Adult males have pale cerulean blue upperparts and white underpants with a black necklace across the breast; they also have black streaks on the back and flanks. Females and immature birds have greyer or greenish upperparts, a pale stripe over the eye, and no streaking on the back and no necklace. All of theses birds, regardless of their age, have wing bars and a thin pointed bill.
They forage actively high in trees, sometimes catching insects in flight. These birds mainly eat insects.
The song of this bird is a buzzed zray zray zray zray zeeee. The call is a slurred chip.
In fragmented forest areas, this bird is vulnerable to nest parasitism by the Brown-headed Cowbird. This bird's numbers are declining faster than any other warbler species in the USA; its population nowadays is less than one-fifth of what it was 40 years ago