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The Permit
A U.S. Fish & Wildlife permit allowed the Conservancy to collect up to 20 mated female Karner blues each year from the Indiana Dunes National Lakeshore. Females could be kept for five days to collect eggs. Afterwards, they were returned to the wild.
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Lupine and puccoon in bloom at Ivanhoe
© Paul Labus | Preparation
Because Karner blue larvae exclusively feed on lupine leaves, female butterflies lay eggs directly onto lupine plants. For the Conservancy’s project, potted plants served as host to the females. They were numbered and covered with nets to prevent accidental escapes. Grow lamps were suspended over the plants.
Collection
The Conservancy tried to collect on warm, dry days when butterflies are most active. It is impossible to determine if a female already has mated, but there are signs to look for:
- Prior to mating, females congregate in sunny openings in the oak savanna.
- After mating they spend most of their time moving among lupine plants searching for appropriate places to lay eggs, occasionally visiting other flowers for nectar.
- Butterflies that are ready to oviposit repeatedly touch the tip of their abdomen to the lupine while moving along the plant.
Once a butterfly was captured, she was placed in a transport container that contains water and nectar sources. Within one hour, they were taken to the office and transferred to the netted lupine plants. Each butterfly was given a number and remained on the same plant for the entire time.
Waiting for the Karner Blues to Lay Eggs
Fresh-cut flowers and small pieces of sponge soaked in a honey-water solution were placed inside the nets. They served as nectar sources for the butterflies. The plants were misted regularly, and nectar sources changed daily. Butterflies were monitored closely.
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Staff member Bonnie Wolf sets up a release net
© Paul Labus | The Hard Part: Harvesting Eggs
After the butterflies were returned, egg harvesting began. Each lupine plant was brought out of the tent and searched for tiny white eggs. Because Karner blue eggs are only about a millimeter across and each butterfly can lay up to 125 eggs, this was a massive, painstaking job.
Eggs were lifted off the plants with a small brush and placed in a Petrie dish with fresh lupine leaves. The butterfly identification number, the number of eggs, usually five or six, and the date were marked on top of the dishes. Each butterfly’s fertility rate and larval success was tracked. Because it is impossible to find every egg, some larvae hatch on the potted plants. For that reason, the plants remained netted within the tent and were searched daily for signs of caterpillars.
Eggs Hatch
The eggs can hatch in a mere five days, so it is important to closely monitor the dishes. Each new larva is recorded with a tic mark on the lid of the dish. Freshly-hatched caterpillars are not much bigger than the eggs, so extreme care was required in caring for them. As they grew, caterpillars were separated into smaller groups. With 1,180 eggs in 2002, which produced 811 larvae, this was no small feat.
Pupation
The next stage in Karner blues' life cycle is pupation, during which caterpillars undergo the metamorphosis into adult butterflies. Pupation usually lasts seven to 10 days and culminates with the emergence of the adult butterfly. The pupae were monitored daily for signs of development.
Releasing the Butterflies
The Conservancy’s goal was to allow the adult butterflies to emerge at the preserve. About 24 hours before then, pupae were transferred to release nets that were located adjacent to their habitat. After the adults emerge, they climb up the sides of the nets, eventually finding their way out and into the open preserve.
The Results
The Conservancy hopes to establish a self-sustaining population within a three-year period. In the first two years, 1,000 butterflies were released at the preserve. Now, the Conservancy is monitoring the initial effort to determine the size of core populations as well as dispersal patterns within the preserve.
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