Well-Nigh Wordless Wednesday: Science

I do a fair amount of field work and I do a lot of behavioral work in the lab, so I don’t usually feel like the stereotypical scientist in the white lab coat.  Heck, I don’t even OWN a lab coat!  But now and then I work on something that looks so stereotypically like “science” that I have to laugh to myself just a little.  Case in point:

protein analysis

Protein analysis

Seriously, is there a bigger science cliché than a bunch of colored fluids in tubes?  This test tells me how much protein is available inside giant water bug eggs.  The darker purple, the more protein there is!


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Ode to My Bug Nets

me at Los Fresnos

Me at Los Fresnos in Sonora, Mexico, with my aquatic net.

Every entomologist, amateur or professional, should have a bug net.  Collecting insects is an important and informative part of the experience of being an entomologist and you need a net to do most of it.  Plus, if you’re going to be an entomologist, it seems only proper that you have that big symbolic icon of our science.  I mean, who’s heard of an entomologist without a bug net?  It’s just unnatural!

I bought my first bug net in 2005.  It’s one of those fancy compact jobbies that fold up for easy storage and travel.  I got the swanky red plastic handle to go onto the end of the pole for easy gripping.  I got an extension pole so my net is about 4 feet long, long enough to snag a dragonfly from the shore of a pond.  I love my net!  It makes me feel good to own it, happy to use it.  It’s a great day whenever I get to haul my net out of my closet and chase some unlucky insect down.  I’m always a little sad when I fold it back up and hide it back in that corner of the closet.  I swing my net HARD, like a softball bat, so I have to be careful to pay attention to where people are around me when I collect.  But that’s okay.  Unless I’m out collecting with other entomologists, people give me a WIDE berth when I use my net.  It’s obvious from the way they carefully avoid me that most people think no sane adult runs around public parks with a bug net.

Even though I didn’t BUY a net until 2005 I’ve had a net far longer than that.  My first net was a homemade one that I built myself in the 9th grade.  Remember how I mentioned that I did all the girlie 4-H projects in my post about insect cakes?  Well, sewing was one of them.  I made rather non-traditional clothes, but I also put my mad seamstress skills to use in other areas: bug net making!  If there’s anything that makes sewing decidedly ungirlie, I think it’s making nets for catching insects.

My first bug net was a simple contraption I designed that cost less than $2 to make.*  The materials were simple: a wooden dowel, a wire coat hanger, duct tape, a needle and thread, a rubber band, and 1 yard of cheap white nylon netting (tulle – the stuff they use in wedding dresses and other formal women’s attire) from the fabric shop.  Making the net was incredibly easy!  All I did was fold the netting in half the long way and stitched up the side.  I wrapped the rubber band tightly around one end to form a nylon net sack.  I straightened the hook part of the coat hanger and formed the rest into a circle, then duct taped the straightened hook to the dowel tightly so that the circle stuck off the end.  Then it was a simple matter of folding the open edge of the nylon netting sack I’d made over the wire coat hanger and stitching it into place.  Very easy!  My nets took less than 15 minutes to make.

I used these nets for a good 12 years before I finally broke down and bought a professional net.  Why spend $30 on a net when I could spend $2?   I did the entomology project in 4-H for 4 years in high school and used these nets to capture nearly every insect in my collection.  I started teaching other people how to make them.  When my mom moved away and started to look out for insects for me, she made herself a net using my design.  It’s simple, cheap, and it works.  In fact, it was so simple, that I was able to make nets for outreach events on several occasions.  I worked as an intern at my county’s extension office throughout college and we did a lot of day camps and outreach events in the summer.  Because I helped plan, they often had insect themes or activities.  I took huge groups of kids out into Colorado’s high prairie to collect insects using those cheap little nets.  Someone loses one?  Who cares?  One get broken or ripped? Nothing a little duct tape and some thread can’t cure!  I could make enough nets for a whole group of kids for less than $50, which worked perfectly with the small budgets we had for these events, and the kids had a great time collecting.  It made me so happy to put my skills to good use.

