Friday 5 (on Saturday): Capturing Insect Behaviors

A few days ago, the place where I work started a new weekly activity, a nature story time for young children.  After reading a story about butterflies, the leader took everyone up to our native plant garden to look at some live butterflies.  They were totally upstaged by a black rat snake sitting curled up in the wisteria vine, but there was a good crowd wandering around looking at things.  At one point, my boss called me over to look at something, a group of insects flying over the grass.  I told him what I thought they were, but I didn’t give it much thought as I needed to get my volunteers ready to do the weekly ladybug sampling.  I was about to go into the office yesterday morning when something flew by that reminded me of that little swarm of insects and how interesting it was.  So, I took my camera down to see if I could film it and was happy to walk away with a short recording.  Later in the day, I ended up with some time to kill after work and before my evening moth program, so I headed back down to the garden to take some photos.  I ended up with several videos of fun insect behaviors, so I thought I’d share some with you!  First up, the little swarm…

Swarm of Scoliids

Scoliids are awesome wasps!  They’re gorgeous creatures with bold markings and you can find them by the dozens at flowers in my area of North Carolina. Now I’m not entirely sure what the scoliids in the video (Scolia dubia) are doing, but there are two good possibilities.  Scoliids are parasites of scarab beetles, including the green June beetles we have in very great abundance around here. That area where they were swarming is also an area where the beetles have been very active until recently.  The wasps could have swarmed the area because there were a lot of good beetle larvae to parasitize by laying their eggs on them!  The other option: males are known to do little mating dances for females, a wiggly little S shape or figure 8s.  You can see these sorts of patterns in the video, and I know at least some members of the swarm were males, so it could have been a bunch of males showing off their sexy dances for females.  Either way, it was super cool to see so many scoliids flying around in one area!

Munching Pipevine

The woolly pipevine is currently COVERED with pipevine swallowtail caterpillars!  I’ve shared some photos of their awesome defense mechanism before, but the video above highlights their feeding behavior.  I don’t care as much about how it looks as how it sounds.  If you can’t hear it, turn the volume up. You can hear those little buggers chewing!  You can stand 5 feet back from the vine and hear these little popping noises and it’s all the caterpillars crunching up pipevine leaves.  I think it’s fantastic!

Off to Pupate

Once the voracious little pipevine swallowtail caterpillars have eaten enough to grow to a certain size, they wander off to pupate away from the vine.  The video above shows a caterpillar wandering.  That little guy was surprisingly fast!  Desperate to pupate?

Courting

There have been a lot of butterflies around recently as they’re getting a late start on their summer activities.  I came across the scene above in the native plant garden, a male and female variegated fritillary getting ready to get it on.  Bug porn!  The pair ended up being scared away by a bird or something that flew overhead, so I only got the courtship, not the result…

And last, but not least:

Gulf Fritillary Nectaring

Apparently these butterflies are exciting here!  Considering I’ve only been here two summers and I’ve seen them both summers, they didn’t seem that exciting to me, but I was talking to one of the leaders of the annual Wake County Butterfly Count today and he told me he’s only seen them in any sort of abundance only three years out of the 50 or so years he’s been watching butterflies.  Perhaps their movement into North Carolina is due to climate change?  Or perhaps the warm winter we had?  Who knows, but they’re beautiful so I can’t say I’m sorry they’re here.

Because I’m getting this up on Saturday and not Friday, I think it’s only fair to share a bonus video with you!  This isn’t an insect behavior, but one that I think is really entertaining:

For whatever reason, the juvenile hawks seem to LOVE the wind turbine!  You’ll see them up there riding around like this every now and again.  It makes me smile every time I see it.

