The Nature Conservancy
Indiana Chapter

Southern Lake Michigan Rim

Background
In the early 1990s Ivanhoe Nature Preserve supported a small population of Karner blue butterflies. At the time the Nature Conservancy was attempting to expand the amount of available habitat for the butterfly within the preserve. Unfortunately, in 1996 wildfires and bad weather decimated the population, and Karner blue disappeared from the preserve the following year. We continued restoring habitat but with re-introduction of Karner blue as the new goal. For a more detailed description of the program, click here: Project Origin.

The Permit
Our re-introduction strategy is to capture mated first brood females from the wild, rear their offspring in captivity through pupation, and allow butterflies to emerge as second brood adults at the preserve. See About the Karner blue for more detail about the life cycle of the Karner. The USF&WS permit allows us to collect up to twenty mated female Karner blues per year from the Indiana Dunes National Lakeshore. The Lakeshore supports two fairly large and stable populations of the butterflies and it is believed that removing twenty females will not have a major impact there. We are allowed to keep the females for five days, during which time we collect eggs. At the end of the five days we return the live butterflies to the wild. If more than five of the butterflies die during the captive period we are required to contact the Fish and Wildlife Service to determine the cause and appropriate actions. The permit, issued in 2001, lasts for three years. In addition to the USF&WS permit our work requires a permit from the National Park Service for collecting on their property.

Preparation
Because Karner blue larvae feed exclusively on lupine leaves, the female butterflies lay eggs directly on to lupine plants. For our project, potted plants serve as host to the females. The plants are started in winter and grown in a greenhouse through the spring. Most of the plants (we grew 10,000 plugs in 2002) are used in habitat restoration, however approximately 40 seedlings are transplanted to pots. Just prior to collecting adult butterflies, the potted plants are transferred to our office where they are numbered and covered with a small net. Our rearing facility consists of a large frame covered with netting to prevent accidental escapes. Inside the frame is a shelf to hold the lupine plants with grow lamps suspended over them.

Collection
The first brood of Karners emerges at the end of May and beginning of June. The adult butterflies live about a week in the wild, which means that the peak flight time last only a few weeks. We try to collect on warm dry days when the butterflies are most active. While it is impossible to determine if a female has already mated there are signs we 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. To avoid over collecting in any one spot we move through several habitat patches capturing every other female.
Once a butterfly is captured she is placed in a transport container that contains both a water and nectar source. Within an hour of capture the butterflies are transported back to our office where they are transferred to the netted lupine plants. Each butterfly is given a number and remains on the same plant for the entire time. Vials with fresh cut flowers are placed inside the nets along with small pieces of sponge soaked in a honey-water solution to serve as nectar sources for the butterflies. The plants are misted regularly and the nectar sources changed daily. The butterflies are monitored closely. Butterflies that do not produce eggs after a few days or exhibit egg laying behavior are assumed to be unmated and are returned to the wild. The collecting process takes place over several days and the target number is adjusted based on how many eggs the captive butterflies are producing.

The Hard Part
After five days each butterfly is returned to its capture site and egg harvesting begins. Each lupine plant is brought out of the tent and searched for the tiny white eggs. Because Karner blue eggs are only about a millimeter across and each butterfly can lay up to 125 eggs, this is a massive and painstaking job that requires either 20/20 vision or magnifying aids. Eggs are gently lifted off the plants with a small brush or the tip of a knife and placed in a Petrie dish along with fresh lupine leaves. The butterfly identification number, the number of eggs, usually five or six, and the date are marked on the top of the dishes, which are then stacked in a larger container.The fertility rate and larval success are tracked for each butterfly. Because it is impossible to find every egg, some larvae hatch on the potted plants. For that reason the plants remain netted within the tent and are searched daily for signs of caterpillars.
The eggs can hatch in as quickly as five days so it is important to monitor the Petrie dishes closely. 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 is required in changing out the lupine leaves. The caterpillars develop over a period of ten to fourteen days. Larger caterpillars are separated into smaller groups until there are only one or two per Petrie dish. As the caterpillars grow they consume more lupine and produce more frass. To avoid any problems with mold they are placed in clean dishes every day with a fresh supply of lupine leaves. Each dish is meticulously cleaned and used again later. With a total of 1,180 eggs in 2002, which produced 811 larvae, this was no small feat.

The next stage in Karner blues' life cycle is pupation, during which the caterpillars undergo the metamorphosis into adult butterflies. Pupation ususally last between seven to ten days culminating with the emergence of the adult butterfly. The pupae are grouped into Petrie dishes according to the date they began pupation and are monitored daily for visual signs of development.

Releasing the butterflies
Our goal is to allow the adult butterflies to emerge at the preserve. Approximately twenty-four hours before eclosion, the pupae are transferred to release nets that are located adjacent to appropriate Karner blue habitat. The release nets are inverted mosquito hats suspended from tree branches by nylon fish line; they are designed as a safe guard against predation. After the adults emerge they climb up the sides of the nets eventually finding there way through the opening at the top. At that point the butterflies are free to move throughout the preserve.

Results
Our hope is to establish a self-sustaining population within the three-year period. We chose a target of releasing 1,000 butterflies at the preserve, which we accomplished in the first two years. Barring problems from wildfires or the weather we do not anticipate rearing additional butterflies in 2003. We will continue monitoring to determine the size of core populations as well as dispersal patterns within the preserve.

back to top

The temporary nursery before the Karner are brought in

Adult emerging from release net