The Dragonfly Woman is 1 Year Old!

It’s official – today marks one whole year of my writing The Dragonfly Woman!  I have to say that this has been a very rewarding experience for me.  It’s been great fun interacting with the other insect bloggers around the world and I love getting questions from readers.  It’s been a much more interactive adventure than I would have anticipated when I first started this blog and I couldn’t be happier about it.

Although the fellowship that prompted the creation of this blog is now over (and honestly, I never would have gotten this blog off the ground if I hadn’t gotten the fellowship – thanks Biosphere 2!), I intend to keep blogging.  I really love doing this and feel like I’m doing some good,spreading some good insect vibes to those who read my posts, so why not?  And now that I’ve been doing this for a year, I know what I’m doing, I’m motivated to do it, and I feel like I’m really getting something out of it personally and professionally.  Hopefully you, my readers, are getting something out of it too!

Because I’m anal, I have plans to make my blog better in the coming year.  Not that I think I’m doing anything wrong now, but there is always room for improvement.  So, I intend to make some changes and/or additions to my blog this year.  These include:

1) Posting more often. This might not happen right away as I’m in the middle of writing my dissertation, but my goal is to start posting 3-4 times a week rather than once a week like I have been.  I can’t make all of my posts long and detailed if I do this, so I plan to keep doing one detailed post a week as I’ve been doing and make the other 2-3 posts shorter pieces.  This way I can share information I find interesting right away rather than simply adding it to my ever growing list of things to talk about in my blog.  Aquatic insects rock and I want to share them with the world!

2) Getting my gallery up and running.  I have a page for it, but I haven’t had the time to go back and plop my photos into the gallery.  It’s going to take some time and effort, but I think it will be worth it in the end.  I’ll have a table of contents as well as a gallery of thumbnails so that readers can find images easily.

3) Provide more educational materials. I love developing curriculum.  I even had a job to do just that at an extension office in Colorado once.  It was great!  Teaching people about insects is the goal of my blog, so why not make some formal activities available?

4) Making my blog more interactive.  The best part of my blog is the information, questions, and comments I receive from my readers, all of the fabulous interactions I have with the people for whom I write this blog.  Through my blog, I have gleaned several new outreach opportunities, from providing dragonfly photos to an Audubon educational facility in the Phoenix area to being asked to provide some giant water bug footage for an upcoming program on Animal Planet.  I have already added a contact form so that people can send me e mails to ask me questions or get more information about topics I’ve blogged about.  Please feel free to start using it to contact me!  I would also like to start posing questions and creating polls on my blog that people may respond to.  Improving the interactive capacity of my blog also ties into my last idea…

5) Hold contests. Who doesn’t like to get free stuff?  And free insect stuff is even better!  (Well, it is if you’re an entomologist or insect enthusiast at least…)  To that end, I now announce my first contest:

I’m curious how many people actually read my new posts each week.  I’d like for everyone who reads this post to leave a comment.  If you have any suggestions for how I might improve my blog or topics you would like to see me write about over the next year, feel free to include those in your comment, but a simple “hi” will suffice.  I will randomly select a winner from all of the comments received over the next week – you have until June 4th to respond.  I’ll post name of the winner on my blog and contact him or her to get a mailing address.  The winner will then receive a matted, frame-ready Dragonfly Woman original insect block print in the mail!  The print will be hand printed in black ink on white acid-free watercolor paper by me, the Dragonfly Woman, using a hand carved linoleum block of my own design.  And, you even have a choice of insects: damselfly (Argia sp.), caterpillar hunter beetle (Calisoma sp.), scarab beetle, ant (Polyrachis sp.), or giant water bug (Lethocerus medius).  Good luck to everyone who chooses to enter!

Next week I’m going to do a post with an update on how the pond I built at the Biosphere 2 is doing a month after it’s installation.  The following week I will be going to a conference in Santa Fe, the joint meeting of the American Society of Limnology and Oceanography and the North American Benthological Society.  While I’m there, I will write a new post daily to highlight my favorite talk or poster of the day.

Thank you all for making my first year at The Dragonfly Woman blog so thoroughly enjoyable!

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

More giant water bugs eating

I’ve been super busy with work recently and haven’t had time to put together one of my normal, long-ish blog posts.  But, I wanted to get SOMETHING up this week!  This will be short on words, but hopefully big on the wow value.

