DELMARVA ALMANAC

A Conversation About Dragonflies & Their Kin

by Dave Wilson

Dave Wilson shares his conversation with Jim White from the Delaware Nature Society about dragonflies and their kin.

Dave Wilson:
In the studio today we have Jim White from the Delaware Nature Society and co-author with his wife, Amy, of The Amphibians and Reptiles of Delmarva. Jim is a native Delawarean and has worked for the Delaware Nature Society for 33 years where he is currently serving as the Senior Fellow for Land and Biodiversity Management. He teaches herpetology at the University of Delaware. Jim just happens to have remarkably extensive knowledge about some of our flying insects friends, namely damselflies and dragonflies. Today we are going to talk to him about these mysterious and remarkably beautiful group of invertebrates.Jim, welcome.

Jim White:
Thank you. It's good to be here.

Dave Wilson:
First off, can you tell us how you learned about dragonflies and damselflies and how old these species are?

Jim White:
Well, I was lucky enough to meet a friend of mine, no relation, Hal White, who is a retired University of Delaware professor, about 15 years ago and ever since we've been going on field trips and he's taught me a lot about damselflies and dragonflies. He also is the author of "The Dragonflies and Damselflies of Delmarva" which was produced by the Delaware Nature Society. I was able to help him a little bit on that book with photography and actually on some of the field trips.

Now, the difference between damselflies and dragonflies; that's a question I often answer. They're both in a group called odonates or actually class of odonata. They are very closely related, however, in the field it is easy to tell them apart. Damselflies, as their name implies, are a delicate insect. It flies very slowly. It tends to hold its wings above its back which is kind of interesting. They also have eyes out on the stalks. If you look very closely at the damselflies you'll see the eyes are way out on the side, almost like a blue crab, how they have them on a stalk. Dragonflies, on the other hand, tend to be robust. They are very strong fliers. They get a lot larger, at least here on Delmarva. They hold their wings when they are perched, perpendicular to the body, very flat. I'm sure most people know the difference, probably, when they see them in the field.


Dave Wilson:
Do you know how old some of these species.....I guess the order really is.....I remember as a kid looking at my dinosaur book and seeing these giant dragonflies, it seems like this is an old order of insects.

Jim White:
Oh, yeah, actually they predate the dinosaurs. Some of the ancestors of today's odonates are around 300 million years ago, so that predates dinosaurs almost by 100 million years. So they've been around for a long time and I don't know if you remember, some of those early odonates were large. Some of them had wingspans up to a meter. I'm wishing they were still around.

Dave Wilson:
What would an odonate with a wingspan of a meter eat, is the question, I guess.

Jim White:
They probably ate insects mainly; larger insects. Insects were larger back then. The dragonflies were larger for one particular reason. There was a group of animals that had not evolved yet and that's the birds. So after the birds evolved, dragonflies tend to have gotten smaller. They had to be very much quicker in flight so they became smaller. And today the largest dragonfly probably only has a wing span of about 7".

Dave Wilson:
What are some of the most common species we have here on Delmarva?

Jim White:
Well, one of the most common; it's also one of our larger ones, is the green darner. This is a really beautiful insect. It has a really interesting life history because it is one of the few insect species that actually migrates. It migrates from the south up here to the north every year and then its offspring migrate back so it's very commonly observed by people. But there are many other species that people see around ponds that are very common.

Dave Wilson:
What are some of the most sought after and beautiful dragonflies and damselflies?

Jim White:
Well, there are several that us and the folks who really go out and look for them are always searching for. One of them is the elfin skimmer. It is a dragonfly, but it is actually one of the smallest dragonflies in the world. It is a really gorgeous little species. There are several others that are just very, very beautiful, the Needham's skimmer which is very common, actually, especially down here along the coast. It is one of those species that would be great to photograph. It is really beautiful.

Dave Wilson:
Do you have a sense of how many species of dragon and damselflies there are on the peninsula

Jim White:
Yeah. There's over 130 that have been actually observed. Now some of them aren't here today. They've been extirpated probably and some of those are probably migrants that just happened to blow in here on a storm.

Dave Wilson:
What do most damselflies and dragonflies eat?

Jim White:
Well, as adults they all eat flying insects. So they eat flies, they eat butterflies, they eat bees, some of them. They eat all different types of flying insects. Some of the smaller ones actually eat mosquitoes.

Dave Wilson:
Can you talk about their life cycle a little bit. I know dragonflies and damselflies life cycles are very interesting; beginning in water and I think listeners would like to hear about some of that.

Jim White:
Right. All the species here on Delmarva begin in the water. The females lay the eggs in the water or very close to the water. As the eggs hatch, they hatch into larvae. These larvae are completely aquatic and that larvae can actually live two or three years. And that's a little different than the adults. The adults will live only for one season: one spring, summer, fall. So their facing a double life; the larvae in the water catching aquatic insects and then transforming to the adult.

Dave Wilson:
Do these species live in a variety of water types. In other words, do they need permanent ponds or temporary ponds or creeks and rivers or is there a preference based on species?

Jim White:
That's a very good question. It all depends on the species. Some of the species are generalists. They can live in just about any kind of still water, ponds. It doesn't even need to be that clean. They can be actually in water that is somewhat polluted. Then there are other species that are specialists of very clean, cool streams. So, yes, there's a very large variety of what types of water they need.

Dave Wilson:
A lot of frog species need fish less or relatively fish less ponds. Is this true also for dragonflies and damselflies?

Jim White:
There are some species that prefer ephemeral pools or fish less pools. But the vast majority of them seem to be able to deal with some sort of fish pressure.

Dave Wilson:
Are their certain birds that target dragonflies and damselflies?

Jim White:
Oh, yeah, all flycatchers, the eastern phoebe, the eastern king bird. Often when you sit and watch an eastern king bird, he'll snag a dragonfly.
Dave Wilson:
What kind of threats do damselflies and dragonflies face on the peninsula?

Jim White:
Well, the biggest threat is habitat loss and water quality. Water quality, whether it be the stream that they lay their eggs in has become polluted or even too much sun reaching that stream because the forest has been cut down around the stream. Very serious, though, as water quality degrades the diversity of odonates goes down.

Dave Wilson:
Where can people find out more about these species?

Jim White:
Well, Hal White's books are a great resource for Delmarva. He, what he did, he took his 50 years of studying these insects on Delmarva and he took his experiences with each species and he wrote vignettes about these species; about the life histories. Just an amazing amount of information in that book. I think that would be the first book I'd recommend and then there are several others. If you go online there are some books that have just been published about the Eastern United States. So you'll find a lot of resources on the web.

References:


Delaware Nature Society

Natural History of Delmarva Dragonflies and Damselflies
by Harold B. White III

Common Dragonflies and Damselflies of Maryland

Checklist for known dragonflies/damselflies
and Butterflies/Skippers for Assateague Island National Seashore


Dragonflies and Damselflies of Maryland

Delmarva Dragonflies and Damselflies

Dragonfly and Damselfly Day