“This thing squirted me in the eye when I picked it up to look at it, and I had to go to the ER. Glad I had someone to drive me; I couldn’t see because it burned and hurt so much! One eye was so irritated and swollen I couldn’t see out of it for the first day and a half, but it is getting better now, and the doctor tells me it should be back to normal in a couple more days.”
Twostriped walkingsticks may look harmless, but they have a pair of special glands on their back, just behind the head (see arrow in photo), that can squirt a smelly defensive spray up to 15 inches or more. These slow-moving, wingless insects use this spray to defend themselves from predators of all sizes: ants, birds, possums, cats, even people. They can aim accurately and can discharge either one or both barrels. Over the years I have spoken with several folks who experienced this firsthand, and they all insist it was a painful experience. More commonly, it is inquisitive pets that get squirted. The spray irritates all types of mucus membranes: eyes, nose or mouth, fortunately symptoms subside after a few days.
Twostriped walkingsticks are unusual creatures, even for stick insects. Mature females are only 2.5 to 3 inches long and males are much smaller. Usually, when you find a female, she will have a male riding on her back. Both sexes can squirt the defensive spray, but other species of stick insects, which are usually longer, do not have this ability.
Twostriped walkingsticks are most often encountered in late summer and fall after they become adults. Because they are wingless, these insects are spottily distributed. Miss Lonnie may have them in her yard, while none of the other members of her garden club have ever seen one. They feed on a wide variety of leaves, mostly tree leaves, but damage is usually minor. On rare occasions local population explosions result in high enough numbers that they cause significant defoliation of ornamental shrubs such as aucuba and azalea.
Folklore: As a child, I was often told praying mantids were called “devil’s horses” because if you got too close to one, they would spit in your eye and blind you. As a budding entomologist, I was skeptical. Despite my best efforts, I could never get a praying mantis to spit at me and none of my bug books mentioned praying mantids having this ability. Although we also had a few species of stick insects where I lived, we did not have twostriped walkingsticks, and I did not learn about these until years later. I was photographing a mating pair and was using a pencil to align the male when he sprayed while I was watching through the closeup lens, giving me a good look at the spray while also protecting my eyes. So, the tales I was told as a child about an insect that could spit in your eye and cause blindness were true! They just had the insects mixed up, which is easy to do with mantids and stick insects, and fortunately, the blindness is temporary. Twostriped walkingsticks are called by various local names, including musk mare, prairie alligator and devil’s horse.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
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