Crab Spider – Master of Deceit

This Crab Spider on the Arctic Primrose is not holding its paralyzed prey with its legs, but rather with its jaws.

A most unusual and astonishing comment occurred many years ago when I was part of a public study session on snakes. Randy Grimes, snake expert from Neenah, was just finishing the three-hour workshop in which he displayed and discussed several species of snakes, including the King, Western Fox, Bull, Yellow Rat, Garter, Indigo, Anaconda, Timber Rattlesnake and a huge Burmese Python.

Quite a few members of the audience, young and old, took great pleasure in handling most of them, particularly the huge Indigo and the Burmese Python. Suddenly from out of the blue came the question, “Randy, do you like all creatures in nature as much as you like snakes?” His answer, which greatly amused most of us, was, “Well, one thing I really don’t like are spiders!”

Actually there are relatively few people who are willing to tolerate snakes or spiders, largely attributed to misunderstanding and ignorance of both kinds of animals. Another point to be considered is the element of surprise. Usually we encounter them when we least expect to and become startled and even frightened. Movies and even old wives’ tales have done little to educate humans as to the great value and general harmlessness of both creatures.

This past May 19 two friends, Beth and Don, along with Charlotte and me, were doing some exploring along the rocky shore of south Toft Point. We did expect to find Arctic Primroses in good flower, which we did, along with several Indian Paintbrushes. Beth and I took a few quick close-ups of a nice cluster of the rare pink-blossomed primroses.

A few days later Beth e-mailed us a note that included one of her primrose shots, this one showing a Crab Spider well concealed among the small flowers she had photographed, feasting upon a fly it had captured. Much to my surprise and satisfaction, upon downloading my memory card into the computer, just one of my pictures also showed the very same predator-prey highlight.

This Crab Spider, still yellow from its previous flower visited, waits in ambush on a Queen Anne’s Lace blossom.

My interest in spiders began in a rather unusual way. I was in my senior year at UW-Oshkosh in 1953 and had been assigned to do several weeks of practice teaching in the lab school, a fifth grade class whose regular teacher was the skilled and veteran lab school faculty member, Miss Cozette Groves.

I had just begun my class and was standing next to the teacher’s desk when in tiptoed Miss Groves. She had to retrieve something from her upper desk drawer, slid the chair outward and let out quite an audible gasp. In a loud firm voice she said, “Will whoever put this picture of spiders on my chair please come and get the encyclopedia and put it back on the shelf.”

A few of the boys had learned about their teacher’s intense hatred of spiders. I had learned a valuable lesson; how could I ever teach my future students to become interested in and be tolerant of spiders if I was scared to death of those tiny creatures?

Charlotte and I were leading an early morning bird hike years ago and made a fascinating discovery of a Crab Spider perched in a very advantageous spot on a Showy Lady’s-slipper Orchid in full bloom. There on the edge of the slipper opening perched the spider, just as though it knew precisely where incoming insects would land before trying to get some nectar from the flower, which by the way is impossible because these rare orchids don’t produce any!

A Crab Spider, legs outstretched like a crab’s, waits on a tall Verbena flower for its prey.

I don’t know of a more likely weedy wildflower of late summer on which to observe and photograph Crab Spiders doing their thing than the Queen Anne’s Lace. Often in the past one of these commonly abundant plants, maroon central “target” floret included, supported a white and pink Crab or Flower Spider calmly devouring a bumblebee about twice the size of the spider. A potent disabling toxin, quickly injected into the bee’s body, tends to liquefy the innards of the victim, enabling this spider to take other insects considerably larger than itself.

As I have watched this little master of deceit that resembles a crab, I realized it could move more easily sideways or backwards than forwards. When I gently nudged it with a blade of grass into moving, it suddenly dropped with the aid of its “dragline” to a lower level on the plant. I had assumed from previous experiences with this spider that it never made use of a web in capturing its victims, as do so many other spiders. However, it does continually lay down that vital, sticky, lifeline wherever it walks just in case some force should knock it off its feet. Many cobwebs (not spider webs) that one sees, most likely collecting dust, are in reality discarded lifelines showing that spiders have been there.

I have often been on my knees to study the inch-long masquerader from close range and marveled at its alertness. The raised portion of its head, resembling a turret, contains eight tiny simple eyes that look much like miniature portholes. One assumes that this spider has acute vision at short distances. I wonder if the Crab Spiders have also studied me – huge, two-legged monster – and enjoyed watching that clumsy slow-moving hulk.

It is common during the course of the Crab Spiders’ existence, which may last from sometime in May until just before frost in late fall, for them to be either pink and white or pink and yellow, depending on the color of the flower they have most recently been on. It is thought that it will require several weeks for the same spider to change from white to yellow.

This Crab Spider appears to know exactly where to wait for its prey on a Showy Lady’s-slipper.

Some of the flowers on which I’ve observed Crab Spiders include Hollyhock, Goldenrod, Queen’s Lace, Ox-eye Daisy, Arctic Primrose and Showy Lady’s-slipper Orchid. Surely there are many others.

A reference I especially like and use frequently is Spiders of the North Woods by Larry West. It is one of the very popular North Woods Naturalist Series and is readily available in area bookstores and nature centers.

It would be so wonderful if all people would develop admiration rather than disgust for the lowly spiders. We should be thankful for the roles they play in helping control the populations of many species of insects.