Analysis of Forest Tent Caterpillar, Malacosoma Disstria Hbn. (Lepidoptera: Lasiocampidae), Populations in Louisiana.

The forest tent caterpillar (FTC), Malacosoma disstria Hbn. (Lepidoptera: Lasiocampidae), has caused noticeable defoliation to tupelo gum, Nyssa aquatica L., in southern Louisiana since 1948. This species has a tremendous population growth potential and in epidemic years can totally exceed its host foliage resource. FTC egg hatch in Louisiana occurred after an average of 1,284 degree days using a beginning overwintering period of December 1 and a threshold temperature of 4.4(DEGREES)C 40(DEGREES)F). Larval development proceeded through five instars in Louisiana. Adult emergence and egg oviposition was completed by the second week in June. Two species of egg parasitoids, Ooencyrtus clisiocampae (Ashmead) and Ablerus clisiocampae (Ashmead), were responsible for 96.8% of the total FTC egg mortality. Analysis of partial life tables developed from three study sites over two field seasons revealed that generation survivorship was 1.1%. Frass traps were found to be valuable means of indexing within generation FTC population changes. Larval and pupal parasitism varied between sites and years with Sarcophaga houghi Aldrich being the only parasitoid responsible for consistent and significant FTC mortality. Two conceptual FTC defoliation models were constructed to predict defoliation by the FTC. The Forest Land Manager Model predicts over broad population classes utilizing a minimum of data. The Forest Pest Management Model requires several subsystems developed in this dissertation to be useful in predicting defoliation. Variances of all estimates are necessary for this model to function