Several weeks ago, I wrote a post on giant water bugs eating and included a video of the medium sized species we have in Arizona (Abedus herberti) eating a mealworm that I gave it.  That post details how giant water bugs eat, so I recommend that you check it out for more detailed information on what you’ll see here.  Abedus herberti isn’t nearly as big as another Arizona native, Lethocerus medius, and while it’s mode of eating is still impressive, it’s nothing compared to what L. medius can do.  Species in the genus Lethocerus are the largest true bugs on the planet and are real powerhouses when it comes to taking down vertebrate prey.  These bugs are big, so they can eat really big things like snakes, turtles, frogs, fish, and birds.  So, in my insect behavior class we fed a goldfish to the Lethocerus medius we’d been experimenting with all semester, a goldfish that was about the same length and likely much heavier than the bug.  The bug hadn’t eaten for over a week to prepare it for the goldfish demonstration.  This was the result:

Now if that isn’t the coolest thing ever, I don’t know what is!  This right here should be enough to convince anyone that giant water bugs are the best insects one Earth.  (Okay, okay – so I’m a little biased!)  Now normally this bug would just sit in one spot and wait for food to swim by (they’re called sit and wait predators for a reason), but not this one.  He was so hungry he actually hunted down and captured his food before eating it.

Next up will be my one-year anniversary post.  I can’t believe I’ve been at this for a year already!  This calls for a celebration.  I might even give something away as a reward for sticking with me this long…

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

The Jesus Spider

Now that I’ve finished up my pond series, I been trying to decide what to write about next.  A From the Literature, since I haven’t done one in ages?  Perhaps another identification lesson?  Those all seem awfully heavy after the long pond series.  I eventually decided that it’s time for another story from Dragonfly Woman’s childhood.  This is the story of the Jesus Spider.

Though I spent the first 9 years of my life in Arizona, I spent most of my childhood living in Colorado.  My dad LOVED Colorado (he was thrilled when we got to move there) and my parents were outdoorsy, so we spent nearly all of our weekends in the mountains fishing, collecting minerals, or camping.  My sister and I loved to swim and didn’t have access to a pool, so as soon as the ice on the rivers melted, we were in the frigid water splashing around on our frequent  family fishing trips.  I now realize that we were insane as children and I’m shocked we never got hypothermia.  I can tell I’m getting older because I find that kind of water downright painful now and wouldn’t even dream of going for a swim!  Still, it was a great way to grow up.

swimming

The Dragonfly Woman swimming during a spring break in high school.

My grandparents lived in Tucson and we made a yearly trip to visit them, usually during spring break.  The best part of going to Tucson was always the warmth.  After a cool winter in Colorado, the lovely warm weather in Tucson was most welcome.  We could wear shorts and sandals in Arizona as we heard about 6 foot snowdrifts from friends in Colorado.  We loved it.  Because we spent so much time in those frigid rivers, the “cold” outdoor pool at my grandparents’ house, the one no sane Arizonan would ever get into, felt like a hot tub to us.  My parents were hard pressed to keep us out of the water.

dead lizard

The next to worst thing my sister and I ever pulled out of our grandparents' pool.

My grandparents lived near the edge of town in an area that has a lot of wildlife.  The pool was always a bit of an adventure because you never knew what you might find in it.  My grandparents told us stories about fishing drowned rattlesnakes and pack rats out of the pool.  Every once in a while there would be some largish mammal in there.  The worst my sister and I ever found was a large lizard trapped in the drain basket, so we lucked out.  The main wildlife encounters we had in the pool were insects, which I was thrilled with as an entomologist-in-training, and spiders.

Now I’ve always had an intense and irrational fear of spiders.  I don’t know exactly where it comes from, but my dad tells a story about an encounter I had with a black widow when I was a very small child (like 1 1/2 or 2) that I think might be the source of my fear.  My dad waged an all out, no holds barred war against the black widows in our yard when we lived in AZ.  We had tons of them and my parents had two small kids, so he wandered the yard armed with Raid nearly every day.  He also taught me at a very early age not to touch them because they were venomous.  One night he checked on me in my crib after I called for him and I told him that there was a very large spider on me.  He kept telling me that I was having a dream and that there was no spider.  I kept insisting and got more and more frantic about it, so he eventually decided to prove that there was no spider.  Imagine his surprise when he found the biggest black widow he’d ever seen!  It had been crawling around on my blanket near my legs.  I had noticed it and apparently become scared (I knew they were dangerous after all), so I’d called my dad to come rescue me.  I’ve been terrified of spiders nearly my whole life, so I have a feeling this might have been the reason.  My sister doesn’t have any excuse.  :)

spider

The stuff nightmares are made of.

