CORN DELPHACID: Perigrinus maidis, Delphacidae
ADULT: These planthoppers are yellowish-brown with darker brown markings along the edges of body segments. The front of the head is punctuated by a central, elevated ridge. Compound eyes are bead-like and arise from within cavities on the side fo the head. Antennae are elbow-like and usually face backward. Both short- and long-winged forms exist, with gray to black markings along the back edge of the fore wings. Hind tibia are folded forward under femora in preparation for jumping. There is a large flattened spur at the apex of the hind tibia.
EGG: The short (1/32 in. long), thin whitish eggs are inserted into plant tissue, such as corn leaf midribs. The red eye spots of the enclosed developing nymphs are visible within a day of emergence.
NYMPH: Nymphs pass through five to six instars (sometimes as few as four) during their development. The first four instars are white with the fifth instar taking on more yellow base color and brown markings along the margins of the body segments. Wing pads begin to develop externally with the fourth instar. The second antennal segments and spurs at the end of the tibia on the rear pair of legs become larger and more pronounced with proceeding instars. There is no pupal stage in delphacids.
GENERATION TIME: 22 to 30 d.
DAMAGE: P. maidis is found throughout Florida. Feeding damage by this insect is possible with large populations, but the major threat is through transmission of maize stripe virus (MStpV) and maize mosaic virus. These viruses cause obvious yellow discoloration of the leaves, stunting and reduced ear production.
CONTROL: Spiders consume large numbers of delphacids, leafhoppers and planthoppers on corn. Pesticides are available for foliar application to control these pests, but their impact on the control of primary virus infection is questionable.