Do you know about the Zoo’s Grassland Butterfly Conservation Program? Through this program, Endangered prairie butterflies are reared at the Zoo, then released into the wild every summer to increase their population size in Canada and prevent extinction. One of the species the Zoo rears is the Critically Endangered Poweshiek skipperling.
Kirstyn Eckhardt is a master’s student at the University of Manitoba and has been working with our team to study Poweshiek skipperling caterpillars as they develop into butterflies. She explains how one measures growth in such a teeny tiny creature and why this important piece of information can help protect the species.
What are the benefits of studying Poweshiek skipperling caterpillars in human care?
Kirstyn: Poweshiek skipperling caterpillars are challenging to find in the wild, as they blend in with the prairie grasses in their environment. Studying the caterpillars at the Zoo has allowed me to answer questions about how this species develops from egg to butterfly. Poweshiek require an entire year to complete their development, and the caterpillars hibernate under the snow during winter. Like all insects, caterpillars must shed (or “moult”) their exoskeleton to grow. One of the mysteries surrounding Poweshiek skipperling is the number of times the caterpillars moult before they enter winter hibernation. This important piece of information will help researchers better understand how Poweshiek caterpillars develop in the wild.
What methods are you using to measure and document the caterpillars as they grow?
Kirstyn: I am using macro photography to document the caterpillars as they grow. While body length is one way to measure caterpillar size, a more reliable method is to measure the width of the caterpillar’s head. A ruler is included for scale in each photograph, and a computer program is then used to measure the width of the head. Newly hatched caterpillars are tiny, with heads that are fractions of a millimeter wide. Each time the caterpillar moults, its head width increases. The measurements are compared from one day to the next, and an increase in size (usually 30 percent larger) indicates the caterpillar has moulted. Sometimes the caterpillars also leave behind clues, like shed skin, after they moult.
What have you learned about caterpillar development so far? What’s next?
Kirstyn: By monitoring the growth of caterpillars at the Zoo from the time the eggs hatched in July, I determined that Poweshiek caterpillars moulted three times before hibernation began in October. This summer, I will continue to monitor the caterpillars until they are released back into the wild as adult butterflies. It has been incredibly rewarding to follow Poweshiek skipperling through all stages of their year-long life cycle while they are in human care.
What can people do to help critically endangered species?
Kirstyn: You may not have a prairie habitat where you live, but pollinating insects and rare habitats are everywhere. Protect native habitats and support organizations that are working towards that goal. You can also create habitat for species at your home, school, work, and community by choosing native plants in your garden.
Learn more about the Grassland Butterfly Conservation Program here and help support the work of our conservation team by donating to the Wildlife Conservation Fund.
