Sandy plants: a paper, an update, some wacky plant photos.

A little while back, I published a paper that Rick and I had been working on for awhile. In short, there are quite a number of plants which entrap substrate - sand, dirt, etc. - on their surfaces with sticky trichomes. These species occur worldwide in dunes, beaches and deserts. Quite a number of people, dating back to the late 1800's, had hypothesized that this "sand armor" must protect the plant, but nobody had actually gone out and tested it. So we tested both the hypothesis that it is physically defensive (who wants to chew on sand?) and that it is a form of camouflage (since of course, it makes the plant look like the background).

Abronia pogonantha, one of the sandiest plants I've seen. Photo: EL.

We found support for the physical defense hypothesis (in two tests) and did not find any evidence that the camouflage protects the plant. You can read (Inkfish - one of the best science blogs) or hear (Quirks and Quarks) more about this project.

The best part of publishing this was hearing from a prominent researcher (who had noticed this phenomenon), that he tells his students: "if you don't believe that sand is defensive for the plant - try sandpaper instead of toilet paper!" Since publishing this, I've been able to continue this research and observe quite a few more cool sandy plants - some of which were new to me and some of which I had only heard of.

The best sandy plant in the world. The common names for Pholisma arenarium include "scaly-stemmed sand plant", which is my personal favorite plant name ever. About an inch tall. Near Morro Bay, CA. Photo: EL

In that paper, there is a list of sand-entrapping plants. Many of these I had seen and noticed. Others were from published literature. I surveyed a bunch of really good naturalists and they suggested many others (their list was the longest). That is how I happened upon Pholisma, pictured above. This odd plant is a borage (the family includes some wellish-known plants including borage, heliotrope, fiddleneck, baby blue eyes, phacelia, etc.). Looking like a lump - maybe a mushroom? - it is completely chlorophyll-free, instead sucking nutrients from nearby plants (it is an obligate parasite, like Indian pipe, Monotropa, in the east). And the coolest part, of course, is how much sand it catches - it is nearly completely covered! It is very possible that plants which coat themselves in sand suffer a photosynthetic cost because less light reaches them. For Pholisma, that doesn't matter at all!

LOOK AT ALL THAT SAND! (I am pretty sure those purple things are flower buds - I didn't unfortunately get to see a flowering individual).

Pholisma was, since I learned about it last year, the top of my list of must-see plants and seeing it was one of my spring highlights so far. I happened upon it accidentally while looking at another sand-entrapping plant, Abronia umbellata (I used Abronia latifolia in my experiments).

Abronia umbellata is not as sandy as some congeners, but it is pinker than most! (there is also a really, really, cool paper on floral evolution in this species - check it out). Photo: EL.

The central coast of California has three species of Abronia which grow in close proximity on coastal dunes. Abronia maritima is generally on the beach while latifolia and umbellata are a little farther up (and occasionally grow over each other). They each catch sand to some extent.

Abronia maritima. The yellow anthers are positioned right above the stigma and seem to drop pollen onto it (from my couple flower dissections). It has far smaller flowers than the other species. I'd bet quite a bit that it is selfing. Photo: EL. 

Abronia latifolia, the common sand verbena for most of the California coast. Common doesn't mean boring though, its quite awesome. Photo: EL

My labmate/collaborator, Patrick, found this bizarre plant. My best guess - and it was pre-fruiting, so I can't be sure - is that its an umbella x latifolia hybrid. It had leaves reminiscent of latifolia (large, broad, very fleshy but held upright like umbellata and somewhat in between the two in glandularity) and stems which were stickier than umbellata, but very red like umbellata. The flowers were too long for an abberant maritima (and leaf structure wrong), but seemed fine for either latifolia or umbellata (though with aberrant coloration). Jury is out. Thoughts? Photo: EL

Abronia are awesome (everyone knows that already) but there are some smaller, more inconspicuous plants that are also really good at sand-catching.

