U. S. Fish and Wildlife Service, Digital Library System
Paul Labus, The Nature Conservancy
The following lists are based on the habitat characteristics and plant species
composition of vegetation communities Karner blue butterflies are known to occupy.
There is not conclusive evidence that Karner blue butterflies occur in all the
habitat types listed, and some community types may have been omitted.
FRES10 White-red-jack pine
STATES/PROVINCES: (key to state/province abbreviations)
SPECIES: Lycaeides melissa samuelis
Catherine Herms, Ohio State University
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 (n=20) to 83 eggs (n=50) on average [10,25,73]. Reported percentages of eggs that reach adulthood under controlled conditions vary from 21.4% to 75.2% [25,70,73]. In the wild, loss of eggs may be substantial . Fate of 2nd-brood eggs was experimentally investigated by Spoor and others .
Karner blue butterflies do not typically move vary far, with males usually moving further than females [2,31,36,40]. More than 75% of maximum distances moved by Karner blue butterflies at Indiana Dunes National Lakeshore were <330 feet (100 m). At 2 sites <2% of Karner blue butterflies had ranges >980 feet (300 m) and at another flatter, more open site 4.3% of adults had ranges >980 feet (300 m) . In a right-of-way in western Wisconsin, 91% of 2nd flight males had ranges <1,310 feet (400 m) and 91% of 2nd flight females had ranges <660 feet (200 m) . In southeastern Minnesota, average total distance moved was 670 feet (205 m) for males and 190 feet (58 m) for females . At the Allegan State Game Area in Michigan, the mean distances between recaptures of Karner blue butterflies were 810 feet (248 m) for males and 670 feet (203 m) for females . The average maximum distance between butterfly locations (range length) in a restored oak barrens in south-central Wisconsin was 1,500 feet (457.0 m) for 1st brood males and 240 feet (73.3 m) for 1st brood females. However, females of the 2nd brood at this site dispersed further than 2nd-brood males. The average range length was 1,230 feet (373.6 m) for 2nd-brood males and 2,010 feet (613.7 m) for 2nd-brood females .
Movements of ≥ 0.6 mile (≥1 km), including those between sites, have been observed [2,26]. In open habitat in south-central Wisconsin, 7.4% of 1st-flight recaptures and 11.2% of 2nd- flight recaptures moved between sites that were 0.7 to 1.4 miles (1.15-2.25 km) apart . In western Wisconsin, less than 6% (21 of 361) of recaptured, 2nd-flight butterflies were observed to move between study areas from 165 feet (50 m) to 0.6 mile (1 km) apart. The 2 sites that were only 165 feet (50 m) apart were separated by dense vegetation with 75% paper birch (Betula papyrifera) overstory . At the Allegan State Game Area, no between-site dispersal was observed on sites that ranged from 0.3 to 1.5 miles (0.5-2.5 km) apart. Descriptions of the area between Karner blue butterfly sites were not included . A thorough review of Karner blue butterfly dispersal notes the limitations of these studies, including a lack of quantifying search efforts across distances .
Karner blue butterfly larvae benefit from a facultative, mutualistic relationship with several ant
species. In pitch pine-bear oak (Pinus rigida-Quercus ilicifolia) habitat in New York,
significantly (p=0.006) more larvae tended by ants survived (67%) than untended larvae (38%). The 19
ant species tending Karner blue butterfly larvae were from the subfamilies Formicinae, Myrmicinae,
and Dolichoderinae, which are the most common in the area. The species of ant is likely to influence
the degree of benefit gained by Karner blue butterfly larvae . In central Wisconsin, significantly
(p<0.001) more ants tended larger Karner blue butterfly larvae than smaller larvae . At sites
in Wisconsin and Minnesota, ant tending rates increased significantly (p<0.0001) with increasing
larval age. Larvae present long enough to reach pupation were significantly (p=0.01) more likely to
have been tended by ants than not . In a study of the effect of different experimental feeding
treatments, Karner blue butterfly larvae tended by ants had one of the shortest observed larval
durations and gained the most weight for the amount of lupine eaten .
