The Karner blue butterfly and the Pink-oak barrens Ecosystem
Maija E. Benjamins
Karner blue butterfly (female top, male bottom)
Karner blue butterfly - What does it look like?
The Karner blue butterfly is a member of the insect order Lepidoptera, meaning "scaly wing" in Latin. This species is in the family Lycaenidae that includes most of the smaller butterflies - the blues, the coppers, and the hairstreaks. The Karner blue feeds solely on blue lupine during the larval stage.
Inner wings of a male Karner blue
(photo courtesy of Dr. Donald J. Leopold)
Outer wings of a male Karner blue
(photo courtesy of Dr. Donald J. Leopold)
All butterflies and moths have four wings - two forewings and two hindwings. The Karner blue butterfly has a wingspan of about one inch. The male's inner wings are a purplish-blue color and lined with a black and white border around the edge. The female's inner forewings are blue in the center and fading into a blackish color with a white border around the edged. The lower hindwings are also blue and lined with a white border, but they have orange spots around the bottom edge of the wing. For both the male and female, the outer wings are a silvery-blue color with orange dots along the border of the both the forewings and hindwings. The thorax and abdomen are a silvery-blue color.
Karner blue larva with tending ant
The larva (or caterpillar) of the Karner blue butterfly is a bright green color with a dark green line running down the back. The coloration of the larva matches the color of the leaves of the blue lupine that they feed
blue lupine
Karner blue egg on a blue lupine stem
The eggs that the females lay are very tiny. If you're not careful, you'll miss the 0.35mm by 0.1mm egg. The Karner blue eggs are flattened with a slight depression in the center and are covered with miniscule bumps. They can be found on the stem of a blue lupine or blue stem grass approximately 3-15 cm from the ground.
The endangered species
The Karner blue butterfly was discovered in 1861 by the famous butterfly expert, Vladimir Nabokov in Karner, New York. This butterfly is a subspecies of the more common Melissa blue butterfly. In the early 1900s, the Karner blue butterfly was described as covering the fields of its habitat "in a sea of blue." In the past decade, the populations of this insect have declined by over 99% with small remnants of the population remaining. Since 1992, the Karner blue butterfly has been listed as a federally protected endangered species under the Endangered Species Act of 1973.
Past and current distribution of the Karner blue
(modified from Anonymous 1992)
The Karner blue was once found along a narrow band ranging from Minnesota and southern Ontario to Maine. The range of this species is limited to the range of blue lupine and climatic variables. With habitat destruction and changing climatic conditions, the Karner blue now only exists in isolated populations in New Hampshire, New York, Michigan, Wisconsin, Indiana, and Minnesota. The remaining populations are very unstable and the brink of localized extinction.
Lifecycle
Life Cycle of the Karner blue butterfly (modified from Dirig 1994)
The Karner blue is bivoltine. Their life cycle begins each year in mid-April as the Karner blue butterfly eggs emerge from diapause. At this time, the blue lupine is beginning to grow. The larvae feed, growing from a 1 mm to 1 cm, until the end of May. The larva then crawls off of the lupine plant and pupates on a nearby plant or in leaf litter.
In the beginning of June, the first male hatches, hangs from the plant to dry out his wings, and begins to fly around and feed. Some Entomologists believe that the male Karner blues will establish small territories before mating. These territories probably attract females with the amount of lupine and egg laying habitat within them. The better areas will attract more females ensuring the particular male in that territory will have a higher frequency of mating.
The females will hatch in the next few days and will begin feeding, mating, and laying eggs immediately. A single Karner blue female can lay up to eighty eggs. The adults live for about two weeks and nectar on a sea of blue lupine, New Jersey tea, wild strawberry, black berry, dewberry, and hawkweed.
Field of blue lupine with hawk weed and pitch pine
The females will lay eggs on the blue lupine in the area. These eggs will then hatch in mid-June repeating the cycle of larva, pupa, and butterflies.