Want to know why I eventually bought a professional net rather than continue using my homemade ones?  When I first moved to Arizona for grad school, my car was stolen.  I got it back 5 weeks later, but the thieves had taken everything in my car – my bike, my radio’s faceplate (but not the radio – who DOES that?), and all my bug collecting gear, including my nets.  I didn’t really care that they had taken my bike.  Annoying, but I bought a better one the day my car went missing.  I had to buy a new radio faceplate.  Whatever!  But my bug nets?  That was a major loss!  I was more angry that they’d stolen my bug nets, those stupid little cheap things I made that were completely worthless to anyone but me, than my car.  Those nets and I had some good times and I was sorry to see them go.  I didn’t really have the heart to make more, so I borrowed nets for a while, then finally broke down and bought my own.

That first net purchase led to other net purchases.  I use a soup strainer for most of my aquatic insect collecting, but I bought a good aquatic net eventually.  That’s it up there in the photo.  I bought a few other pro nets that don’t collapse because they’re a little more sturdy.  I’ve made some really fancy nets for aquatic research.  But it doesn’t matter which net I use.  Taking any of them out means I’m going to have a great day, one spent outdoors doing something I love. My nets make me all nostalgic, reminding me of long summers spent working on my insect collection nearly every moment of every day and chasing a western tiger swallowtail for THREE HOURS because I was too stubborn to let it go.  Ah, those were the days!

So here’s to my bug nets!  $2 or $100, my nets have been among my most treasured possessions for years.  I can’t imagine that changing any time soon – and I honestly don’t want it to.  After all, what kind of entomologist would I be without my net?


* If anyone happens to be interested in my net design, I could be persuaded to post a tutorial.  It should be pretty easy to figure out from the description above, but it’s nice to have pictures sometimes.


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Science Sunday: Field Research vs. Lab Research



I really enjoy field work.  Having grown up in an outdoorsy family, I spent a lot of time outside as a kid.  When it came time to choose a senior thesis topic in college, I headed straight for the local wetlands, plopped myself down on a boardwalk, and watched damselflies flying around for several weeks.  I swore to myself that I was going to do all of my graduate research outdoors because that’s what I loved to do.

My regular readers know that plan didn’t quite pan out (click here for examples).  But there’s a reason for that!   There are times when it’s easier do work in the lab and there are questions that are nigh impossible to answer in the field.  So, today I’d like to do something a little different for Science Sunday.  Instead of discussing an article about research, I’m going to discuss a few (very few) of the pros and cons of working in the field versus the lab.  For the scientists out there: you probably know all this already, so thanks for stopping by.  But for those of you who aren’t scientists, this might give you some insight into how scientists plan their experiments and the research decisions they make.

Let’s start with a hypothetical question, something that you might find me doing: do the behaviors of backswimmers (pictured above) allow them to use the air bubble they carry on the underside of their abdomens as physical gills so they can extract oxygen from the water?  Now, there are several different ways I can approach this question, so let’s consider some pros and cons of doing this sort of study in the field.

Field Work

PRO: You are able to observe the bugs in their natural surroundings.

When you’re dealing with behavioral questions, you can often make the best observations in the field.  In our hypothetical scenario, the bugs are going to be much happier, and therefore much more apt to behave as they do normally, if you observe them in the field.  As an observer, you will cause a certain level of distraction that might interfere with their normal behaviors to some extent, but it’s certainly going to be far less than what you’re going to get by scooping the bugs out, driving them back to the lab, and dumping them into containers.  When possible, it’s great to do behavioral studies in the field for this reason.  However, that’s not always possible because…

Con: You have no control over the conditions

To be able to say that X causes Y, you need to do a carefully controlled experiment where all the variables are accounted for.  It’s possible to do experiments in the field, but there are a lot more variables that you have to take into account.  For example, let’s say you’re doing a field experiment with the backswimmers.  However, it turns out that one set of treatments was applied to bugs in the middle of the stream and another to bugs closer to the shore.  If you compare the treatments and observe differences, you can’t ever be completely sure that you know why they’re different.  Your treatments likely had an effect, but what about the differences in flow between the two areas (faster in the middle, slower closer to shore)?  The increased energy demands of swimming in the middle of the stream relative to the areas closer to shore?  The different oxygen levels in the two areas?  Taking your experiment into the lab ensures that the only difference between the two treatments is the treatment itself so you can say that your treatment caused the observed outcome.  You probably also want some field observations when possible so that you provide evidence that your lab experiments didn’t affect the behaviors (e.g. did you know that female mantids don’t normally eat their mates and only do that in the lab?), but this isn’t always possible.

