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Odd Bug Out: A Leaf Insect Discovery

July 30, 2014

Every day amazing things are happening at the Museum, and one such thing happened on Monday. I received an email from Bill Reynolds,  the Coordinator & Curator of the Arthropod Zoo, with the following text:

Subject: Odd bug in our stick insect colony!

WE have a male in one of our colonies!!!!

Thought it may be note worthy for the blog/twitter.

Of course when one receives an email like this one immediately goes in search of the source, and what I learned was pretty amazing.  I knocked on the door and was led into the hustle and bustle of the Arthropod Zoo headquarters. Immediately, I am greeted by Bill, staff and intern. They were ready to reveal the mystery of the “odd bug”.  They gently placed a container with leaf insects down in front of me, I looked closely and had to really focus to find the moving critters. A leaf insect is pretty exciting just by itself. For those who are unfamiliar I was looking at the giant leaf insect, which is a large species of leaf insect with the scientific name Phyllium giganteum, and looks exactly like a walking leaf. They are true masters of mimicry! Their camouflage is one of the best systems in nature – not only does their body have leaf “veins”, some of them develop brown edges that mimic a damaged leaf.

Juvenile Female Leaf Insect

Juvenile Female Leaf Insect

I leaned over to get a closer look, and the intern pointed at one slowly moving among the branches. “You see that one?” “That’s a female and the one next to it (she points to the other side) isn’t.” I stared at the two and immediately started to notice the differences – one seemed thinner, had antennae, and translucent wings. It clearly did not look like the others. “So…is something wrong with it? It looks really tiny next to the others,” I commented. At this point, I am still not quite understanding what I am looking at, until the intern points and says, “That’s not suppose to be male.”  And then the light bulb goes off and I remember Bill explaining that leaf insects reproduce asexually, and here I was staring at a male. Wait! Aren’t they all suppose to be ladies?

Phyllium giganteum - egg from lateral

Phyllium giganteum – egg from leaf insect

Upon investigation I discovered  that some stick insects produce offspring in a very different way: the females can produce young without needing a male! The eggs she produces are unfertilized. They do develop properly and grow into an adult female stick insect. The production of a new individual out of an unfertilized egg is referred to as parthenogenesis. The female that produces these eggs is called parthenogenetic, and is a form of asexual reproduction.  It is particularly common amongst arthropods and rotifers, and can also be found in some species of fish, amphibians, birds, and reptiles.

In an email, Bill Reynolds explained the history and discovery of this mystery male:

A few years ago, the Arthropod Zoo received 3 adult Phyllium giganteum for our annual Bugfest event.  Knowing these insects were parthenogenetic (all female and asexual), we kept the eggs and 2 years later, they hatched!

After several generations in captivity, we have had good success with these insects and as expected, all have been copies of their mothers – until today, 28 July 2014!  While routinely caring for our colony, an oddball individual was picked up by an intern, she came running into my office …. “Look!,” She exclaimed,…”We have a male Phyllium!”  At first I thought she had to be mistaken, but she was RIGHT!

The existence of males for this insect species was not proven until 1994.  The males are slim, possess long antennae, long translucent green flight wings, and brown legs.  The function, purpose or reproductive success of males in this species is debated, but nonetheless, we have a very special bug.

 Why is this such an amazing discovery?

Males are very rare, especially in captivity.  How this occurs is a very complex topic and researchers are still trying to wrap their minds around it. According to, the leaf insect can be found in tropical forest in Malaysia. This species consists of only females. Two preserved museum specimens of Phyllium giganteum males have been found, but as these have never been seen alive or tested for reproductive capabilities it remains unclear what role males play in natural populations of this species. While there has been some documented cases this discovery is pretty spectacular for us; all thanks to the keen eyesight of an intern.  Don’t worry… he is definitely getting the royal treatment in the Arthropod Zoo.

Here is a close-up of our mystery man and comparison with his female counterpart.

Notice the antennae, wings, and brown legs of the male leaf insect.

Notice the antennae, wings, and brown legs of the male leaf insect.

Notice the female leaf insect on top and male on bottom.

Notice the female leaf insect on top and male on bottom.

For more information about the Arthropod Zoo and Parthenogenesis:

5 Comments leave one →
  1. permalink
    July 30, 2014 4:28 pm

    I love this  

  2. kitty! permalink
    July 31, 2014 12:16 pm

    So are you going to have cameras on him 24-7, so if he commits an act of genetic diversity with one of the females we’ll have the first record of it ever ever ever? That would be so cool!

    • August 7, 2014 10:07 am

      We will not have him under 24-7 surveillance, but we do have him housed comfortably with a couple females to more easily track any possible reproductive activities and subsequent products.


  3. jgalfano permalink
    August 7, 2014 9:30 pm

    This is such an amazing and interesting find! Kudos to the keen eye of the intern. She should be very proud of her almost unheard of find. Can’t wait to hear the ongoing story!

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