Feeding by the insects after shell hardening, Figure 14, produces brown or black spots on the kernels. Areas affected taste bitter, but the remainder of the kernel is unaffected.
Stink bugs are familiar to everyone. Plant bugs resemble them and are usually shades of brown, smaller and narrower in body outline.
Plant bugs and stink bugs overwinter in the adult stage in debris on the ground. In the spring, the adults are attracted to growing vegetation such as cover crops or weeds, where they deposit their eggs. The immature bugs develop on low-growing vegetation. When they reach maturity, their wings are fully developed and they fly to pecan trees. A few eggs may be deposited on pecan trees, but the young bugs apparently are unable to develop on them. Only the adults are present in sufficient number to inflict economic injury. There may be as many as four generations each year.
_Control._—Although certain insecticides will control these pests, the number and frequency of spray applications necessary for control would not be economical.
Care should be taken to keep weeds down in the orchard during the growing season. Winter cover crops should be plowed down early in the spring so they will not be attractive to the adults coming out of hibernation. If this operation is delayed, the bugs will leave the cover crop when it is removed and migrate to the trees in large numbers.
These soft-bodied insects appear during the summer and fall. They suck the sap from the leaves, causing them to turn yellow or brown and fall to the ground. Heavy infestations may cause defoliation in the late summer reducing the nut crop in the current and succeeding year.
The black pecan aphid, _Melanocallis caryaefoliae_ (Davis), is about one-sixteenth inch long when full grown, robust and greenish black. Its back is decorated with tubercles.
Bright yellow blotches up to one-fourth inch in diameter appear around the punctures produced by the feeding of this insect.
The yellow aphids, _Monellia_ spp., which attack pecans inflict injury similar to that caused by the black pecan aphid. However, the large yellow blotches on the leaves do not result from their feeding. A sticky substance called “honeydew” is secreted by these insects creating an ideal medium for sooty mold fungus to develop[5].