New Search
6) Scientific Name: Icaricia icarioides fenderi <br /> Common Name: Fender's blue butterfly <br /> Family: Lycaenidae <br /> Status: ONHDB List 1 (threatened with extinction throughout its range) <br /> State: no status <br /> Federal: Candidate <br /> Geographic Distribution: Though the common western blue as a species is widespread in <br /> western North America, I. icarioides fenderi is restricted to native upland prairies in the <br /> Willamette Valley of western Oregon. The Fender's blue is apparently most closely related <br /> to the Pardalis blue (Icaricia icarioides pardalis) of the San Francisco Bay area (Hammond <br /> and Wilson, 1992). There are twelve native prairie sites currently supporting the Fender's <br /> blue butterfly, located in Benton, Lane, Polk, and Yamhill Counties. There are only four <br /> sites that support populations that are large enough to be potentially viable over the long <br /> term. <br /> Habitat Description: The habitat of the Fender's blue is upland native prairie. It is <br /> essential that a site have a sufficiently large population of the larval host plant, Lupinus <br /> sulphureus ssp. kincaidii (or in a few sites outside of west Eugene, Lupinus laxiflorus). The <br /> other necessary site attribute is a sufficient abundance and diversity of nectar sources (see <br /> below), but an abundance of native grasses does not seem to be a habitat requirement. <br /> Species Description: The Fender's blue is a small butterfly with a wingspan of about 1 <br /> inch. The male butterflies are blue in color, while females are brown (in I. i. pardalis, a <br /> portion of the females are partly blue). The second row of black spots along the margin of <br /> the ventral side of the hind wing is present, but small and inconspicuous, rather than large <br /> and conspicuous as in I. i. pardalis. Also, the males have a silvery blue color, rather than <br /> the violaceous blue color if I. i. pardalis. The differences between these two subspecies and <br /> I. i. icarioides are discussed in more detail in Hammond and Wilson (1992). Another <br /> common blue butterfly in the Willamette Valley is the silvery blue (Glaucopsyche lygdamus), <br /> which has blue females, a much more evident second row of dots on the ventral hind wing, <br /> and reaches the peak of its flight season several weeks earlier in the spring than the Fender's <br /> blue. <br /> Life Cycle and Biology: Adult butterflies are active during May and June and lay eggs <br /> mainly on Kincaid's lupine, Lupinus sulphureus ssp. kincaidii and spurred lupine, L. <br /> laxiflorus (larvae have also been found feeding on sickle- keeled lupine, L. albicaulis, at one <br /> site). Newly hatched larvae feed for a short time until the second instar, when they enter an <br /> extended diapause that lasts until the following March or April at which time larvae become <br /> active again. Larvae are pure green without markings except for a faint, pale lateral line. <br /> 14 <br />