Lynx Lake Dragonflies

About seven years ago, Margaret and I were going out to dinner when we noticed someone walking along the lakeshore in front of our cabin.  Thinking they might need some help, I walked down to our dock and found it was a group of researchers studying dragonflies.  I would have liked to have stayed and learn about their research, but it was Friday night and we were heading out for fish fry.  After finding they didn’t need any assistance, we left for dinner.  I have run into these researchers at the Lake a few times, and last summer we both had time to talk about their research in detail (more on that later).  One part of their research involved understanding dragonfly species diversity and the relationship to the flora of the Lake and shoreline.  A short, easy to read summary of that research is below, which is part of the author’s Ph.D. dissertation.  One of the 17 lakes studied in her research was Lynx Lake!

The above photo is a Crimson-ringed whiteface dragonfly (photo credit Alysa Remsburg)

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Dragonfly research in Vilas County, Wisconsin

Alysa Remsburg, PhD

UW-La Crosse Environmental Studies

The main reason so many of us enjoy northern lakes is the beauty of nature. We want to access the water, take in the scenery, and be good neighbors to the other critters sharing this habitat.  Only a handful of fellow inhabitants really bother us, and mosquitoes top that list.  I became a huge fan of dragonflies when I learned that this most graceful lake resident is also a useful mosquito predator.  When I learned that there are more than 160 different species of dragonflies and damselflies just in Wisconsin, I was fascinated to investigate what factors support greater species diversity in some places, and how lakeshore human residents might affect our neighboring insect residents.  With support from UW Madison, a National Science Foundation fellowship, and the Trout Lake Long Term Ecological Research Station, I set out to research how shoreline landscaping impacts dragonfly and damselfly communities in Vilas County lakes.

My fascination with dragonflies and damselflies (also known as Odonates) grew even greater as I realized that they spend most of their lifetime under the water, where they consume mosquito larvae and other small insects. That led to even more questions about how people using the lakes might influence dragonflies in both their aquatic and terrestrial life stages. Although dragonflies don’t eat plants, the structure of vegetation influences hiding, movement, and temperature regulation of these and other predators.

I surveyed Odonate larvae in the water and flying adults across 41 sites within 17 Vilas County lakes.  I selected half of the sites from developed areas and the rest from undeveloped forested areas.  I tested statistically which of the aquatic and shoreline variables correlated most closely with dragonfly counts and with the diversity of species.  Dragonfly species diversity was most closely associated with shallow underwater plants, suggesting that if we cut or treat aquatic ‘weeds,’ we lose some of our local biodiversity. Tall wetland plants such as cattails and rushes growing near the water’s edge turned out to be a strong predictor for the overall abundance of dragonflies, especially the clubtail dragonflies that I found most abundant as aquatic larvae.  Based on a controlled field experiment where I moved potted cattail plants to different shoreline sites, I observed that damselflies occurred in much higher abundances right after these shoreline plants were added.  

This research suggests that preserving or restoring shoreline and near-shore aquatic plants does influence the communities of Odonates with whom we share the habitat.  We already knew that promoting native plants near the water’s edge contributes to improved water quality by slowing the flow of nutrient runoff.  We now have an example of a charismatic, beneficial group of insects that will also benefit from less mowing at the water’s edge.