The Karner Blue, Lycaeides melissa samuelis, is a small, blue butterfly found in small areas of New Jersey, the Great Lakes region, southern New Hampshire, and the Capital District region of New York. The butterfly, whose lifecycle depends on the wild blue lupine flower (Lupinus perennis), is classified as an endangered species. In May 2000, the Canadian Species at Risk Act listed the Karner Blue as being extirpated in Canada. This subspecies of Lycaeides melissa was described by novelist Vladimir Nabokov. It is sometimes placed in the genus Plebejus.
Local conservation efforts, concentrating on replanting large areas of blue lupine which have been lost to development (and to fire suppression, which destroys the open, sandy habitat required by blue lupine), are having modest success at encouraging the butterfly's repopulation. The Karner Blue, (Lycaeides melissa samuelis), is the official state butterfly of New Hampshire. The Necedah National Wildlife Refuge in central Wisconsin is home to the world's largest population of Karner Blues, who benefit from its vast area of savannah and extensive lupine.
The Karner Blue was first identified and named by novelist and lepidopterist Vladimir Nabokov. The name originates from Karner, the former name of Center, New York (located half-way between Albany and Schenectady, New York, in the Pine Bush), where it was first discovered. Lupine blooms in late May. There are two generations of Karner Blues per year. The first in late May to mid June. The second from mid-July to mid-August.
In the novel Pnin, Nabokov describes a score of Karner Blues without naming them.
The Karner blue butterfly occurs in isolated populations in eastern Minnesota, Wisconsin, Indiana, Michigan, and New York. Reintroductions have been initiated in Ohio and New Hampshire. The Karner blue butterfly appears extirpated from Iowa, Illinois, Pennsylvania, Massachusetts, Maine, and Ontario.
Although Karner blue butterflies are characteristic of oak (Quercus spp.) savannas and pine (Pinus spp.) barren habitats, they also occur in frequently disturbed areas such as rights-of-way, old fields, and road margins. In east-central New York, Karner blue butterflies occurred in 3 rights-of-way habitat types: wild lily-of-the-valley-starflower (Maianthemum canadensis-Trientalis borealis), sweetfern-whorled yellow loosestrife (Comptonia peregrina-Lysimachia quadrifolia), and blackberry-sheep sorrel (Rubus spp.-Rumex acetosella). An index of Karner blue population size was highest in the wild lily-of-the-valley-starflower type. In this habitat, mosses (Bryophyta, 6.9%), wild lily-of-the-valley (4.4%), grasses (Poaceae, 4.4%), and starflower (2.1%) had the highest cover. Coverage in the sweetfern-whorled yellow loosestrife type was dominated by grasses (40.9%), sweetfern (12.1%), mosses (9.4%), and whorled yellow loosestrife (5.2%). In the blackberry-sheep sorrel type, the dominants included grasses (22.7%), northern dewberry (Rubus flagellaris, 5.0%), other blackberries (4.8%), and sheep sorrel (4.3%).
Many other factors may influence the quality of wild lupine (Lupinus perennis) as a Karner blue butterfly food resource. At Indiana Dunes National Lakeshore, wild lupine with Karner blue butterfly feeding damage had significantly larger leaves and longer and thicker stems than plants without feeding damage . In addition, larval length was positively associated with wild lupine height in central Wisconsin . Higher nitrogen concentrations in wild lupine leaves resulted in significantly shorter larval durations in a feeding trial . In 1995 in west-central Wisconsin, significantly more Karner blue butterfly larvae were observed in oak-pine barren plots where mildew infection was delayed compared to areas where wild lupine were infected earlier. However, in a feeding trial larval duration of Karner blue butterflies fed mildew-infected wild lupine was not significantly different from treatments that resulted in the shortest larval durations. Karner blue butterfly fed water-stressed wild lupine had significantly longer larval durations than many treatments including larvae fed flowering wild lupine, shade-grown wild lupine in seed, or mildew-infected wild lupine . Although Karner blue butterflies have been shown to benefit from their association with ants, wild lupine with Karner blue butterfly larvae in the Allegan State Game Area in Michigan were not detectably closer to ant hills than wild lupine without caterpillars.
