What do Wrens eat?

Wrens eat mostly Spiders and insects. During the summer they wont have much trouble finding food, but the winter can be difficult for them. Occasionally they will eat grated cheese, but the best thing to feed them is mealworms, preferably live ones if possible. (available on the net)

Another possibility is ants eggs, from any aquarium/pet shop. Soak them for a minute in cold water until they're a bit sticky to prevent them from blowing away.

Plant insect attracting shrubs. Coteneaster plants are a haven for insects, they overwinter in them, so are Excellent for attracting wrens.