
Ochre Dagger Moth Caterpillar - Acronicta morula
The instars of this species vary in appearance. I think this one would be the penultimate instar, which is lime green with dark, dorsal markings, especially on A1, A4, and A8.
This caterpillar typically feeds on elm. I found it on a bridge in a deciduous forest.

The ochre dagger moth is a moth of the Noctuidae family. It is found from Saskatchewan to Nova Scotia, south to Florida, west to Texas. The wingspan is 40–50 mm. Adults are on wing from April to September in two or more generations depending on the location. The larvae feed on the leaves of ''Ulmus'' and also ''Tilia'', ''Malus'' and ''Crataegus'' species.