptable material then they will "smell" better.
Best food in general are all kind of earthworms, then crickets, woodlice, blanched snail-meat (wild snails can and will contain dangerous parasites! especially Nematodes, and other parasitic worms). In summer I feed grashoppers and crickets from my yard without problems. Snails (with or without shell) only blanched (pre-boiled). Newts will as well take mussel meat which carries no harm for parasites (not for neotenous specimen as Axolotl because of the contained iodine).
Butterflies, caterpillars, and spiders often carry a wide variety of parasites and I dont feed them anymore.
best food for juveniles are Drosophila and when a little more grown Buffalo Worms plus small crickets. See jow they explode in size!
I add minerals and vitamins as used for reptiles to the food for feeders resp. powder them before feeding to my sals and newts.
Steffen