Adult Karner blue butterflies' preference for open, sunny areas has been well documented. Increased lupine and nectar abundance, higher temperatures allowing for longer activity periods, and ease of finding mates have been suggested as possible reasons for adult preference of open areas.
Adult Karner blue butterfly females are more likely to use shaded habitats than males. Avoiding harassment by males and compromising between greater amounts of wild lupine in open areas and better quality of wild lupine in shaded areas see below) have been suggested as possible reasons for increased occurrence of females in shade.
Differences between broods have also been observed. In west-central Wisconsin, abundance of spring adults positively correlated with decreasing canopy cover, while correlation with summer adults was very weak. At Indiana Dunes National Lakeshore, cover at late summer oviposition sites was significantly higher than at late spring oviposition sites. In Wisconsin and Minnesota, late spring oviposition sites occurred in partial and closed habitats significantly more than expected based on the number of nectar flowers and the cover and number of wild lupine stems, while summer oviposition sites did not differ significantly from expected. The different brood responses to shade may be due to the direct impact of varying environmental conditions over the course of the season on Karner blue butterflies (see Temperature) and the associated effects on wild lupine (see below).
Larvae in shaded habitat apparently have an advantage over those in open areas. The increase in larvae in shaded habitats is likely due to effects of shade on wild lupine.
Shade-grown wild lupine has been shown to provide higher quality larval resource than sun-grown lupine. Several reasons for this have been suggested. An often cited reason for the dependence of larvae, especially 2nd-brood larvae, on shaded habitat is the possibility of early senescence of wild lupine in open areas resulting in a lack of larval food [19,37,40,43]. Shade-grown wild lupine being more nutritious, possibly due to nitrogen content limiting photosynthesis to a greater extent in open areas, was one of several explanations. The size of wild lupine has been positively associated with Karner blue butterfly larval length  and amount of feeding damage. In addition, there may be shade-related effects on Karner blue butterflies that are related to the density of wild lupine. Wild lupine are typically more abundant in open areas than in shade . Mildew infection of wild lupine may be increased in denser wild lupine patches. Lower mildew infection rates in shadier areas have been reported . However the implications of mildew infection on Karner blue butterfly are uncertain (see Wild lupine). It has also been suggested that the low density of wild lupine in shadier habitats could provide better larval habitat due to the increased search effort required by predators [37,43]. This trade-off between lupine quality and quantity is another reason heterogeneous habitat is important for Karner blue butterfly .
On sites in Wisconsin and Minnesota, canopy cover did not have a significant (p>0.06) effect on total numbers of ants, parasitoids, or predators. However, certain species did show trends across canopy cover categories. For instance the ant Formica nitidiventris was only seen in open (≤15% cover) areas, while another ant, Dolichoderus plagiatus was only observed in areas with a dense canopy (≥76% cover). Parasitoids in the genera Phaeogenes and Orthostigma were all seen in closed habitats, while 90% of damsel bugs (Nabicula subcoleoptrata), a potential predator, were observed in open areas. Closed habitats had insignificantly (p=0.116) more parasitoids on average than partial (16%-75% cover) and closed habitats .
Other habitat characteristics: Although Schweitzer  asserts that the presence of litter is important to Karner blue butterflies in some years, abundance in a right-of-way in west-central Wisconsin was negatively (p<0.05) related with average litter cover .
In west-central Wisconsin, the amount of Karner blue butterfly larval feeding damage increased with grass cover . A review suggests that grass cover may provide roosting sites for Karner blue butterflies and that 5% cover of tall grass would most likely meet this need .