This is Tiquilia plicata. It mostly grows as a little roadside weed in the Mojave. It catches lots of sand on the margins of its leaves (!) and stems. Margins of leaves are usually where caterpillars and other chewing insects begin feeding... (hand-wavy adaptationist explanation over). Like Pholisma, it is also in the borage family. Photo: EL 

Tiquilia has nice flowers, but you have to look really hard to find them (they are tiny). This was a tall individual growing in a less-sandy spot (hence the lack of sand on the leaves and stems in the photo - the bottom still had lots). Photo: EL. 

Another new favorite plant was Centrostegia thurberi. A tiny, cherry red, spiny bizarre thing, it is mildly sticky and has bracts encircling its stems which catch lots of sand - seemingly with stickiness and also just being shaped like a bowl. This was another favorite. 

Centrostegia thurberi. Photo: EL.

It catches a lot of sand on its stems, but... (photo: EL)

It also does this! Dipsacus - teasel - often has these sorts of bracts that fill with water and mosquito larvae and stuff. I've never seen bracts full of sand before (and every plant had them!). Photo: EL. 

And lest I turn completely into a botanist, there were some insects, too. Importantly, there was one caterpillar - Hyles lineata - that was really common in a bunch of spots on Abronia. This species, the white-lined sphinx moth, is common over much of North America some years and absent others. Fortunately for me and unfortunately for many herbaceous plants, it is having a good year in southern California (especially near Anza Borrego).

This Abronia villosa is not as happy as I am about this big (3"+) final-instar caterpillar. Photo: EL. 

While Hyles likes to eat Abronia (I've found them on pogonantha, latifolia, umbellata and villosa this year), they not like to eat sand at all. While it doesn't have a good mechanism for taking it off, it seems to concentrate on nonsandy plants first and then on nonsandy parts of the plant, but it always ends up eating the sandy parts of the plant eventually.

A green-morph H. lineata on pogonantha. They come in lots of colors - black, green, yellow and all manner of in-betweens. They all seem to turn into identical moths. Photo: EL

Unsurprisingly as they don't like it, sand on plants is damaging to them. A normal Hyles mandible at pupation looks like this:

An SEM micrograph of the right mandible of a Hyles lineata fed on nonsandy Abronia latifolia. Those "teeth" are for grinding up the plant before it enters the body. Photo: EL

But if they eat sandy plants, they get pretty rough:

Look at the "teeth" - or lack thereof - on this right mandible, from a caterpillar feeding on sandy A. latifolia. Photo: EL

That's it for today: a description of a study, some weird sandy plants, and a teaser of a future paper...

The woolly bear presidential election outlook, 2016

In the age of cell phones, accurate polling of the electorate has become difficult. In a world where a disproportionate percentage of people answering landlines for pollsters is white and over 50, we desperately need a new method of predicting elections. As the 2016 presidential election looms, a crack team of UC Davis innovators has a promising new source of information, woolly bear caterpillars (Platyprepia virginalis).

A woolly bear contemplates the madness of the 2016 election cycle while resting on its preferred host plant, a coastal lupine. Photo: Eric LoPresti

Rick Karban, a UC Davis professor of entomology, has tracked woolly bear caterpillar abundance since the early 1980’s at Bodega Bay, California. Each March, Karban censuses the same patches of lupine that he has for over 30 years. The study asks a vexing question: Why are there are so many caterpillars in some years and so few in others? Many insects, including pests cycle like this, therefore it is of keen interest to many. Dozens of papers later, Karban, his students, and his collaborators have answered a great many questions, including how caterpillars deal with parasites, whether population cycles are influenced by rain, whether caterpillars enjoy eating plant hairs, and how caterpillars avoid their predators.

The population highs and lows seem random at a first pass, a jagged line moving up and down each year. 

The collected data, 1983-2015, full data available here. 

What separates high years from low years? These motivated researchers have found a striking pattern in this data. This data set includes eight presidential election years, with four Democrat and four Republican victories. Plotted with colors corresponding to the party association of the winner, the pattern becomes obvious.

