Ask Mr. Smarty Plants

Mr. Smarty Plants assumes that you have pinpointed violets as the plants that harbor mosquitos.  They do have broad leaves growing close to the ground, where they will retain moisture.  Mosquitos will also hide in other humid locations, such as a dense cluster of ferns.  I suggest that you replace the violets with plants that send their stems higher and/or have few or small leaves near ground level.  For example, Aquilegia canadensis (Eastern red columbine), Packera aurea (Golden ragwort), Lobelia cardinalis (Cardinal flower) and Symphoricarpos orbiculatus (Coralberry). There are many other plants to choose from, depending upon your conditions, e.g. full shade, part shade, moist, dry, need for low-growing or taller species.  Grasses generally do not do well in shade, but you could use a sedge, such as Carex pensylvanica (Pennsylvania sedge).  This would look nice interspersed with other short species like Mitchella repens (Partridgeberry), .  Ferns should do well.  If taller plants are desirable, consider Hypericum prolificum (Shrubby st. johnswort), Maianthemum racemosum ssp. racemosum (Feathery false lily of the valley), Maianthemum stellatum (Starry false lily of the valley), and Lobelia siphilitica (Great blue lobelia).  Symphyotrichum novae-angliae (New england aster) should thrive in partly sunny areas.

Certain plant species have been shown to have insect-deterrent activity.  Most of those species I found are not native to your area.  The sages generally occur naturally further west, but one species, Salvia azurea (Pitcher sage), is native to Virginia, and it may have unreported deterrent properties.