The Southern Pine Coneworm, Dioryctria amatella (Hulst)

The southern pine coneworm, Dioryctria amatella (Hulst), also commonly referred to as a pitch moth, is consistently one of the most damaging insect pests of pine seed orchard crops throughout the southeastern United States (Ebel et al. 1980). Less well-recognized is that this widespread and frequently occurring insect also attacks a variety of other parts of pines (Pinus spp.) besides cones. Caterpillars can be found feeding on and in buds, male and female flowers, shoots, branches and stems of all ages and sizes, as well as in conelets (i.e., first-year cones) and second-year cones (Ebel 1965; Ebel et al. 1980; Goolsby et al. 1972). The prevalence and variety of D. amatella infestations on forest and shade trees pines throughout the state periodically generates concern over the nature and impact of its injuries. The most noticeable symptom of infestations is large external masses of pitch (Fig. 1) exuding from the feeding sites of caterpillars, hence the name “pitch moth”. Reddish-brown frass may also be evident at feeding sites and is often mixed with resin. Pitch masses caused by D. amatella may resemble those of the black turpentine beetle (BTB ), Dendroctonus terebrans ( 0 liv. ); however, the coneworm pitch masses are usually larger, more irregularly shaped and flow for months. BTB pitch masses are typically less than 25 mm in diameter, have an obvious entrance hole, solidify in weeks, and are concentrated on the lower bole of large trees (Barnard and Dixon 1983; Goolsby et al. 1972). In addition to reproductive structures, susceptible host material includes: trees under stress, mechanically injured stems or branches, elongating shoots of longleaf (P. palustris Mill.) and slash pine (P. elliottii Englem.) during the spring, graft and branch unions, conelets infected with the southern cone rust fungus (Cronartium strobilinum (Arth.) Hedge & Hahn) and especially galls caused by the fusiform rust fungus ( Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme) (Barnard and Dixon 1983, Ebel et al. 1981, Goolsby et al. 1972). Other than the potentially significant losses that can occur in seed orchards due to the destruction of flowers, conelets and cones, damage is rarely severe or lethal to trees. The girdling effect of caterpillar feeding, however, can cause dieback of branches, terminals and tree tops (Fig. 7), and additional weakening of previously damaged stems (Barnard and Dixon 1983). Feeding injuries also serve as infection courts for the pitch canker fungus, Fusarium subglutinans (Wollenw. and Reinking) Nelson, Toussoun and Aarasas (Foltz and Blakeslee 1989).