Back to the pool.  Every time my sister and I found a spider in the pool, we would knock it into the water so it would get trapped and drown, so it couldn’t “get” us.  Pretty stupid really, but we were kids.  One day, we hopped into the pool and saw the biggest spider we’d ever seen clinging to the walls of the pool.   I have no idea what it is, but that’s it in the picture – I found one in my backyard a few years ago.  these things are BIG!  If anyone knows what it is (the idea of keying it out myself makes my skin crawl), leave a note in the comments section!  I’d love to know what it is.  Needless to say, a monster spider with a 4 inch leg span that might crawl on one of us while we swam was the worst thing imaginable, so we decided to knock it into the water to protect ourselves.  We splashed the spider vigorously from a few feet away.  It took a while to dislodge it, but it eventually came loose and fell into the pool.  We hooted in triumph as we watched the spider scourge flounder in the water.  Yep, we were spider trapping studs and we congratulated ourselves for vanquishing our foe.

Until, that is, the spider pulled itself up onto the surface of the water, paused for a moment, then RAN  toward the other side of the pool like it was running across pavement!  This would have been bad enough except that were in water up to our necks and were positioned squarely between the spider and the wall where it was headed – it was headed straight for our faces.  I believe there may have been some panicked, girlie screams as we frantically tried to get out of the spider’s path and we watched in horror as its freakishly long legs missed us both by mere inches.  It reached the other side and crawled entirely out of the pool, ran across the courtyard, and disappeared over the wall.  Still, that was it for the pool that day.  For the remainder of the trip, we checked the entire perimeter of the pool for spiders before we got in.  We also stopped splashing spiders.  Clearly we were being punished for our spider drowning proclivities and karma was coming back to bite us in the butt.

I’m sure the spider was harmless as it was WAY too big to be any of the venomous spiders we have in Tucson, but I can still vividly remember the sight of that monster running across the surface of the water straight for my face.  The memory still gives me chills, though I can certainly see the humor in the situation now as well.  As an aquatic entomologist, what I don’t get it how the spider was able to stay on the surface of the water for so long.  This was deep water as far as the spider was concerned, about 5 feet.  It ran about 20 feet from one side of the pool to the other.  It PAUSED before it started running.  How was it able to keep itself from falling in?  I know there are lizards that run on the surface of the water, but they have to keep moving to do so.  It still seems strange to me that a spider that large and heavy could skip across the surface of the water so easily.  I still have no idea how it managed it.  I’ll figure it out someday.

So there you have it.  A giant spider walking on water.  The Jesus Spider!  My sister and I named it the Jesus Spider the moment it crawled out of the pool and that’s what it will always be for us.  And because it’s late and I’m writing about the stupid spider, I’ll probably have a spider nightmare tonight.  I used to have them all the time, but it’s been a while…

Next time I promise to write something a little more scientific!  And I hope to start writing two posts a week instead of just one too.  My blog’s almost a year old, so it’s time to pick up the pace!

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Building a Garden Pond for Aquatic Insects, Part 5

pondThe 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

Aquatic insects sign

dragonfly 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:

ID guides

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.

educational display

The final product of my permanent educational display at the Biosphere 2.

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Posts in this series:

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Building a Garden Pond for Aquatic Insects, Part 4

pondWater, Electricity, and Avoiding Skeeters!

Now that I’ve gone over how I installed my pond at the Biosphere 2 and the things I added to it to keep the water nice and the bugs happy, I wanted to discuss a few final things: keeping my pond low-maintenance while keeping the water clean and mosquito-free.  In the interest of keeping this post within my personal word limit, I’ll finish up the pond series in my next post with some brief info about the display as a whole and the educational experience that my pond represents.

I live in a desert.  By definition, a desert is a place where there is more evaporation than precipitation, so any time you expose water to the air it tends to dry up.  Having to top the pond off every day wasn’t going to work because the Biosphere 2 doesn’t have the personnel available to do it.  Instead, I installed an automatic filling system so that the pond would refill whenever the water levels dropped so that no one will need to keep an eye on the water levels.