Red corresponds to Republican presidential victories and blue to Democrats. To reiterate: this is actual data!

Woolly bears have years of high abundance when Democrats win and low when Republicans win. The average woolly bear abundance was 0.21 (+ 0.07 se) woolly bears per lupine in Republican years and 1.96 (+0.27 se) in Democratic years.  This data shows that woolly bear abundance in March is a good predictor of presidential victories in the general election.

It is tempting to assume that woolly bears are Democrats (and were particularly thrilled by second-term Bill Clinton), but we cannot exclude the possibility that their abundance is a protest gesture. 

Note that 2016 is not included on the preceding two graphs. For about a year, news sources have made predictions about the primary race and have even speculated about the general election. Given their wildly erroneous predictions thus far for both primaries, trusting their predictions for the general election seems ill-advised. The woolly bears, on the other hand, have a 100% accurate prediction record over the past 30 years. In years of low abundance, a Republican is elected, and in years of high abundance, a Democrat. 

Therefore, we are pleased to announce the woolly bears’ prediction. In mid-March of this year, Karban censused the woolly bears for their opinion on this volatile election year where no subject seems out of bounds and the populist wings of each party have come out like no election in recent memory. Even the woolly bears seem hesitant this year. 

Full data, including this year's census (conducted in March).

A superficial examination suggests that 2016 will be a Republican year – woolly bear abundance is not particularly high. However, looking a little closer, it may not be. The number of woolly bears per lupine bush in 2016 (0.53) is higher than the average Republican year by 152% and is 36% above the highest Republican year ever recorded (1988). However, it is only 27% of an average Democratic year and still only 36% of the lowest Democratic year (2008). This result is without presidential precedent in the last 30 years.

We suspect that the Republicans have the edge. However, a valid hypothesis would be a third-party winner, such as a right-leaning independent (a logical placeholder in between Democrats and Republicans). Perhaps Donald Trump will take particular interest in our data. Alternately, a contested Republican convention could produce a fractured party and the old Republican woolly bear average would not accurately represent the mean caterpillar abundances seen by this new party.

The mainstream media have been shockingly inaccurate in their predictions so far, even despite complex and supposedly accurate statistical models. We need a new strategy to predict key events such as the 2016 presidential election. Rather than trust the opinion of a few people with a pulpit, the historically robust predictions of this population of caterpillars may serve as a better guide.

A congregation of woolly bears meets on a lupine flower spike, presumably to discuss politics. Photo: Eric LoPresti

(This research has been in progress and was presented at ESA 2014)

This post was written by Eric LoPresti, Mikaela Huntzinger, Patrick Grof-Tisza, Ian Pearse, and, of course, Rick Karban (who we suspect is not fooling these infallible caterpillars with his Bernie Sanders impersonation). 

Rick Karban/Bernie Sanders. Who is who? Photo on left stolen from Berniesanders.com, right: Mikaela Huntzinger.

Data I'll never publish: Antirrhinum herbivory

Inspired by this post, I'm going to try to put the results of small (but interesting) experiments up here every once and awhile. In the summer of 2014, I spent a lot of time washing plants. I was - and still am - curious of the function(s) of plant exudates. I primarily did this with Trichostema laxum and Atriplex rosea (in 2013), but I also did it with Mimulus layneae and Antirrhinum cornutum (California snapdragon). The snapdragon gave me interesting results.

(this post should also be regarded as potential project for someone else: I started it in May - there is plenty of time to get up to McLaughlin and do it again this year).

One of the experimental A. cornutum, showing leaf damage. 

This snapdragon, while not as heavily glandular as Trichostema or that Mimulus, is fairly glandular-sticky, even entrapping a small number of minute insects (see the table/supplementary material). Under the microscope, you can see the fairly dense short glandular trichomes (the longer trichomes are mostly nonglandular) on the stalk and flower bud.

Stem of A cornutum with an entrapped insect.

Flower bud showing short glandular and long nonglandular trichomes.