Karner blue butterflies occur in sandy, open areas including oak savannas, pine barrens, and regularly disturbed habitats, such as power line rights-of-way [22,38,43,50,57,72]
Wild lupine: Several studies have found a positive relationship between measures of wild lupine and Karner blue butterfly abundance [2,18,19,37,40,41,51]. At Fort McCoy in south-central Wisconsin, there was a significant (p<0.05) positive relationship between cover of lupine and both the abundance of Karner blue butterflies and the frequency of individual Karner blue butterflies remaining in an area between recaptures. In addition, wild lupine patches with Karner blue butterflies were significantly (p=0.0000) larger (16.3 acres, 6.61 ha) than lupine patches where Karner blue butterflies were not detected (3.6 acres, 1.47 ha) . A more recent study in the same area obtained similar results, with occupied patches (x=10,570 m²) significantly (p<0.001) larger than unoccupied wild lupine patches (x=2,939 m²) . Although results were preliminary, the number of Karner blue butterflies observed was significantly (p<0.001) correlated (r=0.547) with the number of wild lupine rosettes on sites in New York . At Indiana Dunes National Lakeshore, plants with Karner blue butterfly larval feeding damage had higher local density (p<0.05) than undamaged plants . A trend for increasing Karner blue butterfly observations on sites with more wild lupine was observed at Fort McCoy. Thirty of 48 patches comprised of 10 to 99 wild lupines were not occupied by Karner blue butterflies, while more than 100 Karner blue butterflies were observed at all 5 patches of more than 100,000 wild lupines . At the Allegan State Game Area in Michigan, lupine abundance was not significantly (p>0.05) associated with Karner blue butterfly abundance, although there was a general trend of Karner blue butterflies being observed on sites with high wild lupine densities . In southeastern Minnesota, a significant (p<0.05) relationship between abundance of Karner blue butterflies and wild lupine was not observed and the site with the highest density of wild lupine had no Karner blue butterflies . The Karner blue butterfly recovery team  recommends a minimum of 500 wild lupine stems for small habitat patches (0.25 ha) and densities of at least 0.1 lupine stems/m² in larger areas.
Available evidence suggests that senescent wild lupine is a poor larval food source [20,37,43]. In a feeding trial, Karner blue butterfly fed senescent lupine had the lowest survival rate and one of the longest larval durations observed . In 1995, plots in west-central Wisconsin with delayed onset of wild lupine senescence had significantly (p<0.01) more Karner blue butterfly larvae . The majority (77%) of the 2nd-flight oviposition sites on wild lupine in Wisconsin and Minnesota were on plants that had not begun to senesce .
The effects of other phenological stages are more ambiguous. In west-central Wisconsin, Karner blue butterfly abundance was negatively associated (p<0.05) with the abundance of reproductive lupine and positively related (p<0.05) with the frequency of immature wild lupine . However, a feeding trial found that Karner blue butterfly fed 1st year wild lupine had one of the lowest survival rates observed and significantly (p<0.05) longer larval durations than larvae fed older wild lupine that did not flower, was flowering, had recently flowered, or was grown in shade and was in seed [20,37]. In addition, on sites in Wisconsin and Minnesota, the number of 1st flight oviposition sites on nonreproductive and reproductive wild lupine was similar .
Many other factors may influence the quality of wild lupine as a Karner blue butterfly food resource. At Indiana Dunes National Lakeshore, wild lupine with Karner blue butterfly feeding damage had significantly (p<0.05) larger leaves and longer and thicker stems than plants without feeding damage . In addition, larval length was positively associated (p<0.01) with wild lupine height in central Wisconsin . Higher nitrogen concentrations in wild lupine leaves resulted in significantly (p=0.01) shorter larval durations in a feeding trial . In 1995 in west-central Wisconsin, significantly (p<0.01) 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 (p>0.05) different from treatments that resulted in the shortest larval durations. Karner blue butterfly fed water-stressed wild lupine had significantly (p<0.05) 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 (see Timing of Major Life History Events), 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 .
Several of the above factors are directly or indirectly influenced by the amount of sunlight wild lupine receives. For more information on the effect of light on wild lupine as a Karner blue butterfly larval resource, see below. For information specific to Wild lupine, see that FEIS review.
Canopy cover: Due to effects of environmental variation and differing requirements among life stages, broods, and sexes, Karner blue butterflies require a mosaic of sun and shade [19,37,43].