This was a rather simple task.  The B2 staff extended a water line from the agricultural module into the courtyard where my pond is located.  All I had to do was connect the 3/4 inch PVC pipe they left (and dug a trench for – thanks to the B2 maintenance staff for the help!  I really appreciate it!) to my pond via a simple float valve, the kind commonly used in evaporative coolers.  So, I made a trip to Home Depot and bought the supplies: a float valve, an threaded PVC connector, some PVC glue,  several brass adapters that would connect the 3/4 inch PVC connector to a 1/4 inch plastic hose (including a compression fitting), and teflon plumber’s tape.

float valve

My pond's plumbing. The float valve is the blue float in the background and you can see the hose connector on the outside of the tank.

I fitted the PVC connector onto the PVC pipe with the glue and let it sit overnight.  The next day, I wrapped all of the threads of the adapters with teflon tape and screwed them together and onto the PVC connector.  I then ran the hose up the side of the tank and connected it to the compression fitting on the float valve.  Finally, I inserted the float valve through a hole I drilled into the tank (okay, the second hole – I completely screwed up the first one, as you can see in the picture…) and turned the water on.

And got sprayed right in the face while I scrambled to turn the water back off.  After several more attempts to get the hose properly attached to the compression fitting on the float valve (let’s just say it was more than 10 attempts and leave it at that), I got everything connected and didn’t have any leaks.  I buried the pipe and the hose, piled a bunch of rocks up along the exposed part of the hose on the outside of the tank, and adjusted the float valve to fill the tank to the level I chose.  Now, every time the water level drops below that level, it opens the water valve, filling the tank automatically!

In spite of the problems I had getting the float valve and the hose connected properly, it was pretty easy to do the plumbing for the tank.  If you choose to build a pond at home, an automatic filling system seems to be an easy way to save yourself a lot of maintenance on your pond.  If you have a spigot that can be devoted to your pond, it is very easy and cheap to connect a float valve to it using the same method I used for my pond without doing any major plumbing work – you just leave out the PVC parts.  If you don’t have a spigot available, you will need to extend a pipe specifically for your pond and connect it to a float valve for automatic filling.

pump housing

The housing for my pond pump. You can't see the rock under the pump, but it's there.

The other thing the B2 staff had to do for me was extend an electrical line from the agricultural module so that I could install a pump to keep the water flowing in the pond.  You don’t have to have flowing water, but there are several reasons why you might want to.  For one, it circulates the water and causes turbulence.  This helps boost the oxygen level of the water: the more turbulence, the greater the oxygen load of the water.  I also wanted to maintain flowing water to avoid breeding mosquitoes, but more about that in a moment.

If you read my last post, you know that I stacked some cinder blocks to build a housing for my pump.  I did this so that the pump would be largely enclosed to reduce the amount of debris that might clog it.  I put a rock at the bottom of the cinder block column to keep the pump off the ground so that the silt that settled on the bottom of the pond wouldn’t get sucked into the pump and redistributed into the water.  I connected the tubing to the pump and dropped the whole thing into the housing, trimming the hose so that it extended about 10 inches above the proposed water level.  Once I filled the pond up, I stacked flat rocks over the top of the pump housing, partly to keep debris from falling into the housing, but also to provide something for the water to run over.  The tube from the pump ends just out of sight under the top rock.  This is the result:

pond waterfall

The waterfall in my pond. You can see the water flowing out of the pump's hose in the center of the image.

I think it looks rather pretty, but the mosquitoes are the main reason I though a pump was essential.  Mosquitoes are a big problem in Arizona and are attracted to water to lay their eggs.  Fortunately, there are several ways you can prevent mosquitoes.  First, mosquitoes don’t like to lay their eggs in moving water, the rationale behind the pump.  Mosquito eggs are susceptible to being washed downstream and the larvae don’t like flowing water, so female mosquitoes generally only lay eggs in still water.  My pond pumps about 300 gallons (over half of the volume of the pond) per hour.  This is enough to keep the water moving across the entire surface of the pond at all times.  Second, mosquitoes don’t like to lay their eggs in direct sunlight, as I recently learned from a mosquito biologist who works in my department.  My pond is in full sun for about 6 hours a day.  Third, you can use BT rings to kill mosquitoes in the pond as necessary, though these will also kill the other fly larvae  and potentially some of the beetles growing in the pond.  BT is the colloquial name for the toxin that the bacteria Bacillus thuringiensis produces.  This toxin readily kills a narrow range of invertebrates, including flies, butterflies and moths, some ants, bees, and wasps, and some beetles.  It has been used in powder form as an alternative to pesticides in organic farming and has been genetically engineered into the genome of several crop species (including cotton and corn) to decrease the amount of pesticides used fighting agricultural pests.  Since mosquitoes are flies, dropping BT ring pieces into the pond now and again should keep mosquitoes in check.