The effect of temperature can influence the occurrence of Karner blue butterflies in habitats of varying canopy cover . The lower temperatures occurring in partial and shaded habitats of Wisconsin and Minnesota meant that 1st-flight females only had access to these areas for a few hours a day. In contrast, these females could access open habitats an average of 10.5 hours a day. The percent of adults in habitats of varying canopy categories was significantly (p=0.0001) influenced by temperature, with butterflies, especially females, increasing in partial (15-75%) and shaded (>75%) habitats with increasing temperature. In addition, 80% (n=45) of 1st-flight ovipositions when temperatures were cool (68-79 °F, 20-26 °C) were in sun, while only 40% (n=17) of 1st-flight ovipositions in hot temperatures (86-97 °F,30-36 °C) occurred in the sun. The same trend was observed in 2nd-flight ovipositions. In cool temperatures 65% (n=11) of ovipositions occurred in the sun, while in hot temperatures only 40% (n=37) occurred in the sun .
Temperature also influences Karner blue butterfly phenology and brood success. Weather had strong influence on Karner blue butterfly phenology at Fort McCoy in west-central Wisconsin. In a cool year the 2nd-brood flight began 6 June, while in a warmer year adults were 1st detected on 22 May. In addition, compared to the previous year the flight of the 2nd-brood during the hot year was shortened by 20 days . At Indiana Dunes National Lakeshore, evidence suggests that cool winters negatively impact1st-brood populations and cool summers positively affect 2nd-brood populations . A review suggests that the cover provided by snowpack protects Karner blue butterfly eggs from hatching prematurely or being overheated by direct sunlight. Therefore, short periods of continuous snow cover due to site conditions or mild winters could result in decreased occurrence or smaller populations of Karner blue butterflies .
Size of habitat patches can also influence Karner blue butterfly abundance (see Wild lupine). At the Allegan State Game Area, wild lupine patches occupied by Karner blue butterflies were larger than unoccupied patches . This was also the case at Fort McCoy in Wisconsin . In addition to the effect of amount of wild lupine, a review  suggests that it is easier to maintain Karner blue butterfly habitat in larger patches. Lane  notes the need to find a balance between having patches of different required habitats within the activity range of Karner blue butterflies and having open areas large enough that they do not become shaded too quickly. Canopy openings with diameters of at least 82 feet (25 m) were recommended based on research at Indiana Dunes National Lakeshore , and research in Wisconsin and Minnesota led to a recommended opening size of 1.5 times the height of adjacent trees . According to a review, subpopulations in habitat patches of less than 0.25 ha (0.62 acres) are vulnerable to extirpation .
The presence of dispersal corridors may assist with Karner blue butterfly dispersal. Karner blue butterflies appear to disperse further in open habitats (see Timing of Major Life History Events). However, there is uncertainty regarding what constitutes a corridor or a barrier to dispersal . Creation of corridors with both lupine for larvae and nectar species for adults may be useful in connecting habitat patches [2,72].
Karner blue butterflies have two broods per year, following wild lupine (Lupinus perennis) phenology quite closely [10,63]. Eggs laid by Karner blue butterflies in late summer overwinter and hatch in mid- to late April. Development from egg through four larval instars and [[pupation] takes from 25 to 60 days. The average lifespan of adult Karner blue butterflies has been reported at between 3 and 5 days. The first Karner blue butterfly flight generally occurs sometime between mid-May and mid-June, with males typically appearing earlier than females. First flight females lay the vast majority of their eggs on wild lupine. These eggs develop into the adults of the second Karner blue butterfly flight, which generally occurs in July and August. Although always near a wild lupine plant, second brood females lay more eggs on grasses, other plants, and litter than 1st brood females. The 2nd flight is typically two to four times the size of the first flight. However, the first flight of Karner blue butterflies can be larger than the second. Timing and size of both flights can exhibit substantial variation, depending on local weather conditions among other factors.
A wide range of values related to Karner blue butterfly recruitment have been reported. Adult Karner blue sex ratios vary from 1 male to 1.44 females to 2 males to 1 female. Wild caught Karner blue butterfly females have been observed to lay from 7.7 to 83 eggs on average. Reported percentages of eggs that reach adulthood under controlled conditions vary from 21.4% to 75.2%. In the wild, loss of eggs may be substantial.
Karner blue butterflies do not typically move vary far, with males usually moving further than females, with most studies showing average distances moved by individual butterflies of well under 1000 feet.
