Friday, July 29, 2011

The Stick that is Not a Stick…

By: Lacy Sellent, Writing Fellow at the Cable Natural History Museum


Before heading off on a hike in the great outdoors, you may want to learn more about walking sticks.  Knowing the typical length of a walking stick, along with knowing where to look in order to find one, are both good places to start.  It also may be beneficial to know what they eat…Wait, what?

As you may have noticed, I’m not talking about a wooden walking stick.  No, I am talking about the actual creepy crawly insect in the order Phasmatodea.  The walking stick is an insect that tricks predators, such as birds, into thinking that it is just a stick—not a tasty meal.  Depending on the species, the walking stick may be green or brown.  The green species match the color of the leafy bushes that they hide in.  The brown ones can blend in among the twigs and branches of trees.   

These insects (at least the ones in Wisconsin) range in size between half an inch and several inches—depending on the species, gender, and age of the insect.  The male is shorter than the female, but both sexes can reach some amazing lengths.  Some species from across the globe have been known to grow as long as twenty-one inches!  Here in Wisconsin we won’t be seeing any twenty-one inch walking sticks, but we can still observe their amazing natural disguise.   

The walking stick, like most living things, has excellent physical and behavioral adaptations that help it survive in its habitat.  One clever behavioral adaptation of the walking stick is to sway back and forth when perched on a twig or leaf.  The swaying motion helps it to better mimic how a tree branch moves in the wind, and adds accuracy to its disguise.  Not only does the walking stick have the benefit of physically looking like a stick, but it also acts like one!

During the day is when you would be most likely to spot one swaying with the breeze. This is because the walking stick is an insect that does its moving around mostly at night.   At night it will “branch out” to forage for food.  This insect is an herbivore, so it’s not uncommon for them to feed from the same plants that also provide them with shelter. 

The distinguishing characteristics of this insect don’t stop at its use of camouflage.  The walking stick is also one of the few species to reproduce without the aid of a male.  All a female has to do is lay the eggs and they will all be born female.  The males are not only smaller in size, but also fewer in number.  If a male does happen fertilize the eggs there is still only a fifty-fifty chance that some of the eggs will be male.  Because of this unique characteristic, there are some species of walking sticks that are entirely female. 

The walking stick is truly a fascinating insect—and it is one that lives in your own backyard!  The next time you walk by a bush, look closely.  With a watchful eye, you may be able to spot the stick that is not a stick.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, The Joy of Birds: Feathers in Focus opened in May, 2011. Find us on the web at http://www.cablemuseum.org/ to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.


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