CONEWORMS, Dioryctria spp.
Coneworms are perhaps the most destructive insect pests of pine cones in the South. They are particularly serious in superior-tree seed orchards where they frequently cause substantial economic loss. There are five important species of coneworms in the South, one or more of which attack all of the native and exotic pines.
Coneworm larva feeding on a pine shoot.
Although the number of generations per year varies with the species, their general life history is similar. Female moths lay their eggs around wounds, cankers, galls, etc., but also deposit particularly on terminal growth. Eggs generally hatch in about a week. Larvae may stay at a single feeding site, or move to several different sites before completing their development. This latter behavior often results in a single larva destroying several cones or shoots. Pupation takes place in a chamber constructed by the larva at the feeding site. Depending on the species and time of year, the adult may emerge in two to three weeks or overwinter in the pupal stage. Coneworms cause several kinds of damage. They may mine through the inner bark, bore up the center of a shoot, or completely hollow out a cone. Their attacks are sometimes marked by fecal pellets and large pitch masses.
Slash pine cone damaged by coneworm larva.
Several parasites attack coneworms but are seldom effective enough to prevent population build-ups. Chemical control is often necessary on seed orchards to ensure adequate protection of the cone crop.
PINE SEEDWORMS, Laspeyresia spp.
Until recent years little has been known about pine seedworms. These insects are found throughout the South but seldom have population explosions. An exception to this is on slash pine in Florida where over 70 percent of one year’s cones were reported infested. Longleaf pine cones in Texas and Louisiana have also had over 60 percent cone infestation on occasion. Loblolly and shortleaf pine cones are seldom over 20 percent infested. Seedworms have been found infesting longleaf, loblolly, shortleaf, slash, and Virginia pine cones. Laspeyresia anaranjada Miller attacks primarily slash pine, occasionally longleaf pine, and rarely loblolly pine. L. ingens Heinrick attacks primarily longleaf and slash pine. L. toreuta Grote attacks Virginia, shortleaf, and loblolly pine in the South.