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SPECIES. - In the South, three species, the slash pine seedworm, L. anaranjada Miller; the longleaf pine seedworm, L. ingens Heinrich; and the eastern pine seedworm, L. toreuta (Grote), are known to destroy seeds of one or more of the major southern pine species. Damage is caused by larval feeding and development within maturing seeds or cones.
BIOLOGY. - The biology of all three species is similar except for the time of adult occurrence. There is only one generation per year. In the spring the adult moths emerge and mate, and the females lay eggs on the cones. The eggs hatch in 3 to 6 days and the young larvae bore into the cones. Each young larva enters a seed and completely consumes the endosperm. The larva then bores its way to another seed, leaving the excrement-filled, hollowed seed behind. Each larva consumes from five to seven seeds during development. In the fall, the mature larva bores to the cone axis where it overwinters. The following spring the seedworm cuts an exit hole through a hollowed seed, neatly webbing the cut "cap" in place. It then pupates within its cone gallery. The pupa wriggles to the exit hole just prior to moth emergence and displaces the "cap." The moth then emerges from seed held between the cone scales of an open cone.
INSECT IDENTIFICATION. - Larvae and pupae of the three species of seedworms are not easily separated. The larvae are whitish with yellowish-brown heads. They are about 1 cm long when mature. The longleaf and eastern pine seedworm moths are almost identical. Both species have dark, slate-gray forewings with several silvery-white crossbars that are typical of the genus. The crossbar of scales on the tip of the forewing of the longleaf pine seedworm parallels and touches the margin of the wingtip. The outer crossbar of scales on the eastern pine seedworm parallels the wingtip margin but does not touch it. Moths of the slash pine seedworm can be easily identified by the orange color of the forewings.
Larva and pupa in axis of loblolly pine cone. (1X)
DAMAGE IDENTIFICATION. - There is no external evidence on cones attacked by seedworms. At cone maturity, most damaged seeds remain firmly stuck in the open cones. Damaged seeds are tightly packed with excrement and have larval emergence holes. They are readily identified on a radiograph. The larval galleries in the cone axis can be exposed by bisecting the mature open cone. Counting these galleries is a convenient method of assessing infestation levels.
IMPORTANCE. - Seedworm damage varies considerably among host species. Longleaf pine seed losses up to 40 percent have been recorded. Seedworm damage to seed of other pines is generally minor.
(4.5X) 18.5 mm
(6X) 14 mm
(5X) 15 mm