10 Fascinating Facts About Stick Insects

Interesting Behaviors and Traits

Green stick insect on branch.

RooM/kuritafsheen/Getty Images

Who isn't fascinated by stick insects, of the order Phasmatodea (also known as phasmids and walking sticks)? You know the ones, those subtropical and tropical bugs that look just like branches—until those twigs get up and walk away from you, that is.

Learn more about these remarkable insects. Here are 10 fascinating facts about stick insects, guaranteed to be true.

1. They Can Regenerate Shed Limbs

Should a bird or other predator grab hold of its leg, a stick insect can still make an easy escape. The imperiled insect simply gives up the leg, using a special muscle to break it off at a weak joint. This defensive strategy is known as autotomy. Juvenile stick insects will regenerate the missing limb the next time they molt. In some cases, adult stick insects can even force themselves to molt again to regain a lost leg.

2. Stick Insects Reproduce Without Males

Stick insects are a nation of Amazonians, able to reproduce almost entirely without males, or parthenogenetically. Unmated females produce eggs that become more females. When a male does manage to mate with a female, there's a 50/50 chance their offspring will be male. A captive female stick insect can produce hundreds of all-female offspring without ever mating. In fact, there are species of stick insects for which scientists have never found any males.

3. Stick Insects Even Act Like Sticks

Stick insects are so named for their effective camouflage among the woody plants where they feed. They're typically brown, black, or green, with stick-shaped bodies that help them blend in as they perch on twigs and branches. Some exhibit lichen-like markings to make their disguise more authentic. But here's the capper: Stick insects even imitate twigs swaying in the wind by rocking back and forth as they move.

4. Their Eggs Resemble Seeds

Stick insect mothers aren't the most maternal. They typically drop eggs randomly on the forest floor, leaving the youngsters to whatever fate befalls them. Don't be so quick to judge mama stick insect, though. By spreading her eggs out, she lessens the chance that a predator will find all her offspring and eat them all. The eggs resemble seeds, so carnivorous predators are less likely to take a closer look. Some stick insects actually make an effort to hide their eggs, sticking them to leaves or bark or placing them in the soil.

5. Nymphs Eat Their Molted Skin

After a nymph has molted, it's vulnerable to predators until its new cuticle darkens and hardens. The castoff skin nearby is a dead giveaway to enemies, so the nymph quickly consumes the shriveled exoskeleton to get rid of the evidence. The stick insect nymph also recycles the protein by eating its molted skin. It took a lot of energy to grow that exoskeleton, so there's no sense in letting it go to waste.

6. Stick Insects Aren't Defenseless

Stick insects aren't venomous, but if threatened, one will use whatever means necessary to thwart its attacker. Some will regurgitate a nasty substance that will put a bad taste in a hungry predator's mouth. Others reflex bleed, oozing a foul-smelling hemolymph from joints in their body. Some of the large, tropical stick insects may use their leg spines, which help them climb, to inflict some pain on an enemy. Stick insects may even direct a chemical spray, much like tear gas, at the offender.

7. Their Eggs May Attract Ants

Stick insect eggs that resemble hard seeds have a special, fatty capsule called a capitulum at one end. Ants enjoy the nutritional boost provided by the capitulum and carry the stick insect eggs back to their nests for a meal. After the ants feed on the fats and nutrients, they toss the eggs onto their garbage heap, where the eggs continue to incubate, safe from predators. As the nymphs hatch, they make their way out of the ant nest.

8. Not All Stick Insects Stay Brown

Some stick insects can change color, like a chameleon, depending on the background where they're at rest. Stick insects may also wear bright colors on their wings but keep these flamboyant features tucked away. When a bird or other predator approaches, the stick insect will flash the vibrant wings, then hide them again, leaving the predator confused and unable to relocate its target.

9. Stick Insects Can Play Dead

When all else fails, play dead, right? A threatened stick insect will abruptly drop from wherever it's perched, fall to the ground, and stay very still. This behavior, called thanatosis, can successfully discourage predators. A bird or mouse may be unable to find the immobile insect on the ground or prefer living prey and move on.

10. Stick Insects Are the World's Longest

In 2008, a newly discovered stick insect species from Borneo broke the record for longest insect (which had previously been held by another stick insect, Pharnacia serratipes). The Chan's megastick, Phobaeticus chani, measures an incredible 22 inches with legs extended, with a body length of 14 inches.

Sources

  • Marshall, Stephen A. "Insects: Their Natural History and Diversity." Firefly Books, 2006.
  • Gullan, P.J., and P.S. Cranston. "The Insects: An Outline of Entomology." Wiley-Blackwell, 2010.