I have had a great bug weekend and have more to look forward to tomorrow, so my weekend’s been going great so far.  Hope you all are having excellent weekends as well!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Friday 5: SciOnline Art Show Entries

If you follow me on Facebook, you may have seen my note earlier this week mentioning that I’d submitted photos for consideration for inclusion in the Science OnlineScience Art show (because I’m attending SciOnline next week – woooooooo!!!!), all photos that depict insect behaviors.  You’ve seen several of these before, but I’m going to present them all here together, and tell you a little bit about the behaviors that they represent.  I only included one terrestrial insect in the bunch:

Leave Me Alone

Pipevine swallowtail caterpillar, Battis philenor

Pipevine swallowtail caterpillar, Battis philenor

I’ve posted this one before, but this is the larva of the pipevine swallowtail, Battis philenor, a huge and beautiful swallowtail butterfly that feeds on (wait for it!) pipevine plants as a larva.  I poked this caterpillar just before I snapped this shot so that the yellow bits above its head would become visible.  Those little horns are the osmeteria, little knobs coated in stinky fluids that some caterpillars use to deter predators.  They’re spectacular in this species!  You can’t beat that yellow against the purple-black larva.

The rest of my entries were aquatic insects.  First up, another shot I’ve posted before:

Giant Water Bugs Hatching

Giant water bug, Lethocerus medius

Giant water bug, Lethocerus medius

This species of giant water bug, Lethocerus medius, tends to hatch at night so until the evening of this hatch, I hadn’t ever actually seen the process.  I was in the lab working on some research close to midnight when I looked over and saw all the “lids” of the eggs I was working with pop up – all at one time.  The bugs spent the next 45 minutes or so wiggling out of the eggs, doing everything in near synchrony.  Shortly after I snapped this shot, the bugs all tipped forward and row after row of tiny, new giant water bugs suddenly dropped into my hands, and then into the water.  It was one of the most wonderful things I’ve ever experienced – and I’m so happy I had my camera handy so I could document it!

SCUBA Beetle

Predaceous diving beetle, Thermonectus nigrofasciatus

Predaceous diving beetle, Thermonectus nigrofasciatus

This is one of my favorite aquatic beetles, the predaceous diving beetle Thermonectus nigrofasciatus.  It’s an awesome beetle for many reasons, but I like it in part because it uses a sort of SCUBA tank approach for breathing underwater.  The beetle swims to the surface (and these are powerful, graceful swimmers, unlike my next few entries!) and gathers an air bubble that it stores under its wings.  Then the beetle can swim around underwater, sit at the bottom and relax, eat, find mates – anything! – while breathing the oxygen in the bubble.  Once the air runs out, it needs to return to the surface to get more.  This big, beautiful girl was resting after an energetic swim about the container.  The sort of shimmery sheen on her body is a thin coating of air that surrounds most of her body.  Isn’t she beautiful?!  (And if you want to know how I know this is a girl, I direct you to my post Aquatic Insects that Suck for more information.)

Next, another aquatic beetle:

Snorkeling Beetle

Predaceous diving beetle larva

Predaceous diving beetle larva

This beetle is another predaceous diving beetle, just a little younger than the one pictured above, and a different species.  Like the adult beetles, the larvae live in water and rely on air from the surface.  However, the larvae don’t carry air around with them underwater.  Instead, they stick the long rearmost segment of the abdomen out of the water, allowing air to flow into the larva’s respiratory system.  It works rather like a person using a snorkel!  The larva can “hold its breath” for some time underwater as well, but now and again it will stick that tail up so it can gather some more air at the surface.  Super cool behavior!

And because it’s what I work on most, I give you a giant water bug breathing:

Breathe In, Breathe Out

Giant water bug, Abedus herberti

Giant water bug, Abedus herberti

I wrote a whole post on how this species breathes, so I’m not going to go into a lot of detail.  This giant water bug (Abedus herberti) is, however, rather similar to the adult beetle pictured above in that these bugs carry air under their wings and need to return to the surface periodically to renew it.  Like the adult beetle, this bug is able to extend the length of time they can remain underwater by taking advantage of a neat trick of physics with another behavior, but I’ll refer you to the longer post if you’d like to read more about it.