Adult Karner blue butterflies' preference for open, sunny areas has been well documented [2,19,43,57,64]. For example, at Indiana Dunes National Lakeshore nectaring sites of both sexes were found significantly (p<0.001) more often in openings than expected based on availability . In a right-of-way in west-central Wisconsin, patches occupied by Karner blue butterflies in 1992 had significantly (p=0.0136) less overstory cover than unoccupied patches . In the Allegan State Game Area in Michigan, there was a negative relationship between tree density and the occupancy of wild lupine patches by Karner blue butterflies . In addition, Karner blue butterfly abundance was significantly (p=0.000) negatively associated with canopy cover in pine-oak barrens of Wisconsin . However, canopy cover was not a significant predictor of Karner blue butterfly abundance in a generally shady portion of the Allegan State Game Area, and patterns suggested the greatest abundance in areas of interspersed sun and shade . In addition, the proportion of adults of both broods in shaded plots in a hot, dry year was more than twice the levels observed in a previous, cooler year on sites in oak and pine barren habitat of west-central Wisconsin . 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 [19,37,43].
Adult Karner blue butterfly females are more likely to use shaded habitats than males [19,31,43]. At Indiana Dunes National Lakeshore males were captured at sites with significantly (p<0.001) less canopy cover (19.7%) than females (26.0%) . In another study at Indiana Dune National Lakeshore, almost 90% of male activities were observed in open areas, while female activities were more evenly split between shaded and open habitats. Second brood males and females differed significantly (p<0.001) in their use of various canopy cover categories. Females used shaded areas significantly (p<0.05) more than males, and males used open areas significantly (p<0.05) more than females. Females also oviposited most often in sites with 30%-60% canopy cover, despite lupine being more abundant in open areas . In oak savanna habitats in Wisconsin and Minnesota, females laid the fewest eggs in areas with ≥76% canopy cover . Avoiding harassment by males [37,43] 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 [19,37,43]. In west-central Wisconsin, abundance of spring adults positively correlated (r²=0.35) with decreasing canopy cover, while correlation with summer adults was very weak(r²=0.03) . At Indiana Dunes National Lakeshore, cover at late summer oviposition sites was significantly (p<0.001) higher (60.3%) than at late spring oviposition sites (34.7%) . In Wisconsin and Minnesota, late spring oviposition sites occurred in partial (16-75% cover) and closed (≥76% cover) habitats significantly (p≤0.012) 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 (p≥0.217) 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 [20,38,43]. In oak savanna sites in Wisconsin and Minnesota, significantly (p=0.0052) greater larval survival rates were observed in closed subhabitat (≥76% canopy cover) . In 1994 in oak and pine barren habitat of west-central Wisconsin, summer larvae where found in plots with ≥80% cover significantly (p=0.0067) more often than open and partially shaded plots. In 1995, which was a hot, dry year this trend was more evident (p=0.001); 66% of larvae were observed in the most shaded plots, which was 2 to 4 times that of other canopy cover categories . 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 suggested by Maxwell . This agrees with findings of a feeding trial which found a significant (p=0.01) correlation (r= -0.76) between leaf-nitrogen content and larval duration as well as significantly (p<0.05) shorter larval durations in Karner blue butterfly fed shade-grown lupine in seed compared to those fed similar sun-grown lupine. Larvae fed water-stressed wild lupine also had longer larval durations . The size of wild lupine has been positively associated with Karner blue butterfly larval length  and amount of feeding damage. At Indiana Dunes National Lakeshore leaves of wild lupine growing on the shadier northern sides of dunes were significantly (p=0.01) larger than those growing on the sun-exposed south aspect . 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 . The Wild lupine subsection of this report reviews literature on Karner blue butterfly response to wild lupine variables, and Successional Status in the FEIS report of wild lupine provides information on the relationship between light and wild lupine.
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. Open habitats had insignificantly (p=0.116) more parasitoids on average than partial (16%-75% cover) and closed habitats .
Nectar species: Nectar availability is likely to influence Karner blue butterfly abundance. In a right-of-way in west-central Wisconsin, the frequency that Karner blue butterflies stayed in an area between recaptures was significantly (p<0.05) positively related to percent cover of nectar flowers such as Canadian horseweed (Conyza canadensis var. canadensis) and spotted beebalm (Monarda punctata) . Preliminary results from a study in southeastern Minnesota suggest that openings where Karner blue butterflies were detected tended to have more flowering nectar species . In Michigan, more Karner blue butterflies were observed on sites with more nectaring plants, especially butterfly milkweed (Asclepias tuberosa) . As discussed in Canopy cover, nectar species increase in open habitats [37,41,43]. For instance, at Fort McCoy in west-central Wisconsin, all the nectar species listed for Karner blue butterflies require either full or partial sun . In addition, treatments such as cutting with or without herbicides, herbicide application alone, or mowing at varying intervals resulted in a significant (p<0.01) increase in the number and cover of nectar species . See Food Habits for species that Karner blue butterflies use as nectar sources.
