Tag Archives: crab spider

Photo of the Week – September 16, 2011

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Sometimes I’m amazed that there are any pollinators left in the world.  Not only do they have to survive habitat loss, habitat fragmentation, herbicides/pesticides, introduced diseases, and competition from introduced pollinators like European honey bees, pollinators also have to deal with all the various predators that wait in ambush on flowers!  Imagine making your way through a deadly obstacle course all day long, finally arriving home, opening the refrigerator to grab some dinner, and getting eaten by a troll hiding inside.

In December of last year, I wrote about crab spiders and their tactics for capturing visitors to flowers.  The photo below is of an ambush bug that uses eerily similar tactics.  You know, just to keep those bees on their toes.

Ambush bug (Phymata sp.) on stiff sunflower (Helianthus pauciflorus). Beatrice, Nebraska.

Ambush bugs are closely related to assassin bugs, but have thicker bodies and legs.  They are well camouflaged and sit on flowers, waiting for something to get close enough to grab.  Once they have prey in their mantis-like front pincer legs, they (like crab spiders and assassin bugs) inject the with paralyzing and liquefying saliva and then suck the insides right out of the poor visitor.  I find it fascinating that two creatures as distantly related as crab spiders and ambush bugs have such similar hunting and feeding techniques.  Assassin bugs and ambush bugs both use piercing mouthparts to inject their saliva and suck out the bug innards, while crab spiders have fangs.  Otherwise, the story works about the same way.  I doubt the prey have a preference one way or the other…

This particular ambush bug was sitting on a stiff sunflower in a prairie planting on the campus of Southeast Community College in Beatrice, Nebraska a couple weeks ago.  It sat very still for the 5 minutes or so it took to get these photos.  The challenge wasn’t to get the insect to stop moving – it was to wait for the tall flower to stop swaying in the breeze!

For more information on ambush and assassin bugs, you might be interested to read this article from the Missouri Conservationist.

Coneflower Surprise

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Last Friday, I was at my in-laws’ farm in eastern Nebraska (Sarpy County).  Toward evening, the hot, sunny, windy day transformed into a cloudy evening with light winds.  I stepped outside to look over the little patch of restored (reconstructed) prairie in their front yard.  The sun was going down behind the clouds, but there was a small gap of clear sky between the clouds and the horizon.  Foreseeing a small window of time with some good photography light, I went back to the house and grabbed my camera and tripod.

As I came back out of the house, the sun was just coming out from beneath the cloud bank.  There were only a few places in the little prairie that were being hit by the low-angled light, and the best color in the prairie seemed to be the gray-headed coneflowers that were just starting to bloom.

Gray-headed coneflower (Ratibida pinnata). Reconstructed prairie in Sarpy County, Nebraska.

I chose a flower and set up the tripod to photograph it.  After only a couple of shots, a stink bug flew in and landed on the flower.  Just as I began focusing on the stink bug to see if he’d pose for me, a crab spider suddenly squirted out from inside the canopy of coneflower petals and grabbed the startled stinkbug.

A fuzzy first attempt to photograph the stink bug immediately after it landed.

Initially, it looked like the spider was having a hard time finding a place to bite the stink bug through its tough carapace, and for a minute or so, the bug was pulling the spider around the flower and it looked like an even chance that it would escape.  However, the spider eventually latched onto the bug near its rear end and hung on tight.  The stink bug continued to crawl around the flower, hauling its spider cargo with it, but over the next few minutes, the pauses between movements became longer and longer.

The stink bug pulled the tenacious spider around the flower, but the spider hung on tight.

In this photos, you can better see where the spider sunk its fangs into the bug (soft underbelly?) Eventually, the stink bug stopped moving altogether, and it was game over.

As the sun went completely below the horizon, the stink bug finally stopped moving altogether.  After a few more minutes, the crab spider let go and rotated the bug into a new position within its grasp – apparently to feed?  I’ve watched crab spiders attack and feed quite a few times before, but don’t remember seeing one changes positions to feed – they usually seem to just feed through the same initial fang holes they make to kill their prey.

A few minutes after the stink bug gave up the ghost, the spider flipped it around in its grasp. This photo was taken several minutes after the sun had gone down.

Right after the above photo was taken, the wind kicked up, and it felt like a storm was coming, so I left the spider to its meal and went inside – feeling grateful for the opportunity I’d just been given.  Who needs TV??

Photography Notes

For those of you who are photographers, you might be interested in a couple things about this photo series.  As I said earlier, the sun was low in the sky.  It was a nice red color, providing great warm light on the flowers and bugs.  However, the light intensity was low, and there was a slight breeze that was moving all the plants back and forth a little.  I set my camera’s ISO on 500 to allow me to take the photos at between 1/25 and 1/50 of a second, which was sufficient to stop the motion.  The trickiest part was timing the shot between wind gusts so that the eyes of the stink bug were in focus (or, a few times, the eyes of the spider).  I shot about 50 photos over 10 minutes or so, and about 15 turned out sharp.

The last photo above was the trickiest because the sun had been down for a few minutes, and there was no direct light at all.  It was too dark to stop the wind-driven motion of the flower, so my only chance at getting the last shot – which was too good to miss – was to use flash.  Unfortunately, I don’t own a flash other than the pop-up flash on my Nikon 300s camera.  So, I popped up the flash and set the camera on Program.  Having tried to use the flash for macrophotography before, I knew that the flash alone was too bright for close-up shots, so I improvised.  I pulled my arm out of one sleeve of my t-shirt and wrapped the shirt sleeve over the flash and then took the shot.  The shirt acted to diffuse the flash’s light but still allowed enough light for the photo to work.  It took a couple tries to get the focus right (the stupid flower kept moving!) but it eventually worked.  I’d never tried this little trick before, but now I might have to throw an old t-shirt into my camera bag for similar future emergencies!  (or maybe just the sleeve…)