The decline of the frosted elfin butterfly Callophrys irus population in the Rome Sand Plains of central New York is directly related to loss of its host plant, wild blue lupine, Lupinus perennis L., as Eastern white pines, Pinus strobus L., invade the open sandy habitats where lupines grow. A frosted elfin population remains where lupines are the densest. We tested the hypotheses that white pine canopy hinders lupine growth and restricts elfin behavior and abundance.  

Results/Conclusions

Removal of white pines from experimental plots in 2002 resulted in dramatic increases in canopy openness. Lupine flowering stems and lupine cover increased significantly in the tree removal plots and remained constant or declined in the control plots. The total number of lupine stems has decreased in both control and cleared plots, however. Male frosted elfin butterflies, which form mating territories in open sandy areas along tree-lined trails at the edges of lupine patches, established several new territories in the open patches where trees had been removed. The additional sites have been used for territories each year since tree removal, and the number of observations of frosted elfins in these sites has doubled. This rapid response by the butterflies reflects their behavioral choices for open areas. The abundance of frosted elfins also appears to have increased by at least half. Selective tree removal at the Rome Sand Plains benefits individual lupine plants and increases habitat for frosted elfin butterflies, but more extensive habitat manipulation may be necessary to increase lupine population numbers.