On occasion, this insect, _Acrobasis juglandis_ (LeB.), develops to
damaging numbers and causes economic injury. Early in the spring the
larva feeds on unfolding leaves and buds. It may prevent leaf
development for weeks, resulting in a greatly decreased yield of nuts.
The adult is a dark gray moth marked with brown. Its forewings, which
have a spread of about two-thirds inch, are gray with black blotches.
There is a reddish mark near the base of the forewings.
The immature larva is brown, but changes to dark green as it develops to
a length of one-half inch. It has a shiny, brownish black head and is
enclosed in a gray case which completely covers the body and is borne in
a position nearly perpendicular to the leaf on which the larva is
feeding.
The pecan leaf casebearer overwinters as an immature larva in a
hibernaculum around a bud. It emerges in late March or early April as
the buds open. The larvae mature in April, May and June and transform
into pupae within their gray cases, Figure 15. The moths are present
from May until early August. Eggs are deposited during this period on
the underside of the leaves. The larvae which hatch from these eggs
develop slowly, and do not attain a length of more than one-sixteenth
inch during that season. They construct little winding cases in which
they live. Their feeding produces irregular blotches on the leaf
surface, Figure 16. Before the leaves drop in the fall, the larvae
migrate to the buds, and construct their overwintering hibernacula. Only
one generation is completed each year.
_Control._—Control of this insect is accomplished by spraying for the
pecan nut casebearer. See spray schedule, page 4. The insecticides
recommended for nut casebearer control also reduce infestations of the
leaf casebearer.
[Illustration: Figure 15. Overwintered larvae of pecan leaf
casebearer in their cases.]
[Illustration: Figure 16. Summer injury to the leaves by the pecan
leaf casebearer.]