Moment

I knew I wasn’t going to get the right photo to fit today’s Photography 101 theme, moments and motion, because I feel like all the photos I’ve taken that have significant moments associated with them have been utterly serendipitous. I had a perfectly mundane day of meetings and e mails today, not the kind of day where I thought I’d come across a “moment” as I like to think of them.  So, I decided to choose an older photo that represented a good moment for me. For those of you who have been reading my blog for a while, you may remember my sharing another photo from this series a few years ago:


I spent a decade studying giant water bugs (and am still studying them, just not full-time anymore). I absolutely love the species depicted here, Lethocerus medius, and they are giant, scary looking insects that lurk underwater.  I spent several summers collecting and working with the eggs. They hatch late at night, however, and since I kept them in the lab rather than at home, I always missed the hatching.

I got this photo when I was visiting a lab in another city to do some research I couldn’t do at my university. I was in the lab something like 16 hours each day and was just getting ready to leave one night when I caught a movement out of the corner of my eye. The tops of the eggs had popped open and the heads of the little bugs inside were visible. I was unbelievably excited – I was going to get to see them hatch! I spent over an hour watching them, taking photos as they progressed. The bugs all hatched at one time, swaying back and forth in unison as they pulled themselves out of their eggshells. I took several videos of their movement, little synchronized rhythmic insectoid waves. I still watch them a couple of times a year and remember.

A short while after I took this photo, it was obvious the bugs were about to come completely free, so I picked up the stick they were attached to. The freshly hatched bugs spilled out into my hands, a hundred or more all at once, and I dashed across the room so they could fall into the pan of water I had waiting. For me, it was a magical moment, little bugs slipping into the water between my fingers, a moment full of movement and life and pure joy, one that to this day I am thankful I was able to bear witness to.

That’s the sort of moment I thought of when I saw the theme “moments and motion,” the sort of moment you don’t expect and instead fall into randomly. My day today was not the sort of day when magical, memorable moments fall into your lap. Those don’t come so often, but I’m always happy to have my camera with me when they do.

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

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Friday 5: Fun Facts About Giant Water Bugs

This week’s Friday 5 features a subject near and dear to my heart: giant water bugs!  If you aren’t familiar with these beasts, they have some really amazing characteristics that make them a fascinating group of insects to study.  I’ve already covered giant water bug parental care and feeding in other posts.  Today I’m going to share 5 fun facts about giant water bugs.  I hope that knowing these facts will help you fall in love with these wonderful bugs!

Lethocerus medius

Lethocerus medius, the biggest giant water bug in Arizona, can reach lengths of nearly 2.5 inches!

1.  The largest true bug (i.e. member of the insect order Hemiptera) in the world is a giant water bug.

Lethocerus maximus is truly a giant, reaching nearly 5 inches in length!  However, if you want to add one to your collection, you’ll have to visit northern South America.  The Lethocerus in the US are piddly in comparison, topping out at about 2.5 inches – half the size of the biggest species.

Abedus cannibalizing eggs

A male Abedus herberti cannibalizing his own offspring after he scraped them off his back.

2.  Giant water bugs can be cannibalistic.

A hungry giant water bug will eat almost anything it can get its claws on, including its own young (only when very hungry or something has gone wrong with the eggs a male is caring for), the young of other individuals, and each other.  Female Lethocerus are also known to rip apart the egg clutches deposited by other females when there aren’t enough males with good egg laying sites to go round.  However, I haven’t observed giant water bugs eating each other in the field unless there is very little other food available and they are getting desperate.  It would seem they prefer not to eat each other, but they will when they have no other choice.

Abedus herberti mating

Abedus herberti mating.

3.  Giant water bug mating can take several hours, especially in the back brooding species.

Mating is a long, involved process in the back brooding giant water bugs.  First the male does little push ups in the water.  These are thought to send vibrations through the water that the females respond to.  After a male and a female find one another, they mate.  Then the female climbs on the back of the male and lays a few eggs, maybe 4.  Then the male shakes her off and they mate again.  Then she lays a few more eggs before being shaken off again.  This goes on and on until most of the back of the male is covered with eggs, sometimes 150 altogether!  You can see how this might take a long time.  The water bugs in the photo took over 6 hours to lay all of their eggs.

Belostoma micantulum

Belostoma micantulum, a giant water bug from Argentina, is one of the smallest giant water bugs in the world.