LabLab Work

Working in the lab has benefits, but it’s not always the ideal place to work.  Apart from being able to precisely control your experiments at the cost of removing things from their natural environment, the pros and cons of lab work include:

Pro: Greater access to a wider variety of Research tools and equipment

There are some things that are difficult or impossible to do in the field.  For example, let’s say you want to measure the oxygen in the air bubble that the backswimmer carries with it in the water.  That involves using some expensive precision equipment with specific power and space requirements that are hard to replicate in the field.  You might want to use a microelectrode to measure the oxygen level of the bubble.  Microelectrodes break very easily, so dropping one into the stream or on the ground would be a terrible thing – $5000 down the drain!  You wouldn’t be able to use the stands or the micromanipulators in the field that make using the electrodes easy in the lab.  It’s certainly not ideal to take the computers and analyzers you need to record the data out to the field.  Microelectrode oxygen readings also change depending on the temperature, which is impossible to control in the field.  If you need any sort of fancy equipment, it’s often better to do your experiments in the lab.

Con: Space can be an issue

Working with insects is great because you rarely need a lot space to do your experiments.  For the hypothetical backswimmer scenario, a small lab (heck – a table!) has ample space to do a behavioral study.  But what if you’re working with deer or leopards or bald eagles?  You’re certainly going to have a much harder time bringing them into the lab, nor could you expect their behavior to be normal indoors.  In fact, you’ll probably have to sedate them to get them into the lab in the first place and then house them in small cages while they’re there to do anything with them.  If you’re planning to measure hormones in blood or are interested in body measurements, then this sort of thing is ideal.  If you want to study behavior…  Not so much!  You’ll get better results in the great wide outdoors than you ever will in a lab.

These are the sorts of things all biologists wrestle with when they decide how to answer their research questions.  You have to carefully weigh the pros and cons of any particular experimental design and choose the one that’s most likely to produce reliable results.  Sometimes it’s better to do your work entirely in the field or entirely in the lab, but other studies (like mine!) lend themselves well to doing both.  And thank goodness for that!  I wouldn’t want to spend all my time indoors.  :)


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Friday 5: Caddisfly Case Diversity

Writing my post Monday reminded me of how much I like caddisflies – and how little I write about them here on my blog.  Today I’m going to write about them again.  And because it’s Friday, it’s time for another Friday 5!

Caddisflies are incredibly important aquatic insects for many reasons.  They’re an essential part of many food webs, processing whole leaves into smaller particles that other organisms can consume, breaking down dead material, and acting as a food source for many larger aquatic animals such as fish and frogs.  From a water quality standpoint, they’re sensitive indicators of pollution and valuable when assessing the quality of streams.  They’re also a very diverse group of insects.  In some places you find several different species living together, each building its own style of case and performing various roles within the stream.  In one tiny area of a single stream, you might find big cases and little cases, cases made from leaves or wood or pine needles or rocks, sometimes even snail shells.  The variety can be quite impressive!

To demonstrate this diversity, I’d like to share 5 photos of caddisfly cases from a single river, the Little Colorado River of Arizona’s White Mountains.  These caddisflies were all collected on a single day from a small section of the river near Sheep’s Crossing, a pine wooded area (or at least until the Wallow Fire – not sure what it looks like now!) at fairly high elevation (over 9200 feet).  The water flows fast and cold, though there has been a lot of beaver activity the last few years that’s been transforming the area.  There could be even more – or different – caddisflies there now!

Rock Cases

Many species of caddisfly make cases out of rocks.  This is one example:

Glossosomatid caddisfly

Glossosomatid caddisfly

Glossosomatid caddisflies are known as the saddle case making caddisflies because they make cases that are reminiscent of saddles.  The cases are constructed using silk with rocks attached.  On the top and sides, the caddisfly places large rocks from head to tail.  On the bottom, it uses smaller rocks and makes a much narrower band that wraps under the abdomen.  Think of how a saddle fits on a horse – the mental image is pretty good.  I find these out in the high flow areas of the stream, essentially glued into place on a rock.  Out in this part of the stream they can scrape the delicious algae off the rocks to their heart’s content!  There’s something about this family that I just love and they’ve become my favorite caddisfly group.

