Both black and yellow aphids overwinter in the egg stage in crevices in the bark. In the spring the eggs hatch, and the aphids begin feeding on the leaves. Many generations are completed each year. Only females, which may be wingless or winged, are produced during the growing season. The winged individuals fly to different parts of the tree or to other trees. In the fall, males and females appear and eggs are deposited under the bark.
[Illustration: Figure 13. Pupa of the second generation of the pecan nut casebearer in a hollowed out nut.]
Usually, these insects are not present in sufficient numbers to cause serious injury until mid or late summer. Infestations earlier in the season rarely assume damaging proportions. As is the case with mites, aphid populations may increase, following the application of certain insecticides applied for the control of the pecan nut casebearer or following treatment with bordeaux mixture for pecan scab disease control.
[Illustration: Figure 14. Southern green stink bug on developing nuts.]
_Control._—When damaging infestations appear, the trees should be sprayed with either 1 pound of 12 percent gamma BHC wettable powder; or 1 pint of 40 percent nicotine sulfate plus 3 pounds of soap; or 1 pound of 25 percent parathion wettable powder[9].
These tiny pests attack the leaves usually on the underside causing irregular brown areas to appear. Trees which are heavily infested appear scorched and may lose their leaves in late summer or fall.
Mites usually are light green and are just large enough to be seen without the aid of a hand lens. They are wingless and feed principally on the underside of the leaves along the midrib. Colonies of them produce webs in which molted skins and eggs may be found. The life cycle of mites is very short and several generations occur each year. Large populations may develop during the late summer and fall.
The use of certain insecticides for the control of the pecan nut casebearer or bordeaux mixture for scab control frequently contributes to increases in mite populations later in the season.
_Control._—Mites may be controlled in three ways when damaging infestations develop. An application of 2 pounds of wettable sulfur per 100 gallons of water may be made; 6 pounds of wettable sulfur per 100 gallons of water may be added to the spray applied for the control of the nut casebearer; and repeated applications of zineb included in a regular spray schedule for pecan scab control will effectively control mites. However, a single application of zineb is not effective[7].