The simple song of the Blue-winged warbler, or Vermivora pinus, is often heard in brushy fields and thickets in the east during the summer. Even though this warbler is not very shy, it can be challenging to find it as it forages in the dense brush.
This 11.5 cm long bird has olive-green upperparts and bold yellow underparts. It also has a bold yellow crown with and black eye line. Its wings are blue-gray iwth 2 white wing bars. The blue-winged warbler's undertail coverts are yellowish to white.
The diet of the blue-winged warbler consists of mainly insects and spiders. It usually feeds on small insects, including beetles, ants, caterpillars, and grasshoppers. This bird usually forages by moving about in low shrubs and trees. It commonly probes its bill into curled leaves.
This bird can also be found at bird feeders searching for sunflower seeds.
The nest is well concealed in grass or blackberry vines, sometimes under a bush or sapling. It is placed close to or on the ground. The nest is bulky and shaped like a deep cone, and usually built by the female alone. It is constructed of dead leaves, grass, and beech or grapevine bark, and lined with plant fibers or animal hair.