Corn leaf aphid
- Adult: Bluish-green or gray round, soft-bodied insect about the size of a pinhead. They appear in clusters in the leaves and upper cornstalk. Some females have filmy wings. Aphids secrete a sticky sugary substance called honeydew.
- Nymphs: Look similar to the adults but smaller.
- Eggs: Females do not lay eggs but give birth to live young.
Timing of damage: V6 to R1
Type of damage: Wilted, curled and yellowed leaves. Tassels and silks may be covered with honeydew, which can affect pollination.
Scouting: Examine the whorls of 20 plants in five locations (for a total of 100 plants). Note the number of aphids per plant.
Economic threshold: Treat if 50% of plants have more than 100 aphids per plant and the plants are under stress.