So those are my entries.  They’re not all perfect photos, but I chose them because they depict the kind of behavioral entomology that I do rather than their photographic merit.  I also think some of these photos represent behaviors that few other people have documented photographically.  I have no idea whether any of my submissions will be chosen for the final show, but I hope at least a few cool insect behaviors will be featured among all the other fantastic art that is submitted to this show.  And even if they’re not, I suspect I’m going to have a wildly good time at Science Online next week!  I’ll likely be tweeting and blogging (right here!) and giving updates on Facebook next Wednesday – Saturday.  Feel free to follow me online if you’re interested in hearing about the things I’ve learned about science communication online.  I couldn’t be more excited!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Friday 5: Insects Behaviors I Observed At the Park

I went to a local park with my husband late yesterday afternoon.  He’s continuing to recover from his surgery and is becoming more and more active, so he wandered around the park listening to a podcast while I took some photos.  While we were there, I observed several insects flying about in the warm air.  Today I’m going to share five behaviors I saw during the 30 minutes we spent along the pond at the park!

WARNING: I didn’t think to check my camera settings before I started shooting today, so I took all of my shots at 1600 ISO.  My camera starts to get noticeable grain at 400 ISO, so today’s photos are going to be, well, rather cruddy.  Won’t be making the mistake of forgetting to check the ISO setting again though!

Damselfly Seeking Shelter From the Wind

Damselfly on lee side

Damselfly on lee side. It's halfway up that yellowy-brown cattail leaf, in case you're not finding it. Told you the photos from today were awful!

Yesterday was rather windy.  Damselflies don’t fly well in strong winds and I’ve observed them doing one thing over and over again in high wind conditions like I saw yesterday: they fly around to the sheltered side of the vegetation rather than continuing to fly in the wind.  Perhaps they’re moving to the sheltered side hoping to wait out the wind or maybe they’re just optimizing their hunting by finding a place they can fly reasonably well – I don’t know.  But, they seem to either hunker down in the vegetation or move around to the lee side and continue on with their business.  Considering my interest in odonate responses to changes in weather, I find this behavior fascinating!

Dragonfly Patrolling

patroller

Patroller, that blur indicated by the arrow.

I only saw a handful of dragonflies (probably due to the wind), but there was one impressively large darner (blue-eyed darner I think, though it was quite far away) flying back and forth along the stream between the spring outfall and the pond.  It flew by several times as I watched, mostly in the shade of the palm trees.  It was definitely doing some hunting because I saw it chase several small flies up into the “beards” of the palm trees, as is sort of evident from the photo above.  Wow do the darners fly well!  It’s always a treat for me to watch them!

Fly Mating Swarm

Several insects are known to form mating swarms.  Often they’re made up of male insects swirling about in a column in the air, competing for the best position.  When a female flies into the swarm, several males will try to grab her first, but only one will be successful.  I was at the park just before the photographic magic hour, so it was very apparent that there was some serious fly nookie happening at the pond!  With the great backlighting I saw several mating swarms around the park: over the water, over the grass, over the trees.  I couldn’t even begin to tell you what kinds of flies they were (best description I can give is “small!”), but they were fun to watch.

Ants Foraging

Pogos on Bread

Pogos on bread

I came across the scene above directly across the path from the sign telling people not to feed the wildlife, to resist the urge to feed bread to the ducks.  Apparently someone wasn’t paying attention!  But these ants seemed quite thrilled with their bready windfall and kept swarming over it.  There were little bite marks all along the crust!  I believe these are Pogonomyrmex harvester ants, though the photo is WAY too grainy to use to get a better ID from anyone.  You’ll just have to trust that I know at least a few ant genera.  :)

Butterflies Puddling

Puddling blue

Puddling blue

I’ve written briefly about butterfly puddling before, but I am always thrilled when I see it in action!  Today’s puddlers were lycaenid butterflies, the delicate little blue butterflies that are common in many areas.  Though it looks like the butterfly is on dry sand in the photo, it was actually quite damp – and salty too I’m sure!  Butterflies often puddle (i.e., suck liquid out of dirt or from shallow puddles) to get the salt they need in their diets.  It’s always nice to know that beautiful, flimsy little butterflies are potentially sucking up the salt from dog urine.  (Or maybe I’m the only one that thinks that the gross things butterflies make them infinitely more appealing!)