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 .
Disturbance: Karner blue butterflies may be associated with disturbance. Although results may have been biased by a significant (p=0.009) positive correlation (r=0.2173) between patch area and number of disturbances (such as burning, vehicle traffic, and thinning and clearing), patches in a right-of-way in west-central Wisconsin occupied by Karner blue butterflies had a greater frequency of disturbance than unoccupied patches (p≤0.0125) . In the same area, the abundance of the Karner blue butterfly spring brood was positively related to trails , and the percent of lupine stems with larval feeding damage was significantly (p<0.05) greater in areas disturbed by military vehicle traffic .
Temperature: Karner blue butterflies are directly affected by temperature [37,64]. A laboratory investigation of temperature on Karner blue butterfly found that flight typically begins at 76 °F (24.6 °C) for females and 80 °F (26.4 °C) for males (p=0.25). Signs of heat stress started at 96 °F (35.6 °C) for females and 98 °F (36.8 °C) for males (p=0.25) . In pine-oak barrens in Wisconsin, observation rates of Karner blue butterflies increased significantly (p=0.000) with increasing temperature .
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 .
Landscape effects: Karner blue butterflies are dependant on heterogeneous habitat as it provides the varied requirements of different Karner blue butterfly broods, sexes, and life stages over a wide range of environmental conditions [19,38,43,72]. Research at Indiana Dunes National Lakeshore led to recommendations for canopy openings for adult males and nectaring of both sexes, as well as areas with 30-60% cover for ovipositing females . In the Allegan State Game Area, wild lupine patches occupied by Karner blue butterflies had higher density of edge habitats that unoccupied wild lupine patches . In west-central Wisconsin the importance of shaded habitat led to a recommendation that 20% to 40% of Karner blue butterfly habitat provide shaded lupine and that 1/3 have >60% canopy cover with succession in these dense areas allowed to progress to complete closure. Maxwell  also suggests avoiding any management that would result in habitat homogenization. The Karner blue butterfly recovery team  mentions the importance of a wide range of aspects, hydrology, microtopography as well canopy cover (0-90%) in conserving the Karner blue butterfly. However, Karner blue populations can persist in relatively homogenous habitats. For instance, a population has persisted at the Saratoga Airport in New York in open habitat maintained by regular mowing. More information on the habitat characteristics, environmental conditions, and/or geographic variability in habitat requirements that facilitate Karner blue butterfly's persistence in these areas is needed [19,22,54].
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 .
Dispersal: Given their typically short dispersal distance, the spatial arrangement of habitat is important to the conservation of the Karner blue butterfly. Distance between the various types of habitat required by Karner blue butterflies is likely an influential landscape attribute [37,43]. Lane  suggests that suitable Karner blue butterfly habitat occurs in areas where open and closed canopies occur within a 590-foot (180 m) diameter. Maxwell  recommends considering the amount of shaded wild lupine habitat within the dispersal distance of Karner blue butterfly when reducing overstory. Many investigators stress the importance of habitat patches being closely spaced [2,31,51]. For instance, at sites in west-central Wisconsin, the average distance from an occupied wild lupine patch to another occupied patch was significantly (p=0.002) shorter (709 feet, 216 m) than to an unoccupied patch (1,155 feet, 352 m) . Wild lupine patches in the same area that were occupied by Karner blue butterflies were also surrounded by a relatively low percentage of unoccupied patches . In addition, wild lupine patches in the Allegan State Game Area that were occupied by Karner blue butterflies were closer to other occupied patches than wild lupine patches without Karner blue butterflies. This led to the recommendation that habitat patches be within 230 feet (70 m) of each other . Isolation of habitat patches has been suggested as a reason for lack of Karner blue butterfly presence on sites in New York . In addition, studies of Karner blue butterfly dispersal have led to recommended distance between patches of ≤980 feet (300 m) to allow for dispersal  and management units no wider than 1,300 to 1,600 feet (400-500 m) to improve recolonization of treated areas .
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].
Reviews of Karner blue butterfly life history list wild lupine its sole larval food source [16,22,31,35]. For information on how habitat characteristics affect wild lupine's quality as a Karner blue butterfly resource see Canopy cover and Wild lupine.
