APHIDS: Aphidae

ADULT: Corn in Florida is colonized by species of Rhopalosiphum. These are small to medium sized, eliptical to pear-shaped aphids with green bodies.  Their cornicles are swollen with a distinct constriction before the flared ends. The frontal tubercles (bumps between antennae) are not pronounced and are expanded only very slightly outward between antennae bases.

NYMPH: Winged or wingless adults directly produce live nymphs without eggs. They are similar in appearance to adults, only smaller.  They molt several times to reach the adult stage in 7 to 10 d.  Aphids have no pupal stage.

DAMAGE: Aphids feed within the corn whorl or on husks. They remove sugar-rich fluids to extract amino acids and proteins. Honeydew is produced to void excess sugar. Numerous fungi grow in honeydew giving it a sooty appearance (sooty mold). Honeydew and aphids are undesirable in silks and on ears and can result in lowered grade.

CONTROL: Natural enemies (predators and pathogens) can play a role in aphid control, particularly in fields with low pesticide pressure. However, the timing of predators and parasitoids arrival and their reproduction may allow large aphid populations to develop before control is realized. The corn whorl affords aphids some protection from chemical control as does the silk and leaf canopy for those feeding on husks. Pesticides are available for post-emergence foliar treatments. Formulations, rates, and pre-harvest intervals of insecticides for aphid control are listed below for sweet corn (Table 1) and field corn (Table 2).