This is a hornworm caterpillar, the adults of which are a group of moths called Sphinx Moths. Multiple species in this group occur in Maryland, and the type of plant they are eating helps with identification, as body color and pattern on caterpillars can vary with caterpillar age or genetics. Some are generalists, eating a variety of host plants, while others specialize in certain plant types. Is this individual on a Strawberry or Potentilla plant? We can't quite identify the foliage, unless it happened to fall off an overhanging tree and is wandering around on plant it's not eating (especially since most hornworm species feed on trees, shrubs, or vines).

Since several hornworm caterpillars look alike and can be hard to identify, but since this one is a bit more distinctive, our best guess is that this is a Nessus Sphinx. Their host plants are grape relatives -- wild and cultivated Grapes, Virginia Creeper, and the invasive species Porcelainberry. A gallery of the adults and a few caterpillars can be found on the linked page. Supporting this ID is this behavior note in the book Caterpillars of Eastern North America by David Wagner: "The caterpillar of the Nessus Sphinx descends from foliage to rest near the ground by day, a position for which its coloration is well suited."

Miri

Thank you for your assistance.

 

Andrew

You're welcome.

By the way I found it in the grass by my house, no trees or shrubs nearby. 

We don't know where it came from other than to say that, at some point, it was eating grape, Virginia Creeper, or Porcelainberry vines. Caterpillars can wander off of their host plant when they are done feeding and ready to pupate, so perhaps that's what it was doing. Sphinx moths pupate in the soil, rather than spinning a cocoon.

Miri