Wondering whether the glandular exudate is defensive, I did an experiment where I removed it with water. Most glandular exudates in CA summer annuals seem water soluble, so a spray bottle rainfall takes off much of the exudate (observationally verified in situ with a 20x loupe - plus whatever was in this exudate made suds on the plant!). This manipulation was my first treatment group. Of course, adding water to a plant has an effect of its own, so I also had a water control group, where I added the same amount of water below the plant's leaves, as to not wash off any exudates. Finally, I had a true control group, which received no water whatsoever. I instituted these treatments on the 30th of May and reapplied them on the 17th of June. Each time, I recorded the number of leaves, flowers, fruit, and plant height, as well as any damage. I also checked the plants, but did not reapply treatments on the 2nd and 19th of July (the last check all were senescent).

During the experiment, plants suffered two main forms of herbivory. The first type, which was most common and most destructive, was that the stems were entirely clipped off. I'm nearly positive this was by jackrabbits (indicated by a single flat cut diagonally across the stem) and it usually killed the plant. The photos below shows what remained.

A killed experimental A. cornutum plant. See it?!? Its the little stem to the bottom left of the flag. Also notice a nice healthy Lessingia in the background. They, too, are extremely glandular and sticky.  

A survivor of mammalian herbivory. If the meristem was not completely destroyed, they often came back and branched like this. Like the classic overcompensation "herbivore-plant mutualisms", the resulting plants were often bigger than the others, with more reproductive structures, but unlike this "mutualism", it was too late in the season and they had low fitness, as they could not mature these structures. 

The mammalian herbivory was not random. Of the 25 plants per treatment, 11 in the control group, 13 in the rainfall simulation (exudate removal) and a whopping 20 in the water control group were eaten by mammals (this is nonlethal, lethally was 10, 12, 18). With a simple chi-squared test, we can demonstrate that this was likely nonrandom (X2 = 7.3688, df =2, p = 0.025) (for lethal, X2 = 5.5714, df=2, p = 0.062). Why were the mammals targetting the water control plants so heavily?

Were they bigger and thus easier to find or just more profitable to eat? They were not significantly different in height, fruit or flower numbers from the other two groups during any check. I don't have data on plant quality (perhaps the less water-limited plants were more nutritious or something?).

The other type of damage was equally-interesting. Heliothis phloxiphaga is a generalist caterpillar on glandular plants. It was the primary herbivore on my columbines, as well as a common herbivore on Trichostema laxum and other sticky plants. Like most heliothiine noctuids, it feeds primarily (but not exclusively) on reproductive structures. I only observed it once on Antirrhinum (eating a fruit), but all the fruit damage I found was consistent with it (and that's one more time than I saw a jackrabbit eat it!).

The other type of damage: caterpillar fruit predation. 

I had hypothesized, that if the exudate were defensive, the washed plants would be most heavily eaten. This hypothesis was supported with the fruit damage. Rainfall plants received far more damage than the other groups. (note: I didn't actually analyze this with zero-inflated binomial, as it should be. There is a problem, in that only 7/25 of the water control plants had any fruit at all because of the rabbits.)

A crumby excel graph of proportion fruits damaged.

What does this all mean? Obviously, it means that mammalian and insect herbivores are responding to different plant traits. What they are exactly, I'm not sure (especially for mammals). If anyone (nudge, nudge, wink, wink) were to repeat this experiment, with a larger sample size, and maybe some other mechanistic experiments (perhaps cage controls and lots more trait data to see what is different in the water control and rainfall manip groups), I think its a pretty good system that someone could get a paper - if not a few - out of.

Cheap and unstealable bicycle taillight instructions

This is the first non-ecology/evolution post on this blog, but bike safety is another important subject in the world and one of very few that I feel qualified to write about publicly. Because you want every chance against the moron driver reading his/her cell phone and not paying attention to the road around his/her four-ton SUV, it is important to be visible. Reflectors are necessary, but having a taillight in addition is always a good idea.