4.  Not all giant water bugs are giant.

Belostoma parvum, a giant water bug from northern South America, can be less than a centimeter long.  It’s a not-so-giant water bug!  In fact, several species of giant water bugs in the genus Belostoma are actually quite small and don’t live up to the “giant” in their name at all.  The giant water bug pictured here is Belsotoma micantulum, a tiny little giant water bug that maxes out at a little over a half an inch long.  Pretty cute though, especially when munching on a mealworm that is WAY too big for her!  :)

flood

The only flash flood I've ever personally witnessed, though it's hard to see how big this flood was in this photo! Clicking on the photo will take you to a cruddy, low-res video I shot of it and posted on YouTube.

5.  At least one species has a nifty flood-avoidance behavior.  

Imagine you’re an aquatic insect and a flash flood is headed your way.  You’re going to be ground into a bloody pulp if you stick around.  What do you do?  If you’re the giant water bug Abedus herberti, you climb out of the stream before it floods!  This species crawls out of the water and walks perpendicularly to the bank until it reaches shelter away from the stream.  After the flood passes through, it crawls back into the water and carries on with its regular activities.  Awesome behavior!  And you can see a video of it online by visiting Dr. Dave Lytle’s website.  He filmed Abedus herberti leaving the stream after artificially simulating flood conditions with a fire hose.  The video is hilarious, so I encourage you to take 30 seconds out of your day to watch it.

Aren’t giant water bugs cool?  I love my bugs.  Considering they mostly just sit in one place hoping that food will swim by, it never ceases to amaze me just how many wild characteristics these bugs really have.  Hope you enjoyed this little peek into some of the many fascinating things these bugs have going for them!

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

Friday 5: My Favorite Aquatic Bugs

As an aquatic entomologist in Arizona, I come across a ton of aquatic true bugs (order: Hemiptera) as I work.  We have nearly every family of aquatic true bug in the US somewhere in the state and at least one type is found in nearly every water body I’ve encountered.  We have a lot of bugs!  Considering I also study a bug, it seems fitting to devote a Friday 5 to the bugs.  I can’t believe I haven’t done it already!  These are my top 5:

5. GIANT WATER BUGS (FAMILY: BELOSTOMATIDAE)

giant water bug

Giant water bug, Family Belostomatidae, Abedus herberti

Okay, okay.  We all know I love my belostomatids dearly.  They’re awesome though!  They eat things that are vastly bigger than they are, including things with backbones.  Some of them are amazing fliers.  They’ve got some interesting respiratory behaviors (I’m saving that for a future post).  And then there’s the whole parental care thing.  Really, what’s not to love about a giant water bug?  Two more interesting facts: belostomatids are readily eaten in southeastern Asia (a glandular secretion of a Lethocerus species is highly prized in Vietnam) and members of the genus Lethocerus are considered pests of fish hatcheries.  Super cool bugs!

4. CREEPING WATER BUGS (FAMILY: NAUCORIDAE)

creeping water bug

Creeping water bug, Family Naucoridae, Ambrysus sp.

Naucorids, also known as the creeping water bugs, are the often overlooked distant cousins of the water bugs.   As you can see, they look very similar and they are often found side by side with water bugs in streams or ponds.  But naucorids are oh so fabulous!  I am a lover of the unlovable, so I like them partly because they have a nasty bite.  It adds significant zest to the experience of catching them.  I have never been bitten by either water bugs or naucorids, but listening to a person talk about a giant water bug bite and then a naucorid bite, it’s clear that naucorids are vastly more painful even though they’re smaller.  Naucorids are also really cool because they a) use a plastron, a permanent air bubble that allows them to extract oxygen from the water, to breathe as nymphs, b) are sometimes found in hot springs, hot desert pools, or very salty water, and c) can make sounds.  Seriously though: avoid the pointy bits on the head!

3. Toad bugs (Family: Gelastocoridae)

toad bug

Toad bug, Family Gelastocoridae, Gelastocoris sp.

I am absolutely thrilled to come across these little guys!  They’re the most adorable insect on the planet as far as I’m concerned.  Just look at them!  They’re called toad bugs for obvious reasons and they really do look remarkably like some of the little toadlets that crawl up onto the shores during the monsoons.  They also move like toads by making short little hops.  Toad bugs are shore bugs, so they always live near water, but live on land.  They blend in with the shore like mad too.  They’re nearly impossible to see unless you happen to see one jump.  Sometimes I go looking for them, and even then I’ve only seen three or four live toad bugs in the wild.  Toad bugs eat other shore insects and mites and suck water out of the sand on the shores.  Pretty darned cool little bugs.