Limnephilidae is a very diverse family of caddisflies, but they tend to be rather large and often build their cases from rocks.  An example:

Limnephilid caddisfly pupa

Limnephilid caddisfly pupa

This case is sealed at both ends because the caddisfly has pupated inside.  It will dig its way out of the case when the adult emerges, and then leave the stream to spend its adult life on land.  I usually find these on the bottom of the stream in sandy or gravely areas within a few feet of the banks where they can chew up leaves and break them down into smaller pieces.  Their case is just a tube of silk with moderately sized pebbles attached.  Pretty simple really.  But some cases n this family are much more complex.  Case in point…

Mixed Media Cases

This case is from another limnephilid species:

Limnephilid caddisfly

Limnephilid caddisfly

Rather than using all rocks, these caddisflies build a rock case and then wrap at least the bottom half with leaves.  This is a much more complex case design as the caddisflies have to find both the right size of rocks and stitch them all together, but then they have to find a second completely different material to finish the job.  Pretty cool!  I think these look a little like a sushi handroll.  :)

Wooden Cases

Several species of caddisflies make cases that incorporate pieces of wood.  Some even make cases entirely from wood like this one:

Lepidostomatid caddisfly case

Lepidostomatid caddisfly case

This case is from a caddisfly in the family Lepidostomatidae, a family with only two genera in North America.  I find these larvae, often in very great numbers, near the banks where they break down stream detritus including dead leaves and dead fish.  This species is among nature’s recyclers and plays a very important role in the stream.  The fact that they wander around in fashionable wooden jackets makes them extra awesome.

Vegetable Cases

Many caddisflies make their cases entirely from non-woody plant material.  One example is this brachycentrid larva:

Brachycentrid caddisfly case

Brachycentrid caddisfly case

I just love these little caddisfly neat freaks.  Check out the carefully arranged geometrical case!  Amazing.  If you hold the case with the opening toward you, those little bits of grass form a perfect little square.  These larvae tend to be tucked up in the crevices along the banks where they collect and eat little food particles floating around in the water (diatoms, bits of algae, etc).  I find a lot of them in very small sections of the bank too.  One scoop with my hand dandy soup strainer will often haul up 30 or 40 of these caddisflies!  I usually take two or three and put the rest back.  Otherwise my collection would be overrun with brachycentrids!

There are far more than 5 species in this river, but most of them make cases from these same types of materials because that’s what it available.  If you travel downstream just a mile, the beaver activity is much less and the deeper water flows faster, so you get several other species there, some that build very different cases than any of these.  I think it’s impressive that there are so many varieties of caddisfly in a single mile of river!  This is a seriously diverse group.

So, have I convinced you that caddisflies are amazing yet?  :)


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Well-Nigh Wordless Wednesday: Before and After

I’m doing something a little different today and doing a two for one Well-Night Wordless Wednesday!  I enjoyed posting the photo of the cattle tank last week (I’ve worked in that one – it’s quite mucky), so this week I give you the cattle tank that is my main field site.  This is what it looks like during the spring:

Field Site Before

Field site, before monsoon

And this is what it looks like about two weeks after the monsoon begins:

field site, after monsoon

Field site, after monsoon begins

What a difference a few storms make!


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The Purpose of Caddisfly Case Extensions: A Case Study

Well, Science Sunday ended up getting pushed to Monday, but that’s okay.  It happens!  But today I’m going to share a fascinatingly simple study with you about caddisflies, so I hope it was worth the wait.

I haven’t talked about caddisflies all that much on my blog yet, but I really should.  They are incredibly interesting little insects and hugely diverse as far as aquatic insects go.  Caddisflies fly around on land as adults and look like little bland moths:


Caddisfly adults

Their order name, Trichoptera, means hairy wings, and if you look closely at the wings you’ll understand why: rather than scales, as you see in their close relatives the butterflies and moths, caddisfly wings are covered in hair.  Their common name, caddisfly, is based on a peculiar structure that the aquatic larvae and pupae use, the case.  Not all caddisflies build cases, but those that do build them using silk that they produce and materials they gather from the stream such as algae, pebbles/sand, leaf bits, pine needles, small pieces of wood, etc.  There are a huge variety of cases, many of which are species specific so that you can identify the species based solely on the case.  Others are less distinct, but regardless of the structure of the case, they tend to be big, bulky, heavy things that are much larger than the larvae carrying them.

Over the years, researchers have proposed a variety of purposes for caddisfly cases.  Some are likely helping the caddisfly breathe by stirring the water around the larva, allowing it to collect oxygen from the water via gills that run along the abdomen.  Cases may protect some species from predation as fish and other aquatic predators are less likely to eat something that looks like a pile of rocks or leaves than a soft, squishy insect.  Still other caddisflies may use their cases to weigh them down, causing them to sink to the bottom so that they can move about fast flowing streams with less risk of being swept downstream.  Each species may use its case for a slightly different purpose, or even more than one.