(EDIT/UPDATE, 12/2016 - I switched from using the cheaper lights shown in the pictures here - to using 5050 lights, which are a quite a bit brighter. I think the added brightness is worth it, and they aren't much more expensive. I don't know what it does to battery life. - I've also switched from hot glue to heat shrink tubing, but hot glue is still cheaper and more people have a hot glue gun than a heat gun)

In Davis, and likely elsewhere, head- and taillights are stolen constantly and decent ones are expensive (>$20). I suspect those two reasons are why so many folks in Davis don't have taillights (don't get me started on helmets!).

A cheap - ~ $2 taillight. Brighter than many on the market, weatherproof, long-lasting...

Building a cheap taillight that isn't likely to get stolen is fairly easy - and as a bonus, this is brighter than most of the more expensive ones! Here's a quick run-through of the materials and how to do it. It took me less than 10 minutes, even while taking these photos.

Really all you need is a 9V battery terminal, 2 sections of red LED and ~6 inches of two colors of wire.

Materials (in two parts):

Things you already have:

Hot glue gun/glue
Soldering iron/solder
Electrical tape
Zip ties
Wire (I used 22 gauge)

Things you may need to buy:

9V battery terminal (2.99 for 5 at RadioShack, WAY cheaper online in bulk - free if you take it out of some old piece of electronics!)
Red outdoor LED strip lights (this is the kicker - its about $10 for 5 meters - you'll need about 4" - but useful for all sorts of projects or you could make ~90 sets of tail lights).

The Royce Union's seat stays. Note already flaking paint - not going to screw anything up here. 

Plug in your soldering iron and hot glue gun.

Next, place your battery terminal under the seat, the LEDs where you want them, and cut 4 pieces of wire to reach between the two. then strip each wire - on one side strip about 3mm and the other about 8 mm. Strip the ends of the battery wires about 8 mm if they need it, too.

Now cut a section of LED at the cut points (noted on the strip, on mine, these are every 3 lights). Cut the terminals out of the plastic on the LEDs.

Decide which color wire is going to be hot (+) and ground (-). This is important in LEDs unlike normal light bulbs. Twist the two hot wires (8mm stripped end) together with the red wire leading from the terminal. Do the same with the black wire and other two.

Soldered connections. Yellow is my "hot" wire, blue my ground. 

Time to do some really easy soldering. place your soldering iron on one side of the twisted together connection - wait for it to heat up and draw solder through the other side to get a good solid connection (see above).

LEDs with solder on the copper contact points.

Now get a drop of solder on the copper contacts on each LED (see picture above). Place the tip of your soldering iron on the copper and the tip of your solder a hair away also on the copper - let the copper heat up and draw the solder instead of melting the solder directly on the iron.

Solder drawn through the 3mm stripped ends. 

Then draw solder into the wires on each of the 4 on the 3 mm stripped end. Now look for + and - signs on the LED contacts and line up your wires. The soldering here is easy - without using any solder, press your presoldered wire onto the top of the little solder bubble on the correct contact. With a little pressure, the solder from the contact and the wire will melt together and you will get a good contact (see below).

Good connections to the LEDs. 

Now test your connections - gently tug them (don't PULL) and then put the battery in.

Good connections. Make sure not to cross your two soldered connections, as it looks like is occuring here (though it actually isn't). 

Cut off a little bit of e-tape and wrap each of the 2 to 1 wire connections. Use your hot glue gun and place a nice bead of glue over the just soldered LEDs - this will waterproof that connection (which would short with just a little water). Make sure the hot glue goes over any exposed wire or copper contact on the LEDs.

Waterproofed!

Now mount it up to the bike. This will depend on your set-up. I used zip-ties and super glue - I wasn't worried about ruining the paint on this older, cheaper, beat up bike. If you are, use double-sided tape or zip tie the LED strip on. The adhesive backing on the LEDs themselves are junk - you'll have to do something else. I mounted the 9V under the seat, where it is unobtrusive and less likely to get really wet.