Butterfly weed
The second generation of Karner blue butterflies will fly in mid July and nectar on butterfly weed, horsemint, and spreading dogbain. The females of this generation will lay their eggs in blue stem grass and senescent lupine. These eggs will not hatch until the next April, beginning the entire life cycle again.
Habitat
The forever shrinking and fragmented habitat of the Karner blue butterfly is the oak-pine barrens and savannas. Glaciers that covered the northern half of North America during the Pleistocene glaciation formed most of these barrens.
This glacier striped the area of any vegetation and left a sandy plain of land that extends from Maine to Minnesota and into Ontario (the habitat of the Karner blue butterfly and blue lupine).
Sandy, nutrient poor soils, minimal water availability, and a mosaic of trees and low growing plants characterize the pine-oak barren habitat. This habitat is referred to as high disturbance ecosystem because it is subjected to alteration by seasonal fires (fires lit by lightening in the springtime). The characteristic plant and animals of this ecosystem are adapted to the nutrient poor soils, low water availability, and the seasonal fire regime.
Controlled fire at the Albany Pine Bush
(courtesy of APB)
A few of these characteristic species are:
| pitch pine | scrub oak | fire cherry |
| scarlet oak | blue berry | huckleberry |
| sweet fern | NJ Tea | dew berry |
| spreading dogbain | blue lupine | bastard toadflax |
| butterfly weed | little blue stem grass | panic grass |
Example of a Pine-Oak Barren ecosystem
My Research
As the natural disturbance cycle of the pine-oak barren ecosystem has been degraded due to the influence of people, the habitat has begun to change. The once characteristically mosaic habitat, is now filling in with forests and allowing no sunlight to penetrate its thick canopy. This poses a major problem for the Karner blue because it's main food source, blue lupine, requires full sun to grow.
Dense cover of scrub oak
In an effort to save the Karner blue and the pitch pine-scrub oak barrens, land managers are trying to clear these forests and create full sun habitats for blue lupine to grow. Some Land managers are even trying to re-create a natural fire regime to burn the land. Following the land clearing, nectar plants and blue lupine are often planted. In this effort, however, many species that rely on the tree species are finding themselves homeless. For example, the Pine Barrens buck moth that feeds on scrub oak is rapidly declining in population numbers.
Pine Barrens Buck moth (female right, male left)
(Tuskes et al. 1996)
There has been much speculation over where female Karner blues prefer to lay their eggs. Do they prefer blue lupine plants in full sun or shade? Previous research has demonstrated that the larva actually grow more quickly when feeding on blue lupine leaves that come from plants grown in full shade than partial shade. By growing more quickly, the larva decrease their chances of succumbing to predation and parasitism. The second brood larva will have a better chance of avoiding senescent lupine, as well.
In one component of my research, I want to test if female Karner blues will lay their eggs on full sun or shaded lupine and determine if this shade is equivalent to the shade produced by scrub oak. My hypothesis states: Female Karner blue butterflies will oviposite more frequently on blue lupine in 30% shade then on lupine in full sun or 50% shade.
Methods
In my experimental design, I selected four areas with Karner blue populations. At each area, I located the center of a patch of blue lupine plants and divided the patch into two stratums.
Stratum layout
The first stratum is within a 10 meter radius of the center of the patch and the second stratum is between 10 - 20 meters of the center. Within each stratum, blocks are set up with to no shade, 30% shade, or 50% shade. To the produce the shade, I use shade cloth fastened to four metal stakes, so that it is parallel to the ground. Several of the blocks are equipped with temperature loggers placed in the center of them to monitor the temperature fluctuations throughout the day in order to compare the temperatures of artificial shading and natural effects of scrub oak.
Temperature logger hanging from shade cloth
Once the shade cloth was in place, I waited until the first flight of adult Karner blues had finished in early June, and then we made several measurements on each plot. 
