Malacosoma americanum

The eastern tent caterpillar (Malacosoma americanum) is a species of moth in the family Lasiocampidae, the tent caterpillars or lappet moths. It is univoltine, producing one generation per year. It is a tent caterpillar, a social species that forms communal nests in the branches of trees. It is sometimes confused with the spongy moth (whose larvae look similar) and the fall webworm (which also builds tents), and may be erroneously referred to as a bagworm, which is the common name applied to unrelated caterpillars in the family Psychidae. The moths oviposit almost exclusively on trees in the plant family Rosaceae, particularly cherry (Prunus) and apple (Malus). The caterpillars are hairy with areas of blue, white, black and orange. The blue and white colors are structural colors created by the selective filtering of light by microtubules that arise on the ball cuticle.

from Wikipedia