2. WATER MEASURERS/ MARSH TREADERS (FAMILY: HYDROMETRIDAE)

hydrometrid

Water measurer, Family Hydrometridae, Hydrometra sp. Photo by the fabulous Kate Redmond!

I am totally in love with these bugs!  Like the toad bugs, hydrometrids are nearly impossible to see, even when you’re actively searching for them.  They are about a centimeter long so they’re a decent length, but they are incredibly thin (less than a millimeter wide) and they tend to blend right into the background.  They also move very slowly, so there’s little chance you’re going to catch the movement of one out of the corner of your eye.  Hydrometrids live on the surface of the water in areas where there’s a lot of vegetation and hunt small bugs on the surface.  I think they look a lot like walking sticks, but just look at that fabulous little head!  So cute.  Confession: I once jumped off a boat when I saw one of these on the water’s surface, right out in the open where I actually had some hope of seeing it.  They’re that exciting to find!  (Then just 30 minutes later, my boss and I saw a bear swim across the lake and climb straight up a cliff, and 10 minutes after that were boating through a massive monsoon storm.  Best sampling day ever!)

1. Water scorpions (Family: Nepidae)

Water scorpion

Water scorpion, Family Nepidae, Ranatra quadridentata

I’m going to devote an entire post to these guys, so I’m not going to go into a lot of detail here.  My favorite aquatic bug deserves its own post!  For now, just know that the water scorpions are the most closely related insects to the giant water bugs and are similar to them in many ways.  However, while giant water bugs are the big beefy football captains of the aquatic insect world, the water scorpions (at least the ones in the genus Ranatra, pictured here) are the skinny little nerdy kids that weigh 95 pounds in spite of subsisting on a diet of Coke and chicken strips.  Athletic and muscular versus awkward and gangly.  With a name like water scorpion, you’d think they’d be a little more bad a**, but that is sadly not the case.  Love ’em!

So, are you a bug lover yet?  If you’ve made it this far, it’s probably painfully obvious that I am!  Be sure to check back in a few weeks for more buggy goodness as I attempt to make you fall hopelessly in love with water scorpions!

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

Friday 5: Insect Eggs!

Today’s Friday 5 is going to be shorter and a bit more of a photo album compared to my usual posts.  I work with the eggs of giant water bugs in my research, and if you read my recent post on insect egg anatomy you know there’s a soft spot in my heart for all things insect egg related.  There are some truly beautiful insects eggs out there (if you haven’t seen the National Geographic insect egg article or Martin Oeggerli’s Micronaut website, you should visit both as soon as possible!) and I try to document them when I see them.  Some of the photos are less than perfect, but I take them for myself so I will remember seeing the eggs instead of focusing on producing a perfect image.  Some insect egg photos from my collection:

cactus eggs

Eggs on a barrel cactus spine.

I have no idea what these are, but I wish I did!  The eggs are gorgeous and have some bizarre structures that I would like to look into further.  If you know what these are, I’d love to hear from you!  I found them on a barrel cactus in October.

lacewing egg

Green lacewing egg, hatched.

I actually know what this one is!  Green lacewings lay their eggs on little stalks like these and they’re all over my yard in the summer.  This egg was laid under the porch light where the lacewings like to hang out at night and the larva had already hatched.  I liked the color of the white stalk against the rust colored adobe walls of my duplex, so I snapped a few photos.  Lacking a flash at the time, this was the least blurry.  :)

moth ovipositing on sliding glass door

Moth ovipositing on sliding glass door.

I was sitting on my couch reading one night when I looked up and noticed a moth (likely a noctuid, though honestly I didn’t look that closely) moving around strangely on the sliding glass door to the backyard.  I got up to see what it was doing and noticed it was laying eggs!  I ran to get my obsolete point and shoot digital camera and took the photo from inside the house through the very dirty glass.  This produced a rather cruddy photo.  Still, it makes me smile every time I see it because it was fun to watch the mom laying her eggs on my door.  All of the eggs eventually hatched, so presumably her efforts were worth it!

eggs on strawberry

Eggs on strawberry.