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 (p<0.001) 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 [13,21,40,41,61], while spotted beebalm [2,36,40,41],
white sweetclover (Melilotus alba) [2,21,41,61], and flowering spurge
(Euphorbia corollata) [2,40,41,61] are widely cited sources of nectar in the
summer. Common cinquefoil (Potentilla simplex) is used as a nectar species
for both broods [13,21,61]. 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. The
preference for northern dewberry was not related to its abundance. In contrast,
flowering spurge was not usually selected (p<0.001) when there was another nectar
source nearby, and its use increased with its availability. Differences in nectar
species used between male and female Karner blue butterflies (p<0.001)  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) [13,21,22,70]. For a comprehensive
review of Karner blue butterfly nectar species see .
Spiders and many insects are the major predators of Karner blue butterflies. The seven-spotted lady beetle (Coccinella septempunctata) is one of the few confirmed predators of Karner blue butterfly larvae [37,52]. Paper wasps (Polistes spp.), spined solider bugs (Podisus maculiventris), and ants (Formica spp.) have been observed removing larvae , and the ant Monomorium emarginatum was seen chewing on Karner blue butterfly eggs . There is currently no explanation for the removal of larvae or chewing of eggs by some of the same ant species that tend larvae [50,59]. Other potential predators of Karner blue butterfly larvae include green lacewings (Chrysopidae), solider beetles (Cantharidae), and damsel bugs . Predators of adult Karner blue butterflies include dragonflies (Anisoptera) , robber flies (Asilidae) , ambush bugs (Phymatidae) and spiders (Araneae) , such as crab spiders (Thomisidae). Assassin bugs (Reduviidae) are also likely predators of adult Karner blue butterflies .
Other likely predators include white-tailed deer (Odocoileus virginianus) and birds (Aves) . Incidental predation of Karner blue butterfly eggs, larvae, and pupae by white-tailed deer grazing on wild lupine can be substantial [41,54].
Wasps are the most commonly reported parasitoids of Karner blue butterflies.
Likely parasitoids in Minnesota and Wisconsin include wasps in the families
Ichneumonidae, Braconidae, Scelionidae, Elasmidae, and Eulophidae .
A wasp from the family Braconidae and 2 species from the Ichneumonidae,
Neotypus nobilitator and Parania geniculata, were reported as
larval parasites in a review. A tachinid fly, Aplomya theclarum, was also
listed as a Karner blue butterfly parasite . Based on the literature, 2 wasps,
one from the Trichogrammatidae family and another tentatively identified as a member of the
Eulophidae family, were 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 .
Nectar: Given the wide range of nectar species used by Karner blue butterfly (see Food Habits), planting several often used or preferred nectar species is favored over selecting 1 or 2 specific species. Species selection should attempt to provide nectar sources in both open and partially shaded conditions throughout the growing season despite yearly variation in environmental conditions [21,72]. Planting nonnative nectar sources is discouraged due to their potential impacts on native food sources, especially wild lupine .
Heterogeneity: Heterogeneity is an important feature of Karner blue butterfly habitat. Specific recommendations regarding the spatial arrangement of the various required habitat types and Karner blue butterfly habitat patches are discussed in Landscape effects. Creation and rotation of management units should incorporate this information as well as data on Karner blue butterfly movement (see Timing of Major Life History Events) . Bidwell  recommends management units be a maximum of 1,300 to 1,600 feet (400-500 m) wide to improve recolonization from neighboring areas. Depending on the available and surrounding habitat, managing for heterogeneity could mean implementing a wide range of techniques [43,72].
SPECIES: Lycaeides melissa samuelis
There are several reports of fire having dramatic negative effects on Karner blue butterflies. Schweitzer  asserts that 100% mortality of Karner blue butterflies on burned sites should be assumed for fire management planning purposes. Knutson and others  report observing high Karner blue butterfly mortality due to fire. In a burned area at Indiana Dunes National Lakeshore relative abundance of the 1st flight of Karner blue butterflies was reduced by 33% . The lack of Karner blue butterfly larvae or larval feeding sign in areas burned during fall and spring suggests a high degree of fire-related egg and larval morality [4,17,43,63]. On sites in Wisconsin, no spring-brood larvae were observed and there was little to no feeding damage on units burned during spring or fall. Preliminary data suggested that the abundance of 1st-flight Karner blue butterflies was also lower in burned units compared to unburned units . No 1st-brood larvae were observed on 30 m² x 50 m² plots burned in spring or fall, and larval feeding damage was significantly (p<0.01) higher in control plots in west-central Wisconsin. Adults of this brood were also less common on burned plots . In central Wisconsin no larvae were observed on recently-burned areas, despite the presence of adults on the site the previous summer and larvae in nearby unburned areas . At Indiana Dunes National Lakeshore, 1st-brood feeding damage in areas burned the previous fall was substantially less than in unburned areas .
