Bionomics of Eucosma monitorana (Lepidoptera: Tortricidae) attacking red pine cones in Wisconsin
A localized infestation of Eucosma monitorama Heinrich was studied in 1963 and 1964 in southern Wisconsin. Adults are secretive, weak flyers but several were collected in May with sticky trap-boards and light traps. Adult emergence and flight occur at time of red pine pollen release. Eggs were not found in macro- and micro-scopic examinations of cones, twigs, and needles. Larvae were active from early June through July. External symptoms of cone attack developed slowly, but the interior deteriorated rapidly. A standardized examination for 300 cones revealed that most attacks by migrating larvae were in the mid-ventral surface. Pupation occurred in the soil in late June and the pupae period lasted to the following may. Sexual dimorphism in the pupae was discovered and illustrated. The pupal stage is characterized by a winter diapause which was difficult to artificially interrupt. Attack was unequal between trees, but was random within crowns. As the season progressed, the percentage of newly attacked cones in the top and middle crown. This increase apparently resulted from the availability of more unattacked cones in the top and middle. An unidentified Apanteles sp. was found parasitizing E. monitorana larva. Death of the host larvae occurred during the 3rd stage.
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