It’s not really within the realm of entomology, but there was some interesting fish nesting behaviors happening at the pond today too.  Several fish had these little round depressions in the pond bed that they were guarding from the other fish.  Really fun to watch, so I feel I should mention it too.  All in all, another fun day of wildlife sighting (if not a great day for photography)!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Science Sunday: Dragonfly Accompanying Behavior

Happy new year everyone!  This year New Year’s Day also happens to be Science Sunday, so I’m going to start 2012 off with a science filled post.  Woo, science!  :)

Every now and then, I’ll get an e mail from someone during the dragonfly swarming season telling me a story of how the writer walked outside and had a dozen or so dragonflies follow him/her closely as he/she walked.  Most of the people who have this experience think it’s rather magical, but it’s unexpected and they want to know what’s going on.  Happily, this behavior has actually been covered in the scientific literature!  So, I’m going to start the new year by discussing a paper that deals with this interesting behavior that was released in the odonate science journal Odonatologica in 2010, authored by O and J Holusa of the Czech Republic.

For those if you who have followed my Dragonfly Swarm Project, you know that dragonflies often swarm because there are a lot of small prey insects in the area that attract them, forming a sort of all-you-can-eat buffet for lots of hungry dragonflies.  In essence, the dragonflies are taking advantage of abundant food that is easy to capture.  Swarms just happen to form if there is enough food for several dragonflies to eat.

A similar behavior called accompanying has been documented by a few odonate researchers.  It works like this.  When a large, slow-moving animal such as a hippo, rhino, or human walks through an area, two things happen.  Insects that are attracted to the animal, such as blood sucking insects, follow them as they move.  Other insects, those found on the grass, brush, or ground, also move out of the way by flying, jumping, or running.  Small clouds of flying insects therefore form around the large animal as it moves.  If you’re a dragonfly, these little clouds of insects are a great source of food.  And, if you are a dragonfly that lives in an area where there are few bushes and flying insects are unlikely to move around much during the day, accompanying large, slow-moving animals means that you’re more likely to catch a tasty snack than if you wait for the little insects to fly on their own.

Brachythemis leucosticta

Brachythemis leucosticta. Photo licensed under Creative Commons by F. Lo Valvo and is available at http://en.wikipedia.org/wiki/File:Libellula.jpg.

One species of dragonfly, Brachythemis leucosticta, has been well documented performing this accompanying behavior, following large mammals within its African range.  It tends to live in open, sparsely vegetated areas where movements of large animals could improve prey capture rates.  The Holusas were curious whether the European populations of B. leucosticta would exhibit the same pattern of behavior.  They also wished to document how far the dragonflies would accompany a large mammal and whether males or females were more likely to take part in the behavior.

They performed their very simple experiment with a population of B. leucosticta along the River Barbate in southern Spain.  They started in the area where the dragonflies perched in the shade near the water and walked perpendicularly away from the shore. When dragonflies followed them, they counted the number of individuals, determined the sex of the followers, and recorded the distance at which each dragonfly returned to its perch.  The researchers walked to the end of the floodplain and then made a wide arc back to the starting point, repeating the walk many more times over a two-day period.

With this experiment, the authors learned that dragonflies would usually follow them away from the water, flying close to the ground in front of them.  Fewer than 5 dragonflies would usually follow the researchers, but they recorded one group of 11.  Females were more likely to accompany than males, making up approximately 67% of the total observations.  Females also accompanied further than males (up to 111m in famales and 89m in males), though both sexes typically returned to their perches before the researchers had traveled 40m from the water.  Finally, of the 53 walks where dragonflies accompanied, dragonflies were observed catching and eating prey in only 3.