One final method for controlling mosquitoes involves a biological control method: mosquitofish (Gambusia affinis).  While many pond enthusiasts favor using fish in the war against mosquitoes and in spite of the fact that mosquitofish are very effective mosquito larva predators, I didn’t want to use them in my pond.  They aren’t native to Arizona and I believe they are problematic are in many of our waterways, so I am opposed to using them in case they are accidentally spread to new systems (it happens).  If I have fish in the pond, it will also drive the nitrogen levels, ammonia in particular, to levels that require control.  This involves installing a filter, which further requires swapping out filters, making sure it’s working properly, testing the water for ammonia, etc.  That is much more maintenance than my pond will receive.  So, it worked out that adding the fish I don’t like anyway wasn’t feasible with the low-maintenance requirements of my pond.  I am relying on the other three methods instead.  An added benefit of building a pond to attract insects is that it will attract several mosquito hunting insect predators as well, including giant water bugs, dragonflies, and backswimmers.  The very insects I hope to attract to my pond might control the mosquito population themselves!

Next time I’ll complete my pond series with a brief look at the educational components of my pond, including the identification guides I developed.  Seeing as educating the public about aquatic insects was the whole point of building the pond, I thought the topic deserved its own post.  I hope you’ll check back!

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Posts in this series:

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Building a Garden Pond for Aquatic Insects, Part 3

pondChoosing and Installing Substrates

Last time I discussed how I chose a location, planned, and installed the container for the pond I recently built at the Biosphere II.  My pond is designed to be low maintenance and attract aquatic insects, so the things that I chose to put into the pond were important – different insects look for different things when choosing a home.  Today, I’m going to go over the things I chose and why I chose them.

There were two main things that I wanted to balance in my pond: diversity of insects and the quality of the water.  Many insects depend on a particular water quality to survive, but the pond is also an educational display.  Being able to see into the water is a good thing if you’re trying to convince people to look for the bugs!  I also wanted to provide many different objects in the water to attract as many different types of insects as possible.  Choosing the right plants and ornamental/landscaping features are important if these are your goals.

I started by adding a tick layer of pea gravel, small cobble, and large cobbles to the bottom of the pond (large cobbles not pictured):

pond rocks

Rocks in the bottom of the pond.

Many insects like to sit on the bottom of ponds and want things to hold onto.  There are several species of insects that I find only on rocks, so I wanted to make sure there were plenty available.  By including three different sizes of rocks, I created 3 different habitat types that might attract three or more different types of insects.  These rocks were also very dusty and I knew I would end up with a layer of fine sand or silt at the bottom of the pond once it was filled, creating yet another space in which some insects will live.

Next, I added the cinder blocks you see in the image.  These were installed to provide a platform onto which I could later put my plants.  I also needed to create a space that would be relatively silt-free in which I could put the pump that would circulate the water.  I’ll talk about the pump in my next post.

My field site!

An example of a natural pond experiencing a massive algae bloom.

Many people install a layer of garden soil on the bottom of their ponds so that they can plant plants directly into the pond.  While this most accurately imitates a real pond, I didn’t want to do this for one important reason: adding a lot of garden soils to the water introduces nutrients into the water.  While these are good for promoting plant growth, something you might desire if you are building a pond for growing plants rather than attracting insects, putting a lot of soil in ponds drive nutrient levels up.  This in turn promotes algae growth and can cause massive algae blooms (rapid reproduction and growth of algae) and causes problems in the pond.  Algae blooms tend to make the water very opaque (see image at right), which decreases the educational value of my pond.  The algae can also block the light from reaching any submerged plants near the bottom of the pond, potentially killing them.  Further, when the algae absorb most of the nutrients from the water, they die off in hoards, fall to the bottom of the pond, and rot.  The rotting process consumes oxygen, so the oxygen levels in the pond drop.  Sometimes this can kill the insects that live in the pond.

