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Zale perculta Franclemont, 1964Okefenokee Zale Moth
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G2?
State Rank: S2
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 4
Habitat Summary for element in Georgia: Cypress swamps
Zale perculta is one of the two largest species in the genus. The ground color of the forewings is a medium brown. The distinguishing feature of the adult (see photo below) is the pastel green antemedial band, similar coloration in the area of the reniform spot, and also along the subterminal area of both the forewing and hindwing. The wingspan of the species is around 6 cm (2.25 inches). The caterpillar (see above) is unmistakable, with no other species even remotely similar.
The only other Zale species that co-occurs with perculta that has greenish shading is Z. aeruginosa. Z. aeruginosa is a darker, almost blackish moth, and the greenish shading is reduced significantly on aeruginosa, though similarly located on the wings, compared with perculta. Z. aeruginosa is also a much smaller moth (3 cm or 1 5/8 inches wingspan). The only other Zale that is similar in size is the Lunate Zale (Z. lunata), but lunata has no greenish color anywhere and cannot be confused with Z. perculta.
The species is found in cypress swamps and wet areas near swamps, where the shrubs/vines of climbing fetterbush (see below) grow.
The larvae have only been found feeding on climbing fetterbush (Pieris phillyreifolia (Hook.)) (Ericaceae). Adults of Zale species are often attracted to fruit bait, but a bait trap put in the same location as a light trap that caught the most adults had NO specimens of the moth in it. So this moth seems more strongly attracted to lights than to fruit bait.The larvae have only been found feeding on climbing fetterbush (Pieris phillyreifolia) (Ericaceae). This plant typically grows as a vine at the base of certain cypresses (Taxodium spp.), Atlantic White Cedar (Chamaecyparis thyoides), and to a much lesser extent on some pines and oaks (Schweitzer, et al., 2011). The plant does, however, also grow as a free-standing shrub away from the trees, although typically close to the swampy habitats where its “host” trees occur.
Adults of Zale species are often attracted to fruit bait, but a bait trap put in the same location as a light trap that caught the most adults at Alligator Creek WMA in March, 2020 had NO specimens of the moth in it. As such, this moth seems more strongly attracted to lights than to fruit bait, although this experiment represents a sample size of one.
The known life cycle is one generation annually with caterpillars (see photo above) observed in April and May in Georgia (Durden, et al., 2020) on the known foodplant, Pieris phillyreifolia. The adults fly early in the year, from late February into late March.
Mature caterpillars collected by Lance Durden from Alligator Creek WMA in May of 2019 to observe pupation and emergence, burrowed into the soil to pupate, spinning a loose cocoon in the cell formed in the soil (Durden, et al., 2020). It would seem, however, that not all individuals would burrow in the soil to pupate, as the habitat where you find the species is often prone to flooding. It is possible that where the species occurs that larvae travel some distance before pupating in the soil or that pupae may be formed under the bark of trees.
This moth seems to be reliably found wherever large populations of Climbing Fetterbush occurs. Since this species is monophagous on the Climbing Fetterbush, to find additional populations of the moth it would make sense to target unsampled foodplant locations. Two Georgia counties with populations of the foodplant that had not been surveyed until very recently (2019) have been found to have populations of Z. perculta, which reinforces the idea that the moth may be more widespread than previously thought (Durden, et al., 2020).
The distribution and ecology of the species requires more research, but populations are known from Florida, Georgia and South Carolina. The distribution of the plant (see USDA PLANTS database) includes much of the panhandle of Florida, as well as the southern tier of counties in Alabama and extreme southeastern Mississippi, so it is possible that the moth will be found over much of the Floridian panhandle and extreme southern Alabama.
In Georgia, the counties associated with and around the Okeefenokee Swamp are the stronghold for the species. A large population of the moth and the foodplant has recently been found at Alligator Creek WMA in Wheeler Co. (Durden, et al., 2020).
This is a moth that is largely tied to moist to swampy areas, frequently with Cypress, that are often surrounded by sandy habitats. The stronghold of the Okefenokee Zale is, not surprisingly, the Okefenokee swamp and surrounding habitats, much of which is protected within the Okefenokee National Wildlife Refuge. The farthest north population so far found in Georgia is also on protected land in the Alligator Creek WMA in Wheeler County. As such, much of the range of this moth in Georgia is already protected. In places where it is not protected, swamplands are not under extreme danger from development, so this moth is probably not under major threat from humans. Perhaps the biggest threat would be from extreme weather events, either severe storms or drought, which could cause damage to the foodplants directly as well as changing the local hydrology in a manner that could impact the foodplants as well (Schweitzer, et al., 2011).
There are colonies of this moth in multiple locations in at least five counties in Georgia currently, and likely to be more where the foodplants have not been surveyed for the presence of the moth. As such, this moth should be S2, and maybe even S3, for the state of Georgia.
This is a moth that will likely thrive best by having the habitats with the foodplant, Pieris phillyreifolia (Climbing Fetterbush) left largely alone. During extreme drought, some individuals of the plants, especially those plants that grow in the shrub form away from the Cypress or other host trees, could possibly burn, which might be good for rejuvenation of the plant and its habitat, but not so for the moth, especially if it pupates up in the plant material. This could explain at least partly why some individuals pupate in the soil. If the habitats where the moth occurs are ever burned in a prescribed burn, then the prescribed burn needs to be done in a small patchwork format to allow for foodplant refugia for the moth to survive and recolonize the burned areas.
Durden, L. A., D. J. Stevenson, F. Snow, and J. K. Adams. 2020. Okeefenokee Zale Moth (Zale perculta Franclemont) (Erebidae): life cycle notes and newly discovered populations in Georgia, USA. Southern Lepidopterists' News 42(2): 121-126.
Gaddy, L. L. 2012. Zale perculta Franclemont (Erebidae) (the Okeefenokee Zale Moth) in South Carolina. News of the Lepidopterists' Society 54(2): 77.
Schweitzer, D. F., M. C. Minno, and D. L. Wagner. 2011. Rare, declining and poorly known butterfly and moths (Lepidoptera) of forests and woodlands in the eastern United States, pages 342-344. Forest Health Technology Enterprise Team.
US Department of Agriculture website. PLANTS database. Online at https://plants.usda.gov/java/
Anna Yellin, James Adams (professor of Biology, Dalton State College, Dalton, GA)
July 27, 2020