I despise most fruits, but I eat the few I like in massive quantities when they’re in season.  Last summer I was happily working my way through an entire pound of some of the most delicious organic strawberries I’d ever had when I noticed the little cluster of eggs on this berry just before I popped it into my mouth.  Because I’m me, I pondered the beauty of the drab grey eggs against the bright red strawberry for a while and decided it warranted a photograph.  I love how the photo turned out!  I didn’t think to save the eggs to identify them, but I think they’re probably stink bug eggs based on the features I can see in my photos.

Lethocerus eggs hatching

Lethocerus medius eggs hatching

Last but not least, these are some of the eggs I study, laid by the giant water bug Lethocerus medius.  This species is an emergent brooder and lays its eggs above the water line.  The father then carries water to the eggs and protects them until the nymphs hatch.  They are gorgeous, enormous eggs, but they’re even more impressive when they hatch.  The nymphs hatch synchronously, so 200+ little water bugs wriggle their little bodies out the eggs at the same time.  It’s an amazing sight!

I wish more people took a closer look at insect eggs because they are fascinating up close.  There are a ton of different styles and shapes and structures and vary quite a bit from group to group.  They make great photographic subjects too because they don’t move!  I encourage everyone to go out and look for insect eggs around their homes.  And if you get great photos that you’d like to share, feel free to share links on/upload them to The Dragonfly Woman’s Facebook page.  I’d love to see what you find!

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

The Anatomy of Insect Eggs

I work with giant water bugs in my research, but the main focus of my work is actually their eggs.  All the behaviors I observe and the physiology I measure are related to the egg stage of their development.  Today I thought I’d give a crash course in insect egg anatomy using my giant water bugs as models.

But first, a quick disclaimer!  Giant water bugs have strange eggs.  The insect developing inside the eggs require parental care and cannot survive without it in the wild (you can get them to hatch without the parents under certain laboratory conditions) and the exact locations of the structures on the eggs you’ll see here are different from many other insect species.  Still, giant water bugs have the same structures as other insect eggs and those structures do the same things for the insect developing inside the egg as they do in other species.  Just remember that parental care of eggs is rather rare in insects, and the paternal parental care of the giant water bugs barely exists outside their group.

Okay, first things first!  Let’s start with a cluster of eggs:

Abedus herberti

Abedus herberti

Some insects lay their eggs in clusters and others will lay them one by one and really spread them out.  Water bugs lay in clusters so you can see the cluster of eggs where it has been laid: on this male Abedus herberti’s back.

If we zoom in a bit closer, we can start to see what the eggs look like:

Abedus eggs

Abedus herberti eggs, up close!

Abedus herberti eggs happen to change in structure about halfway down, so that’s why you can see the brown change to grey in the photo above.  Some insects do this, others do not.  Regardless, the shell of insect eggs has a special name: the chorion.  Let’s zoom in a bit more and get a good close look at the chorion on the top of the egg:

Abedus egg top

Abedus herberti egg top

This image was taken using a scanning electron microscope (SEM) so that you can get a VERY close look at the structure of the chorion!  This egg was mounted onto an SEM stub upright so that you are looking down at the top of the egg here.  Notice the area indicated by the arrow.  That area is called the micropylar region.  If you look very closely at the image (you can click on it to make it bigger), you can see little white marks within the micropylar area.  Those lines represent the micropyles:

micropyles

The micropyles

Eggshells are meant to contain the animal growing inside them and protect them from the environment.  If anything needs to get into or out of an egg, it has to go through the shell.  That’s where the micropyles come in!  Female insects produce the eggs, but the chorion is deposited before the eggs are fertilized.  Sperm have to get inside the eggs to fertilize them and have to go through the shell to do so.  They enter through the micropyles to pass through the chorion to the egg waiting inside.  The arrow in the photo above shows one micropyle within the micropylar region of Abedus herberti.  There is a second micropyle to the left.  This species has anywhere from 2 to 7 micropyles arranged in an arc, but other insects have different numbers and arrangements of micropyles.

Let’s zoom back out a bit and take a look at the structure of the top of the egg again:

Abedus egg top,showing aeropyles

Abedus herberti egg top

In this image you can see the fine structure of the chorion and see all the little polygons that cover the surface of the egg.  Many insect eggs exhibit raised polygons similar to the ones you see in the Abedus herberti egg.  These are an artifact of the chorion production process in females.  I’m not going into it now because the process by which insects produce eggs is long and involved and better suited to a series of posts (I wrote 19 single spaced pages on this subject as part of the written part of my Ph.D. comprehensive exams!), but those polygons represent the shape of cells that are involved in building the chorion and they’re visible on many insect eggs.