Despite apparently high fire-related Karner blue butterfly mortality, several studies have found fire to have little impact on Karner blue populations. Although the proportion of Karner blue butterflies observed in burned areas at Indiana Dunes National Lakeshore declined following small (<88 acres) fall and spring burns that included refuge areas, no overall population declines were detected . Anecdotal reports from the Allegan State Game Area in Michigan suggest that Karner blue butterflies survived a burn on an open field site and that the burn did not impact the population . Similarly a low-severity surface fire that burned a substantial proportion of a site in the Albany Pine Bush did not have a noticeable effect on the Karner blue population on the site . In pine-oak barrens of Wisconsin, Karner blue butterflies occurred in "favorable numbers" in areas managed with fire . In a mark recapture study in south-central Wisconsin on restored oak savanna sites with an average fire rotation of 3.5 years, no Karner blue butterfly mortality was observed during July burns and recapture rates of adults marked before the fires (2.9% and 6.7%) were similar to recapture rates on an unburned site (4.3%) . The only study of Karner blue butterfly response to fire that incorporated both controls and replicates was performed on the same study site. Although limited by small sample size, there was no significant difference between the density of Karner blue butterflies on control sites and on 1.2- to 47.4-acre (0.5-19.2 ha) sites burned in July (p=0.230) or November (p=0.337). The following table shows the average density of Karner blue butterflies per hectare (±sx) within the different treatments and over the course of the experiment .
|Year||Summer burn vs. control||Fall burn vs. control|
|Pretreatment years||1993||31.0 ± 17.6||35.1 ± 20.9||32.0 ± 21.4||21.8 ± 5.0|
|1994||44.3 ± 21.9||50.6 ± 25.4||21.8 ± 11.0||13.7 ± 3.7|
|Posttreatment years||1995||65.0 ± 19.3||40.3 ± 24.5||93.8 ± 85.9||39.5 ± 36.5|
|1996||186.4 ± 74.7||101.0 ± 47.0||478.1 ± 471.9||179.2 ± 169.1|
|1997||72.7 ± 40.8||83.9 ± 51.5||152.5 ± 142.9||76.8 ± 72.8|
There are likely several reasons for the varying Karner blue butterfly responses. Although different investigative methods and study areas are likely to explain some of the variation, most trends relate to season and fire characteristics.
It appears that burning while Karner blue butterfly eggs are overwintering or 1st-brood larvae are developing may have a larger impact than summer burning. Many of the studies reporting a negative response of Karner blue butterflies investigated the response of larvae to fire during the overwintering (fall-winter) or early larval period (spring) [4,17,43,63]. Studies investigating the response of 2nd-flight Karner blue butterflies to summer burns found no evidence for a detrimental effect of burning [28,29]. Given that eggs and larvae are typically located on lupine or nearby vegetation (see Timing of Life History Events), fires during these stages of their life history are likely to cause greater mortality than during the more mobile adult stage . Some Karner blue butterfly eggs fall from the oviposition site into the litter or soil [54,59]. Whether or not this provides some protection against fire is unknown.
Size and uniformity of the fire are also likely to influence Karner blue butterflies' response. A study at Indiana Dunes National Lakeshore that found no overall population declines due to a fire had small (<88 acres) burn units that included refuge areas ranging from 164 to 984 feet² (50-300 m²) . No burn units were greater than 47.4 acres (19.2 ha) in the study in south-central Wisconsin on restored oak savanna sites that found no differences in Karner blue butterfly density on fall and spring burn sites compared to control , and prescribed burns used in the mark recapture study in the same area were ≤ 27.4 acres (11.1 ha) . Large, uniform burns are likely to have a greater negative impact on Karner blue populations. Not only will a larger proportion of a population be directly affected by the fire, but greater distances to unburned habitat mean recolonization of the burned area may be slow (see Dispersal) [35,43,54,64,72].
Fire severity is another factor that may influence Karner blue butterflies response to fire. Zaremba and Gebauer  suggest that the lack of a discernible response of a Karner blue butterfly population to a surface fire in the Albany Pine Bush may have been due to its low severity. In addition, King  speculates that the lack of a response of Karner blue butterfly density in restored oak savanna of south-central Wisconsin may have been due to the low severity of the fires.
