CORN BLOTCH LEAFMINER: Agromyza parvicornis, Agromyzidae
ADULT: Small (1/8 in.), shiny black flies with clear wings. The area between the compound eyes above the antennae and below the simple eyes is brown, nearly twice the diameter of an eye and projecting above the surface of the eyes. The third antennal segment is pale brown. The second long segment of the legs (tibia) is brownish.
EGG: Female flies deposit eggs into leaf tissue. Larvae emerge in 3 to 4 d.
LARVA: Maggots emerge from eggs directly into leaf tissue and begin to feed. Larvae form large blotchy mines rather than the thin serpentine mines of vegetable or serpentine leafminers. Larvae complete development in 7 to 12 d.
PUPA: Larvae pupate within their leafmines. Maggots do not molt out of their last cuticle, but complete metamorphosis within it. The resulting delicate puparium is medium to dark brown. Adults emerge in 7 to 10 d.
GENERATION TIME: 17 to 26 d.
DAMAGE: This species is apparently distributed throughout North America. Leafmines weaken the leaves and provide easier access for bacterial and fungal diseases. Damage in fields is usually very limited. Large populations that lead to economic losses are rare, but have been noted in north and central Florida.
CONTROL: There are no pesticides currently registered for use against this insect.