This insect overwinters in the pupal stage in the soil. The adult emerges in the spring and deposits eggs in masses on the underside of the leaves, [Figure 20]. The larvae feed in colonies on the leaves for about 3 weeks. At periodic intervals, the groups of larvae move to the trunk to molt and, after shedding their skins, they return to the leaves to feed until the next molt. They do not encase themselves in webs. There are two generations each year, the first appearing in late spring and early summer, the second in later summer and fall. Larvae of the second generation complete development and crawl down to pupate in the soil.
Control.—When these insects become abundant enough to defoliate portions of the tree, they may be controlled by applying a spray containing 2 pounds of 50 percent DDT wettable powder; 3 pounds of lead arsenate; or 1 pound of 25 percent parathion wettable powder per 100 gallons of water.
Figure 20. Walnut caterpillar adults and egg mass on a pecan leaflet.
PECAN CATOCALA
Several species of catocalas, [Figure 21], among them Catocala maestosa Hlst., may strip the leaves of pecans in the spring leaving only the midribs. The caterpillars are very dark gray and attain a length of about 3 inches when full grown. They are very active when disturbed and move with a looping motion. Both the caterpillars and the moths are well camouflaged. When they rest on the trees during the day, their color so harmonizes with the color of the bark that they are frequently indistinguishable.
Control.—One application of 2 pounds of 50 percent DDT wettable powder per 100 gallons of water controls this pest. Although the majority of catocala larvae reach maturity before the time to spray for the nut casebearer, a number of them will be killed when the recommended spray is applied for the latter insect.
PECAN SPITTLEBUG
In the spring and early summer a number of buds and small nuts may be covered with foamy white masses. Inside these masses are several small insects called spittlebugs, Clastoptera obtusa (Say). The white froth is produced probably to maintain an artificial high humidity, which is required for development. The adults resemble leafhoppers and fly actively during the summer.
This insect has not been known to cause any significant injury on pecans in Texas.