Mounted and working! Note the battery zip tied to the seat rail. Make sure your seat is in good position if you do that. 

My back of the envelope calculations for battery life expect about 10 hours with a GOOD QUALITY 9V battery and the LED draw that was on the packaging (not sure whether that is correct). Don't buy batteries at the dollar store. Also note - most LED strips, including the one I used, run brightest at 12V (and are "rated" at 12V). On my other bike, I run the longer strips off a 6V battery (and have 2' of wire, which allows voltage drop) and red works fine, however, it won't run clear or green. Red is the least sensitive to low voltage and it draws the least (good for battery life!).

(UPDATE: that same battery is going strong 11 months later. I commute on this bike often, though I didn't for about 5 months of the field season. I don't know how many hours I have over the 11 months, but I'll bet its well over 10!).

Now you can use the rest of the LED strip for other projects...

Late 1950's Huffy Daisy Daisy tandem, with green "ground effects". Currently powered off a 12V motorcycle battery (would probably last a year on it!), but I'll get a rechargable 12V pack for it eventually (still working out the kinks of the bike - it was in many boxes when I bought it a couple months ago). 

Mark and recapture project for students!

I've had the pleasure of teaching many groups children from preschool to high school age during the last decade or so in a variety of settings: camps, classrooms, field trips and informal natural history discoveries on the sidewalk (just recently jumping galls in the Central Valley here).

One activity that I have done a few times, and particularly enjoyed, was doing a mark and recapture study on dragonflies with elementary/middle school students. In my opinion, it is a pretty perfect project - you get to teach the scientific method, a little bit of math, and a good bit of natural history. I didn't come up with this project (I think Taylor Yeager, of Mass Audubon, suggested doing it with grasshoppers, initially - but that was the summer of 2006 or 2007, so my memory is a bit hazy) but I've run it a few times with kids from ~9 years old to high school age.

Hetaerina americana, the American rubyspot, my favorite odonate in California. A damselfly, these are just as suitable for the study described here, though a little more fragile. 

The goal of the project is simply to estimate the number of dragonflies in a given area such as a large field or a pond. You could easily adapt this to grasshoppers, milkweed beetles or any other larger invertebrate that can be easily handled and marked (bumblebees or butterflies might not be as good). Mark and recapture is a standard technique used in wildlife studies and the basic idea of it is very simple - you mark a known number of animals, then you go back and capture a bunch and see what proportion of that sample was marked. Obviously, in real-world applications, the math is much more complicated, but for our purposes, if we mark ten bugs the first day and capture 10 the second day, two of which are marked, we have a population size of 50.

You'll almost certainly see Pantala flavescens, the world's most widespread dragonfly. Catching them is a bit harder - they fly high and fast! This is a female. 

Dragonflies are supremely suited to this activity however. They are often abundant, easy to handle and mark, children generally have no aversion to them and they are just challenging enough to catch to occupy students for hours (and to get lots of energy out while running around the field with nets!).

Rhionaeschna sp. Chiloe Island, Chile. WHO DOESN'T LOVE DRAGONFLIES?!?

Of course, the first thing you should do is to get all the students to guess the number of dragonflies in that area. They generally have no idea; guesses vary by orders of magnitude (from 10 to 1 million!). Then it is just a matter of giving everyone nets, teaching them to safely handle dragonflies and going out and catching 'em. We've used normal sharpies and put a dark band on both forewings of the individuals we captured as a mark. For easier record-keeping, we set up a station in the center with the sharpies. I found with younger students, it was easier (and safer for the insect) if I took it out of the net and marked it (those being the two steps where wings are easily shredded or broken), then let the students identify and measure it. Taking dragonflies out of nets isn't hard - put your pointer and middle fingers on opposite sides of their body and gently move their wings up so that you have all four together and remove from net. Even 12 year-olds can remove and mark with proper instruction. Most dragons will need a few seconds to pump haemolymph back into their wings after this process; you can place the dragonfly on the catcher's nose - this is especially entertaining for all others involved!