The embryos developing inside the egg need oxygen to survive, but they have to get it from the atmosphere outside the eggshell.  That means the oxygen has to cross the eggshell before the embryos can make use of it.  Sperm enters the egg through micropyles.  Oxygen enters through aeropyles.  The arrow in the image above points to an aeropyle on the chorion of Abedus herberti and you can see several of them dotting the surface of the egg.  I think they look rather like lunar craters!  Let’s take a closer look at an aeropyle:

aeropyles and plastron network

Aeropyles and plastron network

The two holes in the center of the image are aeropyles, little holes in the chorion that allow the embryo inside to get the oxygen it requires.  The exact path oxygen takes from the atmosphere to the developing insect is a little complicated and probably varies from species to species, but the aeropyles are where the path begins.  The number and arrangement of the aeropyles varies across species quite a bit.  Some insects have them distributed across the entire chorion.  Others keep them localized in specific areas (Google “pentatomid eggs” for some good examples).  Many aquatic insect eggs don’t have aeropyles at all and depend on oxygen flowing directly through the shell.  Some aeropyles have sieve-like covers over the opening and others are just big gaping holes like the ones you see in the image above.  There’s a lot of variation, but they all share a common goal: allowing oxygen to enter the egg.

Did you notice that the area within the polygons near the aeropyles looks kinda spongy in the image above?  That’s because the eggs in this species have a structure called a plastron network.  Plastron networks are meshworks made up of many tiny projections of the chorion.  This meshwork is thought to trap air against eggs when they are underwater so that they don’t drown.  Many terrestrial eggs have these plastron networks and this structure may allow them to survive accidental submersion for some time.  Water bugs also usually have plastron networks that may be responsible for their survival while they are underwater.  Lots of other aquatic insects that lay their eggs in water don’t have these structures at all.

The structures I mentioned above are the typical structures you find on most insect eggs.  However, you can find other structures depending on the species.  Giant water bugs absorb water from the environment and the water passes through a structure at the base of the chorion called the hydropyle.  A few other insects have hydropyles.  Other species will have structures to keep their eggs in place once they’ve been laid.  Still others might have horns or other structures that allow them to respire more efficiently.  Just like the animals growing inside them, insect eggs show a lot of variation in color, structure, and arrangement of the structures and can differ a lot from species to species.

I’m still taking entries for my contest for a few more days!  If you want to win the mug, be sure to leave a comment here for your chance.  The winner will be announced Wednesday.

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

Notes from NABS Day 2

meeting logoEvidence for Overland Dispersal in a Flightless Aquatic Insect

Hello again from the NABS/ASLO 2010 meeting!  Today I’m focusing on Day 2 of the conference and my favorite talk of the day.  But first, two things I learned:

— Some aquatic insects are capable of moving a very long distance to get to new or better habitats.
— The person who designed the layout of the Tuesday poster session should be tarred and feathered for coming up with the absolute worst possible layout.  While I feel like my poster went over fairly well (I even had 2 judges tell me that it was very well done , giving me some miniscule glimmer of hope that I might win one of the tiny number of awards at NABS this year), it was a physically miserable experience.  The posters were arranged like this:

poster session

One of the two poster session rooms, the one my poster was in, before the poster session began.

The space was about 8 feet long and about 8 feet wide and each of these little alcoves held 6 posters each.  You could comfortably fit maybe 5 people in this space.  And THIS is what it looked like with 8 people:

poster session

The alcove in which my poster was located during the poster session.

I was forced to stand out in the aisle because I didn’t fit.  Wow that’s bad design!  Still, my scientific experience during the session was great once I got past the bad lighting, the inability of the AC unit to keep up (it was probably 85 or 90 degrees in the room – hotter than outside!), and the cramped quarters.  I got a lot of good feedback.  Considering this poster was the entire reason I came to the meeting, this is a good thing.

But back to my favorite talk of the day.  The title of my Day 2 favorite talk is at the top of the page and is probably easier to understand than yesterday’s if you’re not a scientist.  The talk was given by Kate Boersma, a Ph.D. student in Dr. Dave Lytle’s lab at Oregon State University.  The Lytle lab does some excellent research and Dave has been a star in the aquatics world since he was granted his professorship at OSU, so it’s no surprise that I liked Kate’s talk the best of the ones I heard today.  Plus, she’s a colleague of mine, a fellow giant water bug researcher, so you can’t go wrong.  She works on one of the same water bugs I study, the lovely Abedus herberti:

Abedus herberti mating

Abedus herberti mating.