To account for any differences in the size or shape of the blue lupine in each plot, I measured the length, width, height, % cover, number of stems and flowers, and the height of the longest stem for that particular blue lupine plant. For the Karner blue counts, we counted eggs and larva. We measured the length of the stem that the Karner blue was on and we noted where that particular larva was located (for example - stem, leaves, flowers). Since this species is often found with ants, we counted the number of ants found on the plant and noted if the ants where tending a particular larva.
Frosted elfin larva on blue lupine pod
There is another species of butterfly, the frosted elfin, that feeds on blue lupine as a larva. The frosted elfin is in the same family as the Karner blue and has declining populations, as well. This butterfly has a different life cycle from the Karner blue, but we wanted to see if the frosted elfin and the Karner blue larva could be found on the same plant. We counted the frosted elfin larva on each plant, as well.
Adult frosted elfin
Preliminary results
This project needs to be repeated for one more year to have adequate data to be analyzed. Preliminary results seem to support my hypothesis. The 30% shade plots contained more eggs, suggesting that the female Karner blue butterflies preferred the 30% shade plots to the full sun or 50% shade plots. The results based on the different stratums are not as clear.
Management implications
With so many ecosystems disappearing from the world, it has become increasing important to conserve what we have left. As for the Karner blue butterfly, a management strategy has not yet been developed. If my hypothesis is correct and I demonstrate that this species prefers a percentage of shade, land managers will be able to manage their land on an ecosystem level. To conserve the Karner blue butterfly, we need to conserve the complete pine-oak barrens habitat and not just the pieces of it that we see as important. If we are able to succeed with this ecosystem approach management, we will be conserving many other species, including the Pine Barrens buck moth.
Other research at ESF
ESF and Niagara Mohawk Power Company are working together to develop a management strategy for blue lupine on power line right-of-ways. Under the guidance of Dr. Donald J. Leopold, several students are studying the effects of various levels of herbicides and mowing on blue lupine and the surrounding plant communities. By developing a strategy to manage the vegetation on right-of-ways, Niagara Mohawk will be able to conserve the blue lupine and Karner blues on their properties.
Sources used
Anonymous. 1992. Karner blue butterfly Population and Habitat Viability Assessment (PHVA) Workshop Briefing Book. CBSG, The Wilds, Zanesville, OH
Dirig, R. 1994. Karner Bue Butterfly, A Symbol of a Vanishing Landscape. Ed. D.A. Androw, R.J. Baker, C.P. Lane, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, MN
Tuskes, P.M., J.P. Tuttle, & M.M. Collins. The Wild Silk Moths of North America, A Natural History of the Saturniidae of the United States and Canada. Comstock Publishing Associates, Ithaca, NY plate 14
Woodford, A.O. 1965. Historical Geology. W.H. Freeman and Com. San Fransico, CA 440-441.
This research was made possible by the Roosevelt Wildlife Program, http://www.esf.edu/resorg/rooseveltwildlife/default.htm, the American Wildlife Research Foundation, http://community.syracuse.com/cc/awrf, the National Wild Turkey Federations, http://www.nwtf.org/, Quail Unlimited, http://national.qu.org/national/, and Niagara Mohawk, a National Grid Company.
Contact info:
For further information on any of these projects, you can contact:
Maija Benjamins - mebenjam@syr.edu
Donald J. Leopold - dendro@syr.edu
About the author:
I received my B.S. from the Binghamton University in Biology and Theatre. I am currently working on my MS at SUNY-ESF in Ecology. My research interests include the effects of land management on nocturnal lepidopteran communities, the various environmental factors that affect the oviposition behavior of the Karner blue butterfly, how to manage an ecosystem for many declining insect populations, and the effects on land management on various plant communities. As a "scientist," I'm interested in Conservation, Behavioral Ecology, Entomology, and Plant Ecology. After finishing my MS, I'm hoping to head out west to work on my PhD.
Also view the Karner blue and Pine-oak barrens education modules