An Aeshna/Rhionaeschna sp. This is the proper way to hold dragonflies; using two fingers, pinch the four wings together gently. To mark it with sharpie, it helps to put the wings flat on a clipboard and gently put a small mark. This is a female - note the lack of a bulge on the bottom of the first couple abdominal segements (compare to photos below). 

The other way to hold dragonflies is to firmly grip the upper segments of their legs (I usually try to hold two - though I am holding only one in this photo) between thumb and forefinger. This allows viewing of the wing pattern and veination, but is trickier and requires some practice to not rip off legs and let the dragonfly get away. They can also bite you in this grip, not a problem for little ones, but big Aeshnids can draw blood!

With high school groups, I've taught them how to sex the dragonflies and then made comparisons of male and female sizes and sex ratios. This is an interesting activity, as in upland areas, most caught are females and near water bodies, most are males (you can count on this result with all but a few uncommon species). The reason is that males of most species patrol territories near prime egg-laying spots and catch the females and mate with them immediately prior to egg laying. Females, being harassed constantly near water, generally forage in areas farther away. This is especially pronounced in Enallagma damselflies - the bright blue males may be found by the hundreds at any pond, but its really hard to find the duller females nearby - sex rations on a local scale may be 100:1 or more!

Blue dasher, Pachydiplax longipennis, one of the most abundant dragonflies in the US. Note the water mites on its abdomen - these have really interesting natural histories (too long to describe here, but look them up). Also, note the bulge on the lower side of the first couple abdominal segments - this is a male (compare above). 

The next day, we go back out and catch them again - to avoid double counting individuals, we use a second color sharpie on these. Then we conclude by doing the calculation of total population size, figuring out who was closest (the most exciting part for the students) and discussing the drawbacks. The students have always come up with good hypotheses for why the estimate might not be accurate (there were too many high-flying dragonflies, one day was cloudy, etc.) and it generally provides good fodder for a short and informative discussion. With older students, summary statistics on sex ratio, the body size measurements and population sizes of each species can be done and discussed.

The only individuals we don't mark are tenerals - these are just emerged and they have not fully dried their wings and marking would almost certainly hurt them). Note the glistening wings and really pale body. In another day or two, this Sympetrum sp. will be cherry red!

No dragonfly post would be complete without this monster. Arguably the world's largest dragonfly, Phenes raptor lives in bogs in Patagonian Chile and Argentina and has somewhat terrestrial nymphs, an oddity for an odonate. Males also have the coolest set of abdominal claspers (those projections at the tip of the abdomen) of any of the hundreds of species I've seen! 

The eyes of emeralds, family Corduliidae, lend them that common name. 

What you'll need (not very much!):

1) Nets - 1 per student is ideal, but partners are fine, too. Wooden-handled aerial nets are not expensive (<$10) and will last a long time and take a good bit of abuse.
2) Sharpies
3) A good field guide. I use Dennis Paulson's excellent guides for the US, though there are really good regional ones, like Blair Nikula's Massachusetts guides and others. Identifying dragonflies and damselflies in all but a few genera (Sympetrum, Enallagma) is really simple and can be done by most high school age children with pretty good accuracy.
4) Clipboard, data sheets.
5) Two days of predicted sunny weather!

You could have students make nets. During a trip to Peru, my net was stolen within a week. I bought some mosquito netting, bailing wire and made this net for <$1. It lasted me the whole season without issue - several of the dragonflies on this page were caught with it. 

Do give this a try next year if you have students for a couple days! Let me know if you do, I'd love to hear how it goes.

Another interesting thing to note - and could be measured by the students - is the size of the wings (length, width). This dragonfly, Pantala flavescens, has HUGE wings for its size. Unsurprisingly this species is probably the most migratory and best dispersing insect - of any group - on earth. You can find this species near you - pretty much nomatter where you live!

A meadowhawk (Sympetrum sp.) like above. This is a male - told by the bulge in the abdominal segments as well as its red color (females of this genus are yellowish).