The authors made a few conclusions.  First, they noted that though the prey capture rate of accompanying dragonflies was rather low, less than 2%, this was probably a higher prey capture rate than they would experience without accompanying.  They also pointed out that few insects flew out of the grass as the researchers walked and the dragonflies captured prey every time small flying insects were observed.  Accompanying is therefore likely a valuable means of capturing prey in a habitat that is rather inhospitable for small flying insects.

The authors also attempted to explain the differences in accompanying distances they observed between males and females.  They suggest that because the females are lighter colored than males, they are not as noticable to the prey and are more successful at capturing prey via accompanying and therefore persist longer.  They also suggest that because the males are darker, they heat up more quickly upon leaving the shade.  I personally think this is highly unlikely, so I’d like to add a third possibility: that males return to their perches sooner becuase they are territorial and might lose their territory to other males if they stray too far.  Because females are not territorial, they can afford to accompany large animals further from the water to take advantage of the flying insect bounty.

Now, this behavior has not been confirmed in any US dragonfly species, but it is suspected in three: the green darner, wandering glider, and black saddlebags.  All three are commonly reported in static and migratory dragonfly swarms in the US, so these are dragonflies that are flying during the dragonfly swarming season.  This is also the time of year that those e mails start to come in from people asking why dragonflies are stalking them.  I think there’s a connection: the dragonflies in a swarming area are very likely accompanying people, forming little groups around people kicking up little flying insects as they walk.

Tomorrow I’m going to talk about another curious behavior that I haven’t been able to find any information about, but has been reported to me three times now.  It’s a bizarre behavior, so I hope you’ll check back!

Literature Cited:

O. Holusa and J. Holusa (2010). “Accompanying” behaviour of Brachythemis leucosticta (Burmeister) in Europe (Anisoptera: Libellulidae) Odonatologica, 39 (1), 63-70

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

Well-Nigh Wordless Wednesday: Puddler

I love it when I walk out my front door and see this sort of thing going on in the parking lot:

puddling butterfly

Giant swallowtail puddling

The irrigation system in my housing complex breaks all the time, so we end up with little puddles all over the parking lot that attract butterflies.  Butterflies, such as this giant swallowtail, have a hard time getting enough salt and minerals in their diets, so they “puddle” – they suck up moisture from damp areas rich in the nutrients they need.  Apparently we have a salty parking lot because butterflies LOVE it!  And I love photographing them, so I consider it a win-win situation.

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

Friday 5: Leafcutter Bee Nest Caps

The bee house I put up in my yard in mid-April has been a complete success!  Nearly every cavity has been filled with nesting materials and eggs and now I’m waiting for the new bees to emerge.  I’ve watched them obsessively and am keeping hard-core notes about the whole process, so I am totally in love with my bees!  One thing that has fascinated me is the variety in the capping stuctures and materials used among cavities.  To the best of my knowledge, all of my bees are these:

bee

A leafcutter bee (Megachile) bee making a nest

They’re a species of leafcutter bee in the genus Megachile.  Even though they’re apparently all the same species, they’re still building their nests according to… something!  Maybe it’s individual preferences or access to the building materials that controls it, but three different caps might be built by three different bees on the same day.  Fascinating!  My bees have been spending 2-3 days busily building their nests and laying eggs and then spend part of a day building a cap to seal everything safely inside.  They’ve made 5 different types of caps so far, perfect for Friday 5!

Resin Caps

resin cap

Resin caps

The first several bees made these caps.  Then they stopped making them.  Most recently, bees have been STEALING the resin from the completed resin caps, cutting pieces away from the caps and hauling them off, and then recapping the nests with mud.  Odd!  I assume there’s a resin shortage now and they’re scrambling to find it wherever they can.  When the bees build this kind of cap, they bring big globs of it from somewhere on the other side of my house, then stretch it across the opening.  (The bee in the photo at the top has a big glob of it in her jaws, ready to stick it onto the cap.)  Then they pile a bunch more on the front, making a thick, flexible cap.  They smell awesome too!  You can smell the resin from several feet away.  Reminds me of vacations in the pine topped mountains in Colorado…

Leaf Caps

Chewed leaf cap

Leaf cap, in progress. (This one is still green, even though it's now dry.)

