Bug o’the Week – Northern Two-striped Walkingstick – a Snowbird Special

Bug o’the Week
by Kate Redmond

Northern Two-striped Walkingstick a Snowbird Special

Howdy, BugFans,

In the recent episode about Saddleback caterpillars, the BugLady mentioned that she (rightly or wrongly) associates the South with a larger number of plants and animals that sting, bite, itch, poison, stab, spray, and spit (sorry, folks).  Here’s another one.

First of all, we’re not talking about the svelte Northern Walkingstick that graces our landscapes here in God’s Country (https://bugguide.net/node/view/2219691/bgimage).  The order Phasmida (aka the order Phasmatodea or Phasmatoptera) contains five walkingstick/stick insect families in North America (“Phasma” means phantom or spirit).  Northern Walkingsticks are in the family Diapheromeridae, and Northern Two-striped Walkingsticks are in the Striped Walkingstick family Pseudophasmatidae.

Thank You, BugFan Joe, for sending pictures from the Deep South and for submitting them to bugguide.net for a species ID.  Here’s what the expert at bugguide said, “The taxonomy of this genus needs to be worked out, but I would lean on these being ferruginea. True A. buprestoides [the Southern Two-striped Walkingstick (STSW)] is supposed to be mostly restricted to Florida and extreme southern GA and AL, and is supposed to have the dorsal stripe much more distinct. But better to leave at genus level for now.”  Our knowledge of the lifestyles of the two species has some gaps in it, but they seem to operate similarly.

Anisomorpha means “unequal form,” and the BugLady guesses that refers to the size difference between males and females.  There are four species in this New World genus – two north of Mexico – and (like the Saddleback caterpillar) they are famous/notorious for their chemical defense system. 

So – the Northern Two-Striped Walkingstick (Anisomorpha ferruginea) (probably) (ferruginea means “rust-colored”).  Like many odd-looking critters, it has amassed a bunch of common and regional names – Prairie Alligator, Musk Mare (she’s a Musk Mare; he’s a Musk Stallion), Western Two stripe, Witch’s Horse, Devil’s Darning Needle (dragonflies are given that nickname, too), Witch’s Hose, Stick Bug, Spitting Devil, Devil Rider, and even Scorpion.  The names come from its appearance, from its defense strategy, and/or from the piggyback habits of the male (she does not carry her young on her back like a loon or opossum or wolf spider). 

NTSWs are found from South Carolina to Alabama, through Texas and Oklahoma, plus Illinois; there are Florida records of NTSWs, but nymphs of the NTSW and the STSW are pretty hard to tell apart (adults can be, too), so those records are considered a little iffy.  Females are chunky, tan/brown/rust, and about 2 ½” to 3” long, not counting the antennae, and males are about 1 ½” long.  NTSWs have straighter, slimmer legs than STSWs, and STSWs are a little larger, come in three color morphs, and (often) have more distinctive stripes (https://bugguide.net/node/view/1767787/bgimage).  Insects’ legs (and wings) are attached to the thorax, and in aid of their twiggy disguise, the walkingsticks’ extra-long thorax allows their legs to be spaced out along its length.  Many, but not all, species are wingless. 

They graze on leaves at night, and they seem to be fond of members of the oak family, but not exclusively.  One source said that when numerous, they can damage/defoliate shrubs; one said that they don’t do significant damage; and the Missouri Department of Conservation Field Guide says (rather optimistically) that “Musk mares help to limit the growth of vegetation. Over time, they help develop vigorous strains of plants that are least hindered by their leaf chomping.”

Some birds, reptiles, mice, ants, and spiders may be discouraged by their chemical assaults, but not all of them, and their eggs are eaten on the forest floor. 

