Sooty mold often develops on pecans following a heavy aphid infestation. Yellow aphids are characteristically yellow in appearance. Shiny, polished, black, parasitized yellow aphids are often confused with the black pecan aphid. Damaging infestations of yellow aphids can cause whole leaves to turn yellow and possibly shed. Black aphid damage is characterized by small, chlorotic areas on the leaflets.
Heavy infestations cause rapid leaf shed.
Both aphids can cause premature leaf shed, reduced nut quality, and subsequent yield reductions the following season. Black and yellow pecan aphids have very similar life cycles. Both overwinter as eggs. Wingless females hatch in March and migrate to the newly emerging pecan leaves. These females in turn give birth to living young without mating.