indicator species

The Educational Value of an Insect Pond

If you’ve kept up with my last 4 posts, you know that I’ve built a pond at the Biosphere 2 as part of the fellowship I have through B2. Because I’m an aquatic entomologist, I built the pond specifically to attract insects. For more details on how the pond was installed, why I chose to include particular things in the pond, and suggestions for building your own insect pond, see my previous few posts! Today I’m going to talk about my educational display as a whole, the experience the pond was built to be a part of.

As I said in my first post in the series, I believe the best way for people to learn about aquatic insects is to see live insects. The focus of my display is my pond so that B2 visitors can see live insects swimming around and doing the things they normally do. If everything goes as planned, the pond will attract several insect species (including several beetles, mayflies, backswimmers, water boatmen, bloodworms, etc) from the surrounding area that will then colonize the pond. However, simply having people look at the insects has almost no educational value. To actually teach visitors something about the insects they find in the water, I created educational signs and identification guides.

My signs focus on two different topics, aquatic insects of the Sonoran Desert and dragonflies and damselflies:

Aquatic insects sign

Dragonfly sign

I know you can’t read the text in the signs, but let me tell you a bit about them. The aquatic insects sign focuses on something that is related to the work that I do: how the types of aquatic insects you find in a body of water can tell you important things about that body of water. Aquatic insects are found in almost all exposed freshwater, from a huge river to the water that collects in the base of your flower pots. Aquatic insects also depend on the availability of water for their survival and reproduction. This makes them excellent indicator species, species that tell us about the characteristics of a particular aquatic habitat.

In my aquatic insects sign, I discuss two different things that aquatic insects can tell us: how clean the water is and whether the water normally flows or not. Many federal, state, and local governmental organizations rely on insects to tell them valuable things about how clean the water is. Over the past 30 or 40 years, scientists have been observing insects they find in different types of water and assigning them pollution tolerance values. These tolerance values are based on the characteristics of the water in which the insects are typically found and can be inputted into mathematical formulas to tell an agency how clean the water is. I’ve done several projects that use insects as indicator species of aquatic habitat quality and it is a valuable means of quickly determining how clean the water is. I’ll discuss this idea further in a future post.

Insects can also tell us whether the water usually flows or not. Most aquatic insects have a preferred habitat, the place they most like to live. When you see enough habitats and collect enough insects, you start to see patterns in their distribution. For example, the insect called a hellgrammite (the larva of the dobsonfly) is usually found in fast flowing, relatively cool water. It is also long-lived for an insect, spending about 3-5 years underwater before it pupates and then emerges as an adult. If you find a hellgrammite, you know that the water in the system generally flows year-round and is often cold because they require 3-5 years of fast-flowing, cool water to survive. Knowing which insects belong in which types of conditions can tell you a lot about a system based solely on the insects you see in that system. It is also possible to tell whether disturbances have occurred in a system by looking at the insect population. For example, if you were to look into a pond and find a hellgrammite you might suppose that the area has been experiencing a drought, perhaps drying a flowing stream sufficiently to form ponds. A hellgrammite wouldn’t normally be found in still water, so you know there’s something abnormal going on in that system.

My dragonfly sign focuses on my favorite insects, the dragonflies. It’s a simple sign that talks about the life cycle of dragonflies (they are hemimetabolous insects, so they have three life stages – see my post on metamorphosis for more detailed information) and how to tell the dragonflies and damselflies apart (see my posts on how to tell them apart as adults and nymphs for more info on this topic).

Both signs introduce a topic, pose a question for the visitor to answer on his or her own, and then directs them to identification guides that will help them identify the things they are most likely to see. The dragonfly sign asks visitors to look for dragonflies and damselflies in the places they are most likely to be and suggests that they identify any they observe using the dragonfly ID guide. The aquatic insect sign asks them to look into the pond to see which insects a typical Sonoran Desert pond, one that contains still water year-round, will contain. They are encouraged to use the aquatic insect ID guide to identify the insects they find in the water. Both guides include photos, the scientific and common names of the insect, some of their obvious identifying characteristics, and suggestions for where to look for them in the pond. The ID guides were printed in color, laminated, and hung off the side of the pond via binder rings for easy access:

The ID guides hanging from their hangers on the pond.

I hope they will get good use for several years! I have also made the ID guides available here for people to download if they wish. This introduced all sorts of copyright issues for the images I was originally intending to use, some gorgeous line drawings from an aquatic entomology book that is otherwise dated, so I ended up using photographs instead. Most of the photographs are my own, but I would also like to thank Bob Behrstock for providing images for most of the damselflies that I was missing. Be sure to check out his amazing insect photographs on his website! To download the ID guide files, please see my Educational Materials page. I will leave them archived here for as long as I am able.

And that wraps up my pond series for now! I’ll give a brief update on how the pond is doing in May after we have the final meeting for my cohort of Biosphere 2 Science and Society fellows and I have a chance to check up on it, but I think my pond is largely on its own at this point. All in all, I thought the pond-building experience was a good one. It ended up being a lot more work than I’d expected because I got less help at every stage than I had expected, but what doesn’t kill you makes you stronger and better educated, right? I learned a lot while building this pond and it’s an activity I would highly recommend that other people try. If I could do it, anyone can! It wasn’t all that expensive (about $600 for the tank and all of the supplies) and the above ground tank made everything pretty easy in the construction phase. Plus, you get to use power tools, and that’s always a good thing. You can’t beat the end product – a gorgeous pond full of green plants and amazing insects in your yard. I am looking forward to the day when I can build a pond in my own yard and enjoy the dragonflies and other insects that will use it. I’m sure it will be even easier the second time around!

Until next time, I leave you with a photo of my entire display (pond, signs, ID guides, and all) in the lovely orchard courtyard of the B2. If you have a chance to visit B2 and check it out, I hope you’ll stop back here and leave comments! I’d love to hear what people find in the pond and how they like the display – and I’m always happy to answer questions too.