They spend the winter – sometimes two winters – as eggs.  Our Northern Walkingstick drops her eggs carelessly from the treetops, the NTSW deposits them into bark crevices or onto the ground, tucked into leaf litter, and the STSW digs little holes for them.  They hatch and the nymphs feed, mostly unnoticed, until they mature in fall and gather in open areas or on buildings or tree bark https://bugguide.net/node/view/74303/bgimage.  Mating can last from several days to several weeks (and they’re probably monogamous), but the male continues to ride piggyback after his reproductive duties are done.  It has been suggested that the arrangement serves both of them because two sets of eyes looking for predators are better than one. 

They protect themselves with a musky, milky, irritating chemical (anisomorphal) that they produce and spray as a fine mist from a pair of glands in the thorax, just behind the head.  They spray with amazing accuracy – they aim for your eyes, and they can project the spray at least a foot.  They have the ability to spray from the moment they break out of the egg. 

What does it feel like?  According to the Texas Entomology website, “The first account of A. buprestoides’ effect on humans was apparently by Stewart (1937), who wrote about an incident in Texas: ‘The victim was observing a pair of Anisomorpha buprestoides …. with his face within two feet of the insects, when he received the discharge in his left eye …. The pain in his left eye was immediately excruciating; being reported to be as severe as if it had been caused by molten lead. Quick, thorough drenching with cool water allayed the burning agony to a dull aching pain. The pain eased considerably within the course of a few hours. Upon awakening the next morning the entire cornea was almost a brilliant scarlet in color and the eye was so sensitive to light and pressure for the next forty-eight hours that the patient was incapacitated for work. Vision was impaired for about five days.’ (Thomas 2003).”  Inhaling the chemical is unpleasant, too. 

The late, great entomologist Thomas Eisner noted that the STSW “is the source of one of the most noxious defensive secretions known to be produced by an insect.”  He prodded and pinched them in the lab and reported that it didn’t take much hassling for the STSW to react, that the insect could activate one or both glands, and that it could direct the spray precisely at the probe that poked it.  The sight of a bird closer than eight inches away caused an STSW to spray without waiting for the bird to touch it, but the walkingstick did not react to a waving bundle of feathers or colored cloth.  Eisner wrote, “The insect is obviously programmed not to waste its secretion by being unduly ‘trigger happy.’”  Some mammals simply outlast the STSW, waiting until it has sprayed about five times and its reservoir is empty (it takes a week or two to generate enough spray to refill a reservoir); a few test rats simply got used to the spray and ate the walkingsticks; and STSWs have been found in bear scat.   

About anisomorphal Eisner said that “Anisomorphal is also produced by a mint plant, in which the compound is sealed within tiny capsules embedded in the leaf tissue.  The capsules are designed to rupture and release their repellent contents when herbivores bite into the leaves.”

Admire these guys from afar – or wear safety glasses!

Kate Redmond, The BugLady

Bug of the Week archives:

Bug o’the Week – Wetland Homage IV – Water Scorpions by Kate Redmond

Bug o’the Weeku
by Kate Redmond

Wetland Homage IV Water Scorpions

 Howdy, BugFans,

If wetlands are the transitional spongy/submerged/semi-submerged/sometimes-submerged areas between high ground and deep water, what might some wetlands look like?  Swamps are wet woodlands, while marshes are wet areas with standing water whose vegetation is mostly non-woody.  Peatlands like bogs, which have no sources of water other than precipitation and run-off, so water stalls there and becomes acidic; and fens, which are fed by springs and are often alkaline.  And then there are sedge or wet meadows, scrub/shrub thickets, and more (for more info, see https://dnr.wisconsin.gov/topic/Wetlands/types.html) and https://www.wisconsinwetlands.org/learn/about-wetlands/wetland-types/.