One species of caddisfly, Dicosmoecus  gilvipes, builds a case from silk and plant bits, adding small pebbles as they get older.  The first through fourth instars also attach needles from Douglas fir to their cases (the fifth and last instar does not), attaching them near the top of the case so that they stick far out to either side:

Dicosmoecus gilvipes

Dicosmoecus gilvipes larva. Redrawn from Limm and Power 2011.

This is a rather peculiar arrangement of materials, so researchers Michael Limm and Mary Power wanted to figure out why those fir needle wings were so important.  They considered two hypotheses.  First, the wings might protect the larvae from predation.  Even if the little rocks didn’t discourage fish from eating the larvae, perhaps the pointy spikes sticking off the sides would.  Alternatively, the extensions could help stabilize the larva so that the larva would be less likely to tip over in areas of high flow in a stream.

To test these hypotheses, they did two simple experiments.  In the first, they released caddisfly larvae at the site where a stream flowed into a deep pooled area containing steelhead trout.  One person hid behind a boulder and released the larvae, which were swept into the pool.  A second person observed the fish and counted how many times each larva was approached by the fish, were “mouthed” by the fish, or eaten.  They did three treatments: caddisflies with the case intact, caddisflies with the douglas fir needles clipped off, and naked caddisflies that had been removed from the case prior to release.  In the second experiment, the researchers constructed a large rocking water tank that would roll the larvae over.  They placed a larva on the bottom of the tank and turned the machine on, then counted how many times each larvae rolled before it recovered its footing and how long this took.  They then compared the number of rolls and the time to recovery between caddisflies with cases intact and with the fir needles clipped off.  The team also measured the cases to determine how the width, length, mass, and center of mass changed with the addition of the fir needles.

The reseachers learned that the fir needles increased the width of the case by 410%, the length by 36%, and the weight by 24% and shifted the center of mass upward off the streambed.  They also learned that, while the steelhead readily consumed naked caddisflies, there was no difference in the number of approaches or the number of times the caddisflies were mouthed between the larvae with the extensions and those without.  Clearly the case alone was sufficient to prevent predation regardless of whether the extensions were present or not.

The results of the rocking tank were interesting though.  Larvae with the fir needle extensions rolled three times less than larvae without the extensions.  They also regained their footing more than three times faster with the extensions than without.  The cases might be providing other benefits to the larvae, but Limm and Power concluded that the function of the fir needles is to stabilize the larvae in areas of high flow.  Apparently it’s worth the extra effort of finding the fir needles and carrying around a much more unwieldy case if it means that you are more stable in the stream.

So, why does this matter?  According to calculations the authors did, the drag force required to tip a larva over is more than four times greater when the larva has the extensions than when it does not.  This means that the larvae can safely walk out into areas of the stream with flow up to two times faster without getting tipped over and washed downstream.  The extensions also help the larvae orient themselves so that they’re positioned parallel to the flow.  This decreases the chance of being swept away.  All of these benefits combined likely allow the larvae to wander out into areas of the stream where they would not otherwise be able to go.  Food limits the number of Dicosmoecus  gilvipes that can live in any particular stream, so by increasing their stability by the simple addition of a few Douglas fir needles, the larvae increase the area where they can forage for food in the stream, allowing more individuals to survive in any given area.  Pretty darned cool!

This is yet another example of how an insect can make a very simple, small change that provides huge benefits – just another example of why insects are such amazing creatures!

Literature Cited:

Limm, M., & Power, M. (2011). The caddisfly Dicosmoecus gilvipes: making a case for a functional role Journal of the North American Benthological Society, 30 (2), 485-492 DOI: 10.1899/10-028.1


Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

Science Sunday will be late!

It’s been a busy week and I finally had a chance to spend a little time to do fun things like running errands with my husband yesterday.  As a result, I didn’t finish my blog post and Science Sunday will be late today.  To tide you over until the post goes up (and it’s going to feature a very interesting group of aquatic insects, the caddisflies), I offer this photo of a scene that will soon be making an appearance in Arizona:

Honey bee on palo verde blossoms

Honey bee on palo verde tree blossoms

Check back this evening for the Science Sunday post!


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