Ugly, compact masses of brown excrement or frass pellets around the stem
of pine seedlings mark infestations of the pine webworm. Rarely is the
defoliation severe enough to kill the seedlings, but it undoubtedly has
an impact on growth. Found throughout the eastern United States, the
webworm commonly attacks red, white, jack, loblolly, shortleaf, and
slash pines.
[Illustration: Pine webworm damage to loblolly pine.]
[Illustration: (cont.)]
The adult moth has a wingspread of about one inch. The forewing usually
is gray in the middle portion and darker at the base and tip. The hind
wings and body are smokey gray. The full-grown larva is a caterpillar
approximately ⅘ of an inch long. The head is tan with darker markings
and the body light brown with dark longitudinal stripes running down
each side.
Eggs are usually laid on seedlings, occasionally on larger trees,
between May and September. After eggs hatch, the caterpillars live in
silken webs surrounded by masses of frass, and feed on the needles.
Generally each web contains one or two larvae but occasionally 25 or
more may be found. After feeding is completed, the caterpillars drop to
the ground and pupate below the soil surface. In the South, there are
usually two generations each year.
In plantations, hand picking is an effective method of control. When
high value nursery stock becomes infested, chemical control may become
necessary.