Warblers are normally insect eaters, and some small fruits. Will eat suet at feeders, even peanut butter spread on tree bark.
The yellow warbler consumes mainly insects, and caterpillars.
Warblers eat mainly insects, but also some fruits.
Warblers eat spiders, grasshoppers and other insects Many warblers will eat suet at feeders, and small berries and buds, as well as items named in above answer.
berries in the winter, insects like meal worms in the summer