Hi Joe,

The bugs are larvae of spotted lantern fly.  This is a relatively new invasive insect in Maryland and Virginia which is mainly important because it damages fruit crops and trees.  It has recently spread to Washington, DC.  You are asked to report sitings of the insect to the Maryland Department of Agriculture at this web site:  https://survey123.arcgis.com/share/26f9dbec58674313b1bec03ddb8b5f0e.  The insect damages plants by piercing and sucking but causes minimal damage to residential plants.  The only control recommended is physical killing (ie squashing them) or attracting beneficial insects (like assassin bugs), but not chemical spraying.  Insecticides are non-specific and will also kill beneficials which are the main line of control of lantern flies.  We also ask that you quarantine any transport of plant materials from affected counties to unaffected areas.  The University of Maryland Extension has published an excellent review of spotted lanternflies which you may find interesting.  It is at the following web site:   

https://extension.umd.edu/resource/spotted-lanternfly-management-residents

Thank you for your question and astute observation.  If you have any further questions please contact me.  Happy gardening.

Bob