The long (about 2” not including the “tail”), lean, well-camouflaged Brown Water scorpion (Ranatra fusca) is in the order Hemiptera, and thus, it can legally be called a “bug.”  It’s in the family Nepidae, which includes about 13 species in North America and 270 worldwide, including some broader-bodied species like https://bugguide.net/node/view/2205541/bgpage and https://bugguide.net/node/view/818188/bgpage that resemble the Water scorpion’s distant cousin, the Giant water bug https://bugguide.net/node/view/1657638/bgimage

Water scorpions have simple/incomplete metamorphosis, looking when they hatch pretty much like they will as adults, adding a few parts (the wings and the “naughty-bits”) as they molt (five times) and mature.  As is typical with insects that practice simple metamorphosis, both the adult and the immature water scorpions live in the same habitats – muddy-bottomed ponds and very slow streams with submerged vegetation – and both dine from the same menu.  What’s sauce for the goose is sauce for the gander.

They hang out, usually head-down https://bugguide.net/node/view/1682158/bgimage, on aquatic vegetation and in the detritus just off-shore, gripping with their second and third pairs of feet, legs bent.  Their passage through the water is sloth-like, and swimming, also using their second and third pairs of legs, is not their forte.  In fact, in A Guide to Common Freshwater Invertebrates of North America, author J. Reese Voshell, Jr. says that water scorpions are so sedentary that not only do algae and micro-invertebrates form colonies on them, but other aquatic insects may deposit eggs on them!  This immobility is part of their “stealth” hunting tactic.  

They’re equipped to fly https://bugguide.net/node/view/126649/bgimage, and fly they do, but not often, and almost always at night (say most – but not all – sources), and they must emerge and spread and dry their wings before take-off.  They are known to bask in the sun.

Despite their resemblance to the terrestrial, vegetarian walking sticks https://bugguide.net/node/view/1874213/bgpage, water scorpion are carnivorous, ambushing aquatic invertebrates like daphnia, seed shrimp (ostracods), backswimmers, water boatmen (a favorite), and even tiny fish fry and tadpoles.  They spot their prey with protruding compound eyes https://bugguide.net/node/view/1679712/bgimage, “lunge” at it by straightening their legs suddenly (without letting go), nab it with mantis-like front legs, stab it with a short beak (which is capable of piercing human skin, so handle with care), and inject it with tranquilizers and tenderizers.

Two long filaments on their south end are not stingers, but they explain the “scorpion” part of the name.  These lock together to form a breathing tube, the tip of which the bugs position just at the air-water interface.  Oxygen seeps down the tube and is stored as a bubble under the fore wings, against the abdomen.  They can use that bubble of air when they want to go deeper than their “snorkels” will reach (the structure of the filaments doesn’t allow water to enter), and in well-oxygenated water, oxygen suspended in the water can diffuse into the bubble, giving the insect extra breathing time. 

According to a website called the Pond Informer, “The mating process for water scorpions typically occurs in the months of April and May. To attract a female mate, a male will perform stridulation. He will create a chirping sound that is produced when he rubs his legs against his body, similar to crickets rubbing their wings together. Once he has attracted a mate, the male water scorpion will lay diagonally across and on top of a female, and he will grab onto her thorax using his front legs. Shortly after mating has occurred, the female will deposit her eggs – she usually does this around dusk.” 

Her eggs, which are laid at or above the water’s surface in plant stems, rotting wood, or in damp spots like algae and moss near the water’s edge, have respiratory filaments that protrude from the eggs and allow them to take in oxygen https://bugguide.net/node/view/1861200/bgimage, and some sources say that the eggs can also glean oxygen from the plant stems they are inserted into.  She can lay about 30 eggs in one evening.  Newly-hatched nymphs make a dash for the water’s surface (there’s no room for breathing tubes in the egg https://bugguide.net/node/view/570259/bgimage).  

Water scorpions overwinter as adults, under the ice, equipped with a chemical defense against freezing.

Fun Fact about Water scorpions – an alarmed individual may squeak, and then it may play dead, and it may squeak if it’s scooped out of the water.  

Another Fun Fact about Water scorpions – they can sense the depth of the water they’re in by the water pressure.

Kate Redmond, The BugLady

Bug of the Week archives:

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