Adult Karner blue butterflies obtain nectar from several native and nonnative species. Karner blue butterflies have been reported feeding on the nectar of 41 different species in a single study in west-central Wisconsin. Broods differ significantly in the species used for nectaring, likely due to differences in their phenology. Several blackberries have been documented as food sources for the spring brood, while spotted beebalm, white sweetclover (Melilotus alba), and flowering spurge (Euphorbia corollata) are widely cited sources of nectar in the summer. Common cinquefoil (Potentilla simplex) is used as a nectar species for both broods. Karner blue butterflies' preferred nectar species may include butterfly weed in New York and Michigan and lyrate rockcress (Arabis lyrata), lanceleaf tickseed (Coreopsis lanceolata), white sweetclover, and northern dewberry at Indiana Dunes National Lakeshore. Differences in nectar species used between male and female Karner blue butterflies and across locations have been reported. Other often mentioned nectar sources include New Jersey tea (Ceanothus americanus), wild lupine, goldenrods (Solidago spp.), and spotted knapweed (Centaurea maculosa).
Other likely predators include white-tailed deer and birds. Incidental predation of Karner blue butterfly eggs, larvae, and pupae by white-tailed deer grazing on wild lupine can be substantial.
Wasps are the most commonly reported parasitoids of Karner blue butterflies. A tachinid fly, Aplomya theclarum, has also been listed as a Karner blue butterfly parasite. Two wasps, one from the Trichogrammatidae family and another tentatively identified as a member of the Eulophidae family, are suspected to parasitize Karner blue butterfly eggs.
According to reviews, habitat loss through direct conversion to other land uses and through succession are considered the major causes of the decline of the Karner blue butterfly [22,72]. At the time of this writing (2006), 2 reviews [3,72] summarize the recent status of Karner blue butterfly across its range. Recovery criteria are addressed by [22,72], while Christenson and Lentz  discuss lessons learned developing a statewide Habitat Conservation Plan for Wisconsin.
Articles that address Karner blue butterfly sampling methodology include [5,27,31,53]. Swengel  found that surveys for Karner blue butterfly adults appeared more efficient than those for larvae. Evidence of different catchability and/or detectability of male and female Karner blue butterflies led King  to suggest calculating male and female population sizes separately. General descriptions of Karner blue butterfly rearing methods [25,73] and translocation/ reintroduction techniques [54,70] are available.
A wide variety of management techniques can be compatible with maintaining Karner blue butterfly populations when attention is paid to implementing them at appropriate times and at intensities, scales, and frequencies that Karner blue butterflies can tolerate. For example, mowing can maintain open areas with little to no detrimental effect on Karner blue butterflies on sites where burning is impractical or in areas too small to support populations of Karner blue butterflies likely to survive a burn [54,63,64]. On restored oak savanna sites in south-central Wisconsin, no significant (p=0.924) differences were detected between Karner blue butterfly densities on sites burned in summer, sites mowed in August, and control sites . Mowing with a blade height >4 inches (10 cm) should be performed annually or biennially in the fall or winter and clippings should be left in place [54,72]. Effects of mowing, burning, and other management techniques and land uses on the average number of Karner blue butterflies observed per survey hour are included in . Recommendations on the use of a wide range of management techniques such as thinning, rotational grazing, and planting of wild lupine and/or nectar species can be found in [43,72].
According to reviews and general field observations, management activities that are typically harmful to Karner blue butterflies include management that increases deer and/or grouse populations, close-cropped grazing, frequent or poorly-timed mowing, plowing, use of herbicides that kill lupine or nectar plants, and use of pesticides that are detrimental to Karner blue butterflies, ants they associate with, or pollinators of species they use for nectar [22,51,61,72]. Information on the impacts of an insecticide on Karner blue butterflies  and some herbicides  on Karner blue butterflies as well as lupine and nectar species are available. According to the Karner blue butterfly recovery plan, management activities that can have a detrimental effect should be timed to allow at least 2 generations between repeat treatments and, if possible, critical subpopulations should be divided into discrete management units .