This pretty caterpillar was munching on a tartarian honeysuckle plant (a non-native, invasive species). The caterpillar will turn into a striking moth which looks very similar to a large bumblebee. Its close relative, the hummingbird clearwing moth, is often mistaken for a hummingbird at first. Both are similar to each other, but this species is smaller and paler. Both will hover at flowers, as hummingbirds do, nectaring. The adult can be seen here:
http://www.pbase.com/laroseforest/image/136918919