Some of the caps, though not many, are made of chewed leaf bits.  The bees bring in large pieces of leaves or flower petals or other plant materials, then chew them up and stick them onto the nest.  Presumably they are sticking the leaf fragments together with saliva.  The best thing about the leaf caps is the variation in color!  Most of them are green like this one, but I have one yellow, one purple, and one vivid red one too.  Awesome!

Rock Caps

Rock cap

Rock cap

These seem to be the least popular choice, but there are a few.  The bees use resin to attach little pebbles (which they collect from the corner of my yard) onto the front of their nests.  After they build up a few layers of rocks, they call it good and either start a new nest in another hole or fly away.  I love watching the bees make these caps!  There’s something about a bee flying around with a rock nearly the size of her head clamped in her mouth that is both inspiring and terribly entertaining.

Flat Mud Caps

Flat mud cap

Flat mud cap

The mud caps are very popular with the bees in my bee house and they take one of two forms.  The flat mud caps are built so that the outer edge is flush with the face of the log in which the cavity is located.  After they dry a bit, they tend to sink inward in the middle a little, giving them a gentle concave look.  To the best of my knowledge, the bees are making the mud themselves by carrying little piles of dirt from another part of my yard, mixing it with saliva and chewed leaf bits, and then spreading the whole mess across the nest entrances.

Round Mud Caps

Round mud cap

Round mud cap

This was the last style of cap to appear in my bee house, but they look really fabulous!  The round mud caps are a sort of mixture of the flat mud cap and the rocks cap.  The bees stick a bunch of little rocks onto the front of the nest, building out past the edge of the log.  Then they plaster over the whole thing with mud as in the flat mud cap.  The result is a cap that extends well beyond the nest entrance, almost like the little developing bees inside are blowing bubbles in the mud!

Watching my bees has been great and I’m very pleased my bee house has worked as well as it has.  And just look at all the individual choices being made by the bees!  Fabulous.  I’m definitely going to make myself some new bee houses (even bought a new power tool – my first circular saw – to do it!) because it’s been great fun watching them build their nests.  I highly recommend the experience!

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I am going to do my best to get a blog post up on Monday, but there’s a good chance it won’t happen.  I am leaving town for a family emergency today and that is a lot more important than getting a blog post out on time.  I will be back, and as soon as I can, but if you don’t hear from me for a while that’s why.

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Hellgrammites

We had an insect trading session in the class I’m TAing this semester, so everyone brought in extra insects they had in their collections to trade for things they didn’t have.  I’m going to discuss some of my observations about the trading session in an upcoming post (I was fascinated!) but today I’m g0ing to focus on the specimen I was most excited about: a live hellgrammite.

Hellgrammites are the larvae of the insect known as the dobsonfly and they are fabulous (or at least I think so).  In their adult form, dobsonflies are pretty gnarly looking.  Males tend to have long, intimidating mouthparts:

Dobsonfly male

Dobsonfly male. Awesome photo by Jessica Lawrence, available at http://bugguide.net/node/view/ 419853/bgimage

Though the mouthparts look scary, they’re really pretty wimpy.  The males of most species can only inflict a minor pinch because the mouthparts are so large they can’t get any leverage on them.  But these giant mouthparts do have a purpose – and, as in most cases where insects have supersized body parts, it all comes down to sex.  Female dobsonflies size up potential mates according to the size of his mouthparts, and in the world of the dobsonfly, bigger is definitely better!  The males with the biggest mouthparts are the sexiest, most desirable males, so some dobsonflies have evolved truly massive ones.

So a male with giant mouthparts mates with a female with more reasonably sized mouthparts to produce eggs.  Those eggs then hatch and these crawl out:

Hellgrammite (Corydalus cornutus)

Hellgrammite!

