Pine Cone Borers (Eucosma spp.)

Damage is similar to that of Dioryctria spp., but the riddled cones tend to be packed with a mixture of chewings and frass with no obvious tunnel system.

Shortleaf pine cone borer, Eucosma cocana Kearfott (6, 24, 26, 27, 44)

BIOLOGY. - The shortleaf pine cone borer has a single generation each year. Moths emerge from overwintered pupae in the soil and lay small overlapping groups of eggs under the scales of cone stalks in the spring (April-May). Young larvae feed in groups in immature cones, then disperse, tending to become more solitary in subsequently infested cones. Dispersal tends to be within a major branch system so that infested (or killed) cones within the tree crown are noticeably grouped. When mature (June-July), the larvae drop from the cones and pupate in the soil until the following spring.

INSECT IDENTIFICATION. - Larvae are light pink-purple with brown heads. Moths are mottled in orange-brown and silver.

Adult. (3X)

Larva. (3X)

DAMAGE IDENTIFICATION. - The first cones infested in the spring are usually peppered by small exit holes created by dispersing larvae. Subsequently attacked cones have oval entry-exit holes (2x3 mm) near the cone base together with small holes scattered along the cone surface where larvae break through the cone surface while feeding. Fine chewings and frass can be present on the surface of infested cones. The cone interior is riddled and packed with frass and chewings.

Damage to shortleaf pine cones. (1X)

IMPORTANCE. -This insect commonly infests shortleaf pine cones. Extent of damage is comparable to that of coneworms. On loblolly pine it occurs less frequently and is generally of minor importance.