Variation in timing and abundance of elfins (Callophrys) (Lepidoptera : lycaenidae) in Wisconsin during 1987-1999

In Wisconsin during 1987-1999, we recorded elfin (Callophrys) individuals o n 154 of 254 observation dates between 2 April and 11 July. The frosted elf in (C. irus) occurred only in central Wisconsin; brown (C. augustinus), hoa ry (C. polios), and Henry's (C. henrici) elfins in central and northern Wis consin; and eastern pine (C. niphon) from southern to northern Wisconsin. M ost individuals were eastern pine elfins, which occurred at the most sites, while Henry's elfin had the fewest individuals and sites. All five elfins occurred in the most frequently visited subregion (central Wisconsin), wher e they all had similar median and mean observation dates for all study year s pooled. For most elfins, the number of individuals observed per year cova ried significantly with the span of days between first and last observation dates that year. Within species, mean and median observation dates in the earliest year(s) always occurred before the first observation date in the l atest year(s). We compared the phenology of the frosted elfin flight period to the timing of olympia marble (Euchloe olympia) adults and spring Karner blue (Lycaeides melissa samuelis) larvae and adults. The least variable re lationship was the date of first mature Karner larva (typically before firs t frosted elfin adult, and bracketing that date by only 8 days). Only the f rosted elfin showed a significant influence of weather (temperature only) o n observed density, while most elfins significantly increased the nearer to noontime. We recorded elfins in broad ranges of weather conditions and dai ly timing. Elfin abundance fluctuated markedly among years based on the mea n of peak survey totals at the same monitoring sites in central Wisconsin e ach year from 1992 or 1993 to 1999. One "outlier" site each for frosted and eastern pine elfins had much higher peak survey totals than the other site s. Abundance fluctuations in the outlier and other sites did not correlate significantly for either species. For most elfins, the percent sites where the species was recorded as present each year covaried significantly with t hat year's annual mean of peak survey totals. This indicates that the abili ty to document presence of an elfin relates to the species' abundance that year. Since elfin abundance and flight timing and length varied considerabl y among years, the appropriate time for elfin detection must be determined individually for each year and assessments of an elfin's status and abundan ce cannot be reliably based on surveys at only a few sites or in a few year s.