Now I love hellgrammites and find them completely fascinating.  I am always thrilled to find these in the streams I work in and I can spend hours watching them.  Even so, I’ll be the first to admit that these are some truly vile looking larvae.  They’ve got big, strong mandibles they use to rip apart their prey and they are formidable predators.  They’ve got a pair of hooks on each of two fleshy prolegs on the back end (more about these in a moment) that stick to your fingers or clothes like burrs.  They’re big larvae too.  The hellgrammite in the photo is nearly 3 inches long!  And then there are the long, spindly gills sticking off the sides of the abdomen that give them an alien look.  These do nothing to diminish their threatening appearance and I think it makes them look like big, aquatic centipedes.

But those hooks and gills are also part of why I love hellgrammites.  If you’ve kept up with my blog, you know that my research broadly involves respiratory behaviors of aquatic insects.  Judging from the adaptations hellgrammites display and the habitats they live in, they need a lot of oxygen to survive.  That’s where the hooks and the gills come in: they both help the hellgrammite get as much oxygen from the water as possible.

Let’s consider the hooks for a moment.  If you’re an aquatic animal that requires a lot of oxygen, there is a specific type of water that is best suited to your needs: cold, turbulent, fast flowing streams or rivers.  That’s exactly where you’ll find hellgrammites, clinging to rocks right out in the areas of the strongest flow in cool or cold streams.  However, a giant three-inch long larva, even a flat one like a hellgrammite, is going to have a hard time holding onto the rocks when there’s water slamming into it constantly.  So, they’ve got these:

hellgrammite hooks

Prolegs and paired hooks at the posterior end of a hellgrammite.

Those little hooks grab a hold of the rock so that they aren’t ripped off the substrate and washed downstream.  Hellgrammites are also usually found under big rocks in these fast flowing streams, so the currents they experience are weaker than those on the upper surface of the rock.  Those little hooks aren’t always enough to keep a large hellgrammite in place if they venture out onto the top of the rock.

Hellgrammites are highly adapted for collecting oxygen from the water as well.  If you recall from my post on aquatic insect respiration, insects living in turbulent, cold water maximize their opportunities to collect oxygen from the water.  If they expand their exoskeleton into gills, their surface area increases and they can absorb as much of that relatively abundant oxygen as possible.  Hellgrammites have a lot of extra surface area in their gills.  The feathery looking gills sticking off the sides are rather immobile and simply increase the surface area.  The other set of gills, the puffy dandelion fluff looking ones, have muscles attached to them.  When a hellgrammite become oxygen stressed, it can wave those gills around through the water:

Waving the gills around is a form of ventilation and allows the hellgrammite to extract as much oxygen from the water as possible, especially under less than ideal situations.  The gill movements stir the water around the hellgrammite, pushing deoxygenated water away from the body and bringing oxygen-rich water into contact with the gills so that it may be absorbed.  Behavioral ventilation of this sort is common in aquatic insects and gill movements like this have been recorded in several species, especially within the mayflies.  Still, I can’t help but marvel at just how beautiful the hellgrammite gill movements are!  I hadn’t ever seen this behavior before I noticed it in the insect trading session and I was amazed.  I found it shocking that something that ugly could also have such a stunning characteristic.  It was almost hypnotic watching the hellgrammite pulsing its gills and I could have watched it for hours.

But then I was snapped right out of my gill-inspired reverie when the hellgrammite started to swim around the jar:

I don’t know about anyone else, but I find this sort of abdomen flicking, backwards swimming kinda creepy.  Crayfish do it too and it’s just bizarre.  Doesn’t that look like rather inefficient way to maneuver around your environment?  I can’t easily come up with a reason why this sort of swimming would have developed, though I’m sure there’s a good explanation.

Yep.  Hellgrammites are appalling to look at, but they are amazing in so many ways that I have to love them anyway!  I hope I’ve given you at least a little taste of my appreciation for these monsters of streams and rivers.  I’ll probably describe my plan for making a horror movie called “Hellgrammite!” at some point in the future.  I am sure you are all eagerly looking forward to hearing all about it.  It’s going to be fantastic!  :)

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