Kate’s talk was about dispersal of this insect, or the movement from one habitat to another.  But before I get into the presentation, let me say a bit about dispersal in aquatic insects, especially as it pertains to insects in the arid (=dry) southwest.

Aquatic insects living in streams don’t really stay in one place.  They move around a lot, but there is a tendency for them to move downstream.  After all, simply losing your grip on whatever you’re holding onto in the water is enough to sweep you off into the current and far away from your home.  Invertebrates moving downstream by passive means (being swept along by the current), either intentionally or accidentally,  is called invertebrate drift.  Generally, moving downstream is something you want to avoid if you’re an aquatic insect.  Fish eat the insects and other organisms that make up the drift, so there is a high risk of predation for drifting insects.  Streams can also change a lot over their length, so it’s to an aquatic insect’s benefit to stay in the place that is best suited for it.  Insects CAN move upstream though.  They will crawl, or in some cases swim, upstream through the water.  Alternatively, many species with terrestrial adults are known to fly upstream to lay their eggs, thus ensuring that the population at the uppermost portions of a stream (the headwaters) remain stable.  Any movement of an organism from one area to another is called dispersal.

If an area becomes unsuitable for any reason, the insects need to move to another area if they are to survive.  This means dispersing.  This happens frequently in the arid southwest, but how insects move between habitats, the cues they use to signal that a move is necessary, and whether dispersal is limited strictly to up and downstream movements are still poorly understood.  Kate hopes to explain how Abedus herberti chooses to move to a new habitat, how far they can move, and in what direction.  And this brings us to the subject of her talk.

First she described the conditions in the area in which I also do my research.  We have a lot of streams, but many of them are dry most of the year (these are called ephemeral streams because they water only flows for a short time).  Even streams that flow most of the year can mostly dry out during the summer, leaving behind isolated pools of water into which the entire invertebrate population of the stream must go.  As these pools get smaller and smaller, it becomes stressful for the organisms living in them.  Abedus herberti is also flightless, so if the pool dris completely and they can’t find a new source of water, they die.  If they are able to instead move to another habitat nearby by crawling across the land, they might be able to avoid death and prevent the local extinction of populations within the area.  There is some genetic evidence that suggests this is possible, but Kate is the first person to really look into it.

Kate has been interested in which environmental conditions, which cues, prompt A. herberti to move from one habitat in search of a better one.  In her talk, she described a study she did recently.  She expected that pool drying would prompt a water bug to move from one habitat to another, so she set up an experiment.  She set up several opaque tubs filled with water that held smaller tubs inside them.  These inner tubs were assigned one of two treatments: either they were left dry or they were filled with water.  She then placed bugs inside the inner tubs, left them for a period of time (honestly, I didn’t get the time frame down, but it was something on the order of overnight or a week), and then compared the number of bugs that she found in the water-filled outer tubs in each treatment.  She discovered that more bugs moved from a dry tub to the wet outer tub than from a wet tub to the wet outer tub.  This suggests that the insects use pool drying as an excuse to leave the poor quality habitat in search of a better environment.

Kate also presented data on the distance that these bugs are able to move overland, though she did not collect the data herself.  Her labmates collected water bugs from several different pools, marked them, released them back into the pools, and then came back much later and recorded the location of the marked bugs they found.  They discovered that A. herberti prefers to stay in the same area, if not the same pool, in which they were found originally.  However, some had moved.  Of these, the females were found to have moved about 20 meters (just under 65 feet) while the males moved only 12 meters (about 39 feet).  The bugs clearly don’t move very far if they don’t have to.

However, Kate also showed a video that she happened to get through pure serendipity: a rather crispy looking male giant water bug who had left his aquatic habitat, had climbed into a dry streambed, and was hurrying downstream.  This was visual evidence that the bugs are able to move over land if conditions warrant the behavior.  She was also able to calculate a land speed for the bugs of about 4.6 meters (15 feet) per minute.  This is pretty fast for a one inch long animal!  She further calculated the maximum distance the bugs might be able to travel based on some data I had given her regarding they length of time the bugs can remain out of water.  Her calculations suggest that these bugs might be able to move as much as 6624 meters (4.12 miles) before they dry out and die!

