High concentrations of eye gnats are common in areas that have loose sandy soils, especially in the southern United States, and are a great nuisance to humans and animals in rural towns as well as agricultural, recreational, and tourist areas. While they do not bite, they can transmit several diseases to humans and livestock, including human acute conjunctivitis (pink eye). This 6-page fact sheet focuses broadly on two species that are common in the southeastern region of the United States are L. pusio and L. bishoppi (Sabrosky). Written by Erika Machtinger and Phillip E. Kaufman and published by the UF Department of Entomology and Nematology, April 2011.
http://edis.ifas.ufl.edu/in884