Loblolly pine coneworm, Dioryctria merkeli Mutuura & Munroe ⁷ (8, 24, 27, 41, 52)

BIOLOGY. - The loblolly pine coneworm has one generation per year. Young larvae overwinter, then infest flowers and shoots. Some larvae complete development in shoots in slash and longleaf pines; others migrate into cones. In loblolly, shortleaf, and Virginia pines, most, if not all, larvae finish feeding in the cones. The mature larvae remain inactive over the summer, and pupation and adult emergence occur from August to October.

INSECT IDENTIFICATION. - Mature larvae of the loblolly pine coneworm resemble the southern pine coneworm but are dark bluish-black above and blue-green beneath.

The moths are also similar to those of the southern pine coneworm, but the base color of the forewing tends more toward a medium brown with irregular patches of rust-brown. The crossbanding and other pale markings are grayish, subtly blending into medium brown.

Larva. (2X)

Adult. (2X)

DAMAGE IDENTIFICATION. - Damage to flowers, shoots, and cones by the loblolly pine coneworm resembles closely that of the southern pine coneworm. Spring and early summer cone infestations on loblolly, shortleaf, and Virginia pines may be attributed to the loblolly pine coneworm, but damage by the two species cannot be separated on slash and longleaf pines.

Damage to loblolly pine conelet. (1 1/2X)

Damage to loblolly pine cone. (1X)

IMPORTANCE. - Shoot attacks followed by cone infestations are common, particularly on loblolly pine. On this species, the loblolly pine coneworm seems to approach the southern pine coneworm in importance.

⁷ This has appeared in the literature as D. zimmermani (Grote) in previous reports from the Southeastern United States.