The National Insect Collection was searched for specimens of Mecoptera collected on or near Plummers Island, Montgomery County, Maryland, and the records were taken from those found. A special effort was made in 2004 and 2005 to collect insects on or adjacent to Plummers Island, using a number of techniques. In addition to the usual ultraviolet light traps, two Malaise traps were operated during the season in 2005. Eleven species of Mecoptera were identified from this material: nine taken in the 1900s and three in 2004–2005. They belong to four families and four genera. Most are species widely distributed over eastern North America, and none is considered endangered.