Orthosia hibisci Guenée (Lepidoptera: Noctuidae: Noctuinae)
We cannot definitely list Orthosia hibisci Guenée as an annual pest of hybrid poplar trees in Oregon and Washington. However, a major defoliation of older trees due to this pest in 2005 lead to an application of diflubenzuron (Del Pozo-Valdivia 2011) in May 2006 to target early instars. In 2008, we captured over 300,000 O. hibisci male moths with just one baited sex pheromone per 160 acres (65 hectares). After five years (2006–2011) of monitoring O. hibisci populations, we know that their numbers do increase within each planting as poplar trees age, and growers have a valid concern about their potential to defoliate trees. Our objective is to provide professional integrated pest management (IPM) managers with: a means to identify O. hibisci, a way of monitoring their numbers, and a means to control the population if necessary.
Three Noctuinae species have been pests of poplar in eastern Oregon and eastern Washington. In addition to O. hibisci, Spodoptera praefica Grote, the yellowstriped armyworm, and Noctua pronuba L., the winter cutworm, have all been recorded as defoliating pests of poplar. In the poplar farm, the most common species in the green fruitworm complex (Chapman and Lienk 1974; Rings 1975) is O. hibisci. Two additional fruitworm species (Amphipyra pyramidoides Guenée, Amphipyrinae, and Lithophane antennata Walker, Cuculliinae) are present in the Pacific Northwest area (Howell 2011), but they have not been captured in poplar plantations. These three fruitworm species were introduced from Europe in the 1800s (Chapman and Lienk 1974).
Speckled green fruitworm (SGFW) O. hibisci is commonly found attacking a large variety of trees and shrubs, including tree fruits and other woody plants within five plant families, especially Rosaceae and Salicaceae. This species mainly attacks apple, crabapple, pear, peach, apricot, plums, cherry, willow, birch, poplar, alder, and maple (Rings 1970; Chapman
Orthosia hibisci is found throughout moist deciduous forests, riparian zones, and agricultural and urban woodlots in northern latitudes from 35°N to 45°N (Rings 1970). Although more common east of the Great Plains states, it occurs in California, Oregon, and Washington (http://www.butterfliesandmoths.org).
Orthosia hibisci populations are univoltine. Adults emerge in February and mate. The forewings are grayish pink, with two mid-wing purplish gray spots, outlined by a narrow pale border (Figure 1). Females lay eggs, followed by six larval instars, and finally overwinter as pupae.
Eggs are about 0.8 mm, almost spherical with a slightly flattened top, and are deposited singly or in pairs on leaves.