[Illustration: Fig. 10.—Rose chafer beetles on chestnut blossoms.]
Insects Attacking the Foliage
~Black pecan aphid.~ Pecan trees at times suffer sufficient damage from the black pecan aphid[15] to cause considerable defoliation (Fig. 5) during the latter part of the season. The injury to foliage in its earlier stages consists of irregularly shaped yellowish areas which turn brown when the tissues die.
[15] ~Melanocallis caryaefoliae~ (Davis).
This aphid is usually controlled with nicotine sulfate (40 percent nicotine), 3/8 pint plus summer oil emulsion, 2 quarts per 100 gallons of spray. Parathion and benzene hexachloride have given good results in experimental work but are not yet generally recommended.
~Pecan phylloxera.~ The pecan phylloxera[16] is related to aphids. It attacks principally the vegetative parts of the tree such as the leaves, petioles, and shoots on which galls (Fig. 6) are produced. Pecans, hickories, and other species of nuts are subject to infestation.
[16] ~Phylloxera devastatrix~ Perg.
In the past a spray of nicotine sulfate (40 percent nicotine) 13 ounces combined with either lime-sulfur solution, 2-1/2 gallons per 100 gallons of water, or lubricating-oil emulsion, 2 quarts per 100 gallons, applied in the late dormant period has been the standard recommendation. In recent experiments in the South with some of the new organic sprays, benzene hexachloride and some of the dinitro compounds have indicated good promise.
~Fall webworm,~[17] ~walnut caterpillar,~[18] ~and hickory tussock moth.~[19] The caterpillars of these species (Figs. 7, 8, 9) are frequent pests on the foliage of nut trees. They often defoliate entire branches.
[17] ~Hyphantria cunea~ (Drury).