Lastly it has been suggested that decreasing the frequency of burning to allow Karner
blue butterfly populations time to recover and recolonize burned units would decrease
the risk of population declines [54,72].
HABITAT-RELATED FIRE EFFECTS:
Karner blue butterflies use and in some cases may prefer burned habitat. Although several other factors could be involved, Karner blue butterfly numbers were greater 2 years after a wildfire killed many mature oak trees on a site at the Allegan State Game Area . On sites at Indiana Dunes National Lakeshore burned in fall, increases in larval feeding damage from the 1st to the 2nd brood demonstrate oviposition by 1st-brood adults in burned areas . Casual observations in Wisconsin suggest that adults may prefer more recently burned over less recently burned areas . In west-central Wisconsin, lupine patches occupied by Karner blue butterflies had significantly (p=0.0097) higher mean frequency of burning (0.44) than unoccupied lupine patches (0.13). However, the finding may have been biased by a significant (p=0.009) positive correlation (r=0.2173) between patch area and number of disturbances . Despite declines in the spring brood of Karner blue butterflies following burning, significantly (p<0.01) more 1st-flight butterflies were observed on burned plots in areas of west-central Wisconsin in the following year. In the summer after the fall and spring burns, summer brood larvae were significantly (p=0.035) more dense in burned plots. In addition, portions of plots directly-seeded with various grasses and nectar plants and burned in late April had significantly (p≤0.001) higher densities of summer brood larvae than unburned portions. These results indicate a preference of females to oviposit in burned areas and/or an increased survival rate of immature Karner blue butterflies on these sites .
Weather conditions after fire can influence Karner blue butterfly response. For instance, Swengel  suggests that Karner blue butterflies may have a more positive response to a spring burn if it is followed by a moist, rather than a dry, summer. In west-central Wisconsin, during a hot, dry summer there was a significant (p<0.05) decline in larval density on burned plots with reduced overstory cover, while larval densities on control plots showed an insignificant (p=0.47) increase . Fire management plans should be adaptable to changes in Karner blue butterfly populations resulting from unusual weather conditions (see Temperature) or other uncontrollable events .
The effectiveness of fire at maintaining open Karner blue butterfly habitat depends on several factors including season, frequency, and severity of burning. A wildfire at the Allegan State Game Area killed many mature oak trees on a site. However, in the same area herbaceous vegetation 2 months after a prescribed burn did not differ substantially from unburned areas . At the Necedah Wildlife Management Area in Wisconsin, single fires performed in May or October in degraded oak savanna did not have substantial impacts on habitat structure . Histories of sites occupied by Karner blue butterflies in Wisconsin suggest summer wildfire can kill woody growth and create Karner blue butterfly habitat, while spring and fall burning can maintain open Karner blue butterfly habitat . Bleser  summarizes information from the literature that suggests that fall and summer burns cannot reduce the encroachment of woody brush, even when used frequently, while summer burns can be more effective in reducing woody vegetation. However, a review suggests that burning in August is difficult due to moist, green, conditions  and burning in restored oak savanna in July resulted in low-severity fires . In oak and pine barren habitat of west-central Wisconsin, spring burning produced more severe fires than fall burning, due to higher fuel loads. The effects of this increased severity were most noticeable in closed canopy plots . Grundel and others  suggest that several fires over 10 to 20 years may be necessary to return forests at Indiana Dunes National Lakeshore to savanna. In oak savanna of east-central Minnesota the rate of decline in tree density from 1984 to 1995 was significantly (p=0.006) correlated (r²=0.55) with fire frequency. For more information on the effect of fire frequency in oak savanna of this area see [48,67,68]. The frequency of fire necessary to create or maintain open Karner blue habitat is uncertain but may be greater in savannas than pine barrens  and greater on wet sites than dry areas . Typical burning intervals in areas occupied by Karner blue butterflies are 3 to 5 years or greater [29,54,64,72].
