Timing of Karner Blue (Lepidoptera: Lycaenidae) Larvae in Spring and Adults in Spring and Summer in Wisconsin During 1991-1998

During 1991-1998, formal surveys and incidental observations of the Karner blue (Lycaeides melissa samuelis) (Lepidoptera: Lycaenidae) occurred on 2-8 dates each year for spring larvae and on 5-10 dates in each adult generation at 148 pine-oak barrens in ten counties of central and northwestern Wisconsin. A total of 493 spring larvae were recorded, as well as 16,039 adults (6755 in spring and 9284 in summer) in 375.5 hours of formal adult survey effort. Adult Karner blue timing varied among years by about 2-5 weeks in spring and 2.5-6 weeks in summer. The mean span between spring and summer adult generations was about 46 to 50 days for all sites pooled. In some years, Karner blue phenology appeared to speed up or slow down relative to this average span between generations. At six sites surveyed for spring and summer adults in the same 5 years, the mean date of maximum adults differed among sites by about 9.5 days in spring and 6 days in sum­mer. These sites varied in the consistency of their relative phenology (early, average, or late) between spring and summer. Consistent sites changed relatively little in shading from spring to summer because canopy was sparse or primarily evergreen. Variable sites changed in degree of insolation between spring and summer, because of the leafing out of deciduous canopy or the higher angle of the summer sun rising above the surrounding forest more. Four kinds of variability should be considered in assessments of Karner blue phenology: (1) intergenerational fluctuations in abundance, (2) phenological differences among years and (3) among sites, and (4) interannual variation in span between spring and summer generations