Photo by Jessica Mohlman.

May 1, 2023

Researchers Survey Dragonflies and Damselflies to Help Species Survive

Close up of a green and black dragonfly insect with while being held by a biologist. In the background is a shade and sun dappled mowed grassy area next to a gravel trail.
Photo by Amy Janik.

Dragonflies, Amy Janik recently has learned, are not as easy to catch as butterflies.

“Butterflies are rather slow and they like to perch,” said Janik, a research specialist at the National Great Rivers Research and Education Center, a unit of Lewis and Clark Community College in East Alton. “Many dragonflies, however, never land.”

Janik is leading a project to collect dragonflies and damselflies, in both their adult and larval stages, across Illinois. Collectively, dragonflies and damselflies are called odonates. Dragonflies are generally larger with thicker bodies and are stronger fliers than damselflies. Dragonfly eyes take up most of the head, but there’s a space between the eyes in a a damselfly. Dragonflies typically holds it wings out like an airplane, while damselflies fold them in.

“We want to know what species of odonates occur in Illinois, so we’re doing a state inventory,” Janik said. “Using insect collections from museums and data submitted by community scientists, we can see where odonates were found in the past and focus our fieldwork on broadening the knowledge of current distributions of odonates throughout Illinois.”

She and other researchers conducted a pilot season, visiting 14 sites in August 2022 and in April 2023, will initiate the full study with plans to visit 60 sites in the state. The focus of the study sites will be on areas where few data on odonates have been collected, for example the Shawnee National Forest in southern Illinois and some location such as around Alton, Champaign, Rockford and Galena. Funded through an Illinois Department of Natural Resources State Wildlife Grant the goal of the project is to visit four regions in Illinois during three different time periods to account for various odonate flight seasons and sampling 6 to 9 sites in each region. The sites will be sampled three times in a week to get a full picture on what might be occupying a site at that time frame. Researchers are collecting larvae, the immature stage of the odonates, which live in water, as well as adult odonates on the wing or perched. Visual surveys are also being conducted in order to account for any hard-to-catch adults.

A close-up of a green and black damselfly insect with four clear long wings folded over its back and long abdomen. The damselfly is perched on the finger of a biologist.
Photo by Amy Janik.

“Previous research in the field of entomology has documented the fact that insects are declining worldwide,” Janik said. “We don’t have an updated distribution account of the dragonfly and damselfly species in Illinois and can’t create management plans and protect these insects if we don’t know what species exist in the state. We also want to know what type of variables influence where a species is found. When we go out into the field, we record habitat variables such as dominant vegetation and any type of plants they may to choose to perch on. In a stream, we look all those variables that could influence the water quality, such as turbidity and pH.”

The information collected will be used by Janik and others on the team to create a detection model that will allow researchers and land managers to determine which odonate species might be present at other locations with similar habitat variables that have yet to be surveyed. They’ll also work to discover which odonate species are more tolerant as well as more sensitive to pollution.

“Odonates first appeared in the fossil records some 250 million years ago,” Janik said. “There are many families we recognize that were present before the dinosaurs and long outlasted them.”

Odonates function as part of the food cycle, contributing to the health of an ecosystem.

A biologist kneels on a shoreline and reaches into a stream to collect a sample in a spring woodland. Trees are leafing out and green understory plants are growing.
Photo by Amy Janik.

Fish and other aquatic organisms eat odonate eggs. Then the eggs become nymphs or larvae, which eat mosquito, mayfly and odonate larvae as well as other small aquatic organisms. Adult odonates eat mosquitoes, flies and “any insect that is flying around them, as well as other odonates,” Janik said. The adults then serve as food for bird such as flycatchers, swallows and swifts.

Janik explained that biologists and community scientists have gathered data on butterflies and birds in Illinois for a long time, but odonate data has lagged, likely because it’s more challenging in some ways. For example, odonates spend most of their lives underwater as larvae. The female lays eggs in water or on aquatic plants. The eggs hatch and become larvae. Hatching occurs five to more than 200 days after eggs are laid, depending on the species, and larvae will develop underwater from about a month to eight years, depending on the species. When they finally reach adulthood, odonates often live only a few weeks to a couple of months.

To catch nymphs, researchers scrape a net along stream beds and ponds in a transect, a predetermined place to take the samples.

Some of the best habitats to find odonate larvae are riffles, or the shallow moving sections of a stream. When scooping up odonate larvae, researchers also inevitably collect other aquatic organisms, such as crayfish and water scorpions.

A biologist holds a tiny macro invertebrate  in the palm of her hand. In the background is a wetland.
Photo by Jessica Mohlman.

Identifying larval nymphs, as well as some adult odonates, requires microscopic, detailed work. The protocol is to collect one voucher specimen of each adult odonate. After preserving and identifying the larvae and adults, a collection can be created that can be used as training kits for volunteers, or given to museum collections, such as one at the Illinois Natural History Survey, Janik explained.

Preserving, collecting and identifying odonates can be tricky, and sometimes frustrating, Janik admitted.

“But it’s worth it,” she said. “The most important thing is we want to protect these species, and the only way to do that is to get all the information we can and protect the habitats that these organisms use.”

Janik added community members interested in supplying data on odonates, can join Odonata Central or iNaturalist where they can upload photos and data regarding the species they’ve seen.

“Scientists do use that information,” Janik said. “Those databases are very important to us.”

Sheryl DeVore writes environment and nature pieces for regional and national publications and has had several books published, including “Birds of Illinois” co-authored with her husband, Steven D. Bailey.

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