Although open areas are an important component of Karner blue butterfly habitat, burning heterogeneity should be incorporated into fire management plans so that the mosaic of open and shaded areas required by Karner blue butterflies is created or maintained  and to allow for faster recolonization of burned areas. Due to the likelihood of high fire-related Karner blue butterfly mortality, the ability of Karner blue butterflies to recolonize burned areas is considered a major factor influencing their postfire recovery. Burning portions of the occupied Karner blue butterfly habitat, incorporating unburned areas within a burn unit, and implementing at a scale appropriate for Karner blue butterfly dispersal are likely to result in faster recolonization of burned areas than otherwise possible [4,31,35,54,61,62,72]. For example, 1st-flight adult Karner blue butterflies were observed recolonizing small (approx 0.4 acres, 0.16 ha) units near unburned sites in Wisconsin that were burned earlier that spring . Small (98 x 164 feet, 30 x 50 m) experimentally burned plots in west-central Wisconsin were also quickly recolonized by adult Karner blue butterflies . Splitting occupied Karner blue butterfly habitat into several management units and burning so consecutive burns do not occur in adjacent units has been used to maximize recolonization potential [35,54]. Schweitzer recommends at least 3 and preferably 5 or more management units per local Karner blue population and not burning adjacent units within 3 years of each other . In addition to dividing populations into separate units, recolonization can be facilitated by incorporating unburned, refuge areas within burned units [17,35,54]. At Indiana Dunes National Lakeshore, burned units contained 1 or more unburned areas ranging from 164 to 984 feet² (50-300 m²) . Shuey  provides a review of Karner blue butterfly that focuses on the effects of disturbance at the landscape level, while Lyon and others  provide a more general review of fire and landscape scale considerations.
Karner blue butterfly's response is likely influenced by the effect fire has on lupine and nectar species. Before burning in west-central Wisconsin there was a negative relationship between Karner blue butterfly larval abundance and reproductive lupine. Within 2 years of burning this changed to a positive relationship, which may indicate that burning resulted in an improvement in reproductive lupine as a Karner blue butterfly resource . See the Fire Effects section of the FEIS review on wild lupine for information specific to wild lupine and fire. Although in many cases the response of individual nectar species will not have a substantial effect on Karner blue butterfly , the overall impact of fire on nectar species could influence Karner blue butterflies' response to fire. The effect of fire on nectar species varies. In restored oak barrens of Wisconsin, all known Karner blue nectar species increased after fire and in the case of goldenrods the increase was significant (p<0.1) . However, in oak and pine barren habitat of west-central Wisconsin, burns in open plots did not increase cover of nectar species and important nectar species, such as spotted beebalm and fewleaf sunflower (Helianthus occidentalis), declined significantly (p<0.01) after fall and spring burns. Of the 16 nectar species studied, lyrate rockcress, northern dewberry, black-eyed Susan (Rudbeckia hirta), and downy phlox (Phlox pilosa) increased after fire across most of the light gradient. In shaded habitats (>80% cover) roundhead lespedeza (Lespedeza capitata) and longbract wild indigo (Baptisia bracteata var. leucophaea) increased significantly (p<0.05) following burning . FEIS includes reviews on a few Karner blue butterfly nectar species including white sweetclover, New Jersey tea, and spotted knapweed.
The response of associated species such as ant attendants and predators to fire may also impact Karner blue butterflies. In savanna and barren habitats of west-central Wisconsin, the rate of ant attendance was significantly (p<0.01) less in burned plots than unburned plots in 1995, a hot, dry year. Burns in plots previously seeded with grasses and Karner blue butterfly nectar species resulted in increases in ant attendance in 1997, possibly due to decreased thatch . Schweitzer suggests that increases in Karner blue butterflies on burned sites could be due to high fire-related mortality of many Karner blue butterfly predators .
Fire regime: The fire intervals of areas where Karner blue butterflies occur are influenced by several factors including habitat, historical period, and weather conditions [9,49,74,75]. Information regarding fire regimes in Karner blue butterfly habitats such as savannas [9,66,74,75] and pitch pine barrens [34,74,76] is available. Most Karner blue butterfly habitats experience fairly frequent fires [9,74,75]. Fires occur at various times of the year in these areas, although a fire history study in oak savanna of southeastern Wisconsin found that mid-growing season fires were uncommon .
The following table provides fire return intervals for plant communities and ecosystems where Karner blue butterfly is likely to occur. For further information, see the FEIS review of the dominant species listed below.
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||<10 [32,47]|
|jack pine||Pinus banksiana||<35 to 200 [8,11]|
|pitch pine||Pinus rigida||6-25 [6,23]|
|aspen-birch||Populus tremuloides-Betula papyrifera||35-200 [11,74]|
|white oak-black oak-northern red oak||Quercus alba-Q. velutina-Q. rubra||<35|
|northern pin oak||Quercus ellipsoidalis||<35|
|bear oak||Quercus ilicifolia||<35|
|bur oak||Quercus macrocarpa||<10 |
|oak savanna||Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium||2-14 [47,74]|
|black oak||Quercus velutina||<35 |
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