You can control algae with algaecides, but that is a maintenance heavy task and my pond needed to be low maintenance.  Instead, I decided not to put much garden soil into the pond to keep the nutrient load as low as possible.  Many aquatic plants can survive in rather low nutrient environments, so I planted the rooted plants in pots, then submerged the pots in the pond.  This had the added benefit of allowing me to keep the plants contained so that they wouldn’t spread and fill the entire pond.

Horsetail

One of my plants, a horsetail reed, in its pot.

I bought some of my plants (including the horsetail at left) and those all came pre-planted in soil.  For the plants that were donated and/or harvested, I largelyfollowed the recommendations of the Tucson Water Gardeners and used unscented kitty litter in place of soil and planted my plants in water plant baskets that I got from Home Depot.  I added a thick layer of kitty litter, a very thin layer of garden soil, and finished with a thick layer of kitty litter on top.  This way, the soil is held in place by the litter (soil can float to the surface if it’s not weighed down) and there is very little soil added to the pond, but enough nutrients for the plants to thrive.  I’ll give an update on how my plants are faring next month when I know how well it worked!

I wanted to include a variety of plants in my pond.  This makes the pond look nice, but the right balance of plants also contributes important habitat to a variety of aquatic insects and helps keep the water looking its best.  For the insects, I wanted to use several different types of plants: rooted marginal plants (those that have their roots in the water and the vegetation extends well above the surface), floating plants (rooted or unrooted plants that float on the surface), and submerged plants (plants that are entirely underwater).  The rooted marginal plants provide vertical habitat for insects that like to climb, such as damselfly nymphs.  Floating plants are great for obscuring insects that swim in the water column like beetles and backswimmers.  The submerged plants are great habitat for the insects that stay underwater all of the time and like to hide, such as mayflies.  Lots of different types of plants mean lots of different types of insects, so including a variety of plants was a priority for me.

The plants also contribute to the quality of the water in the pond in several important ways.  Submerged and floating plants contribute a lot of oxygen to the water as they photosynthesize, something the insects, especially those that live on the bottom of the pond and don’t go to the surface to breathe, need to survive.  (For more information, see my posts on aquatic insect respiration and improving aquatic respiratory efficiency.)  All of the plant species absorb nutrients from the water, keeping the nutrient levels down.  The plants also block the light from about half of the pond.  Low nutrients and low light are good things if you want to keep the algae population under control, so hopefully my plants will prevent huge algae blooms from occurring in my pond.

As far as the specific plants I used go, I used 9 different species.  For marginals, I used horsetails (Equisetum hyemale – an interesting plant), cattails (Typha latifolia), arrowhead (Saggitaria sp.), an unidentified rush species, and a yellow water iris (likely Iris pseudocrorus).  My floating plants include an unidentified floating plant I got from the University of Arizona’s Environmental Research Lab and parrots feather (Myriophyllum aquaticum – an invasive aquatic plant commonly sold as a pond plant that I only planted because it is FAR away from natural water sources).  My submerged plants are a type of hornwort (Ceratophyllum sp.) and a waterweed (Elodea sp.).  All of these are supposed to thrive in Tucson’s climate, so we’ll see how well they do at a slightly higher elevation.  (Thank you to the Tucson Water Gardeners for donation of the hornwort, waterweed, parrots feather, and arrowhead, and to the UAERL for the irises and unidentified rush and floating plant!)

I filled up the pond with a hose and put the plants in their pots into the pond.  The water was muddy when it was first filled, but the silt settled out pretty quickly – the water was clear a few days later when I went back to B2 to work on it again.  Good thing, because it didn’t look so great at first:

muddy pond

My pond, immediately after filling.

If you read my last post, you know that I had to make my pond safe for kids to be around, which involved installing a barrier.  The mesh you see just under the water is what I call the anti-drowning shield for my pond.  It’s not pretty and it was a beast to install (the worst part my the experience!), but it keeps kids out of the pond too.  It’s a good thing and necessary.

Next time I’ll talk about my pump, installing the water and the electrical components for the pond, how I’m combating mosquitoes, and the educational components of my display.  Later this month I’ll give an update on how my pond’s doing!  Hope you’ll check back!

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