So, Kate showed that overland dispersal can occur in Abedus herberti, that they use pool drying as a cue to disperse, and that while the bugs prefer to stay in one place, they occasionally travel across land for some distance in search of a better home.  Pretty neat, eh?  I thought so.  :)

Tune in tomorrow for another edition of Notes from NABS!

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Posts in this series:
Day 0 – Introduction to the Series
Day 1
– Invasive Crayfish
Day 2 – Giant Water Bug Dispersal
Day 3 – Dragonfly Captive Rearing
Day 4 – Integrating Service-Learning Programs into College Courses
Day 5 – Impact of a Small Preserve on Stream Health

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

Giant Water Bugs Eating

I didn’t post anything last week because I was in the midst of chaos with family and friends, making final preparations for my wedding last weekend.  But now I’m back at the computer and getting things done!  Since I just took a short break, I thought I’d take this opportunity to express my thanks to everyone who’s been keeping up with my blog.  I appreciate your comments and your support!  It’s gratifying to know that something I enjoy doing so much is informative and helpful to others.

Lethocerus indicus eating a small fish

Lethocerus indicus eating a small fish

Today I thought I’d post a short video that illustrates how giant water bugs eat.  Giant water bugs are fierce predators and are known for being able to take down very large prey such as snakes, fish, turtles, and even birds!  Even more amazing is that they accomplish these feats while they barely move at all!  Giant water bugs are called sit and wait predators.  If you think about that phrase for a moment, the behavior it describes should become obvious: giant water bugs sit in one place and wait for prey to swim by.  As much as I love giant water bugs and try to get people excited about them, I’m the first to admit that they sit in one place for long periods of time without moving at all.  In fact, they can even be a bit boring to watch at times.

Abedus herberti

A giant water bug in the pose they normally adopt while waiting for food to swim by.

However, any boredom instantly disappears if the giant water bug you’re watching encounters food!  Part of what makes them exciting to watch is their structure.  I wrote about how to tell the American giant water bug genera apart several months ago and talked about the raptorial forelegs that giant water bugs possess.  Most of the time, you’ll see giant water bugs sitting underwater, holding onto a rock, the bottom of the pond or stream, or a piece of vegetation with only their hind two pairs of legs.  The front legs, those strong raptorial forelegs, are held in front of them, as in the photo above.  If food swims by, they thrust those muscular forelegs forward very rapidly, fold the legs over the food, and then retract their legs back toward their bodies, bringing the prey close to their heads.

The giant water bug then begins to eat its food.  First, it has to find a place it can insert its piercing-sucking mouthparts, that beak that you can see hanging off the front of the head of the bug in the image above.  It will probe the prey item with its beak until it finds a soft place into which it can insert its mouthparts.  The water bug then injects the prey with chemicals that break the tissues down, turning them into a sort of soup.  Finally, the bug sucks the liquid out of the prey and into its own body.  This part is rather like what you do when you take a drink or eat a smoothie with a straw!

Depending on the size of the prey item, the eating part of the process can take a very long time, up to 10-12 hours.  It takes a long time to inject all those chemicals and suck up the resulting soup.  But the prey grabbing happens VERY fast!  So fast that most prey items probably don’t even see the bug before it’s too late.  And so fast that the very first time I fed a bug as a graduate student, I dropped the forceps in which I held the prey (a mealworm) and jerked my hand out of the way as hard as I could.  There may or may not have also been a loud girlie shriek involved, one that I may or may not have been very happy that no one else was in the lab at the time to witness.  :)

So, to get an idea of just how fast water bugs are when they grab food, I recorded my lab bugs the last time I fed them.  Without further ado, I give you a giant water bug (species: Abedus herberti) eating a mealworm!  Pay special attention to how fast the bug grabs the mealworm.  If you look closely, you can also see it probing the mealworm with its beak!  Look for the probing in the space between its eyes and its left foreleg:

Pretty cool eh?  That speed and power in their forelegs allow giant water bugs to catch and eat some very large things.  How amazing is it that an insect, and an aquatic insect at that, can capture and consume a bird?!  And I’m not talking about little birds either.  There is a published report of one taking down a woodpecker.  Now that’s just impressive.

I should be back to my usual posting schedule now, so look for a new post next week!  I’ll be installing an educational aquatic insect pond at the Biosphere II soon, so I’ll be posting about that for sure.  But first, another quick video, this time of a non-insect aquatic invertebrate: the flatworm!

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