Sunday, July 20, 2014

Long Tall Timema Green

bunch of legs
kinda squishy
That makes it a bug, right?   

I say, "I don't do bugs" but the long, tall green one that clung to the Adirondack chair on my porch in May was just too interesting. I'd never seen an insect like this, so maybe it was one of those freaky larval stages that mimic the colors or markings of the adult insect but all the parts are twisted around to do something else. Like the transformer toys I would find wedged in the back seat of the Jeep after long trips with the boys. Alien yet disturbingly familiar. The god in charge of metamorphosis must be a boy.

A greater anglewing katydid climbs the barn.
The appendage at the back of its abdomen makes this a female.   
I saw this same color - a shade of spring grass -  a few years ago when I found a giant insect methodically climbing the red barn door at the Dipper Ranch. It looked like an origami creature with crimped pipe cleaners for legs. Legs so long it had to move them one at a time to keep them from tangling. A slow climber, it gave me plenty of time to fetch my favorite bug book - Kaufman Field Guide to Insects of North America.

When I returned to the farmyard intent on ID, the insect had barely made it past the barn door handle. A brief glance at Kaufman's leaf hopper page - no origami insects there. Checking the grasshopper section - nope. I moved the origami insect to the bottom of the barn door to give me more time, after all, there's an awful lot of insect species in North America if your approach to ID is flipping through all the pages. Just as it restarted its climb, I found two glorious pages of katydid illustrations. Yes, this was a katydid so cooperatively approaching knee level where I could compare it to colorful plates and descriptions. Was it the fancifully named "slightly musical cone head" or "rattler round-winged katydid"? No, it had a practical name - the greater anglewing katydid.

Grandmother Grundy [a nursery rhyme]
Oh Grandmother Grundy,
Now what would you say
If the katydids carried
Your glasses away?

Carried them off
To the top of the sky
And used them to watch
the eclipses go by?   
For most of my life, I'd never actually seen a katydid, just heard them described as kleptomaniac pests in a nursery rhyme. At last I knew what a katydid was and it didn't look capable of eyeglass thievery. Maybe it's their habit of appearing at the end of the long dreamy days of summer that inspires such extravagant names or exotic fairy tales for some insects. But their real life is even more incredible than nursery rhymes, especially insect metamorphosis - the transformation from young insect to adult.

Could the mysterious green thing on the Dipper Ranch porch be a juvenile form of a katydid? Not only were both the small and large insects the same bright green, but they also shared a pattern of many white dots and a few white lines.  A search of the Bug Guide website, however, showed otherwise. Katydids undergo simple metamorphosis so their nymphs are just small versions of the adult form - katyminididdies.  Neither young or old katydids were constructed like the long, tall green thing on my porch.

Not being a bug expert (see, I call them "bugs"), I didn't bother counting legs, measuring antenna length or noting the shape of the leg segments, I just started flipping through the pages of Kaufman's guide again. Page after page of interesting distractions but not the brilliantly green and fortunately still porch insect. Suddenly, there was a perfect match, the only green photo on the stick insect page - a Timema. Never heard of them.

Timemas are usually the same color as their host vegetation and their long body shape with longitudinal stripes may further camouflage them especially on long narrow needles such as on Douglas fir or chamise.   
Timemas are walking stick insects that eat and camouflage themselves on twigs and leaves - often long, narrow leaves on which they align their likewise bodies. Like katydids, they undergo simple metamorphosis - baby Timemas look like adult Timemas (fabulous photos of a walking stick insect hatching here). Wingless and mostly found in the western states of the US, a few Timema species are parthenogenic - all females asexually reproducing daughters - and have been studied to understand how asexual populations appear to move farther and faster than sexual populations of the same or similar species to colonize new areas (Law and Crespi 2002).

Female Timema - the paired 'terminalia' is long and symmetrical.   
The long, paired appendages on the Timema I found on my porch make it a female so we can't get into the interesting investigation as to whether this is a parthenogenic population or not. This individual is probably a California Timema because it was found in the Santa Cruz Mountains, it has white stripes on the side rather than dorsally, and the nearest probable host vegetation at the Dipper Ranch are oak trees. California Timemas reproduce sexually.

The discovery of Timemas occurred only over the last 100 years, so there are no nursery rhymes for this insect. But we could make one up.

Timema, timema
at rest on my porch.
You've sent me researching
your life like a dork.

Insect metamorphosis
- simple and complete - 
I'd forgotten the details,
an amazing insect feat.

The next time I see a new insect
I will ask
"Can I see your baby photo?"
to make identification an easier task.

Caterpillar of a sphinx moth - similar color green as the Timema but this is an insect that undergoes complete metamorphosis with the caterpillar larvae looking much different than the adult flying moth. I found this 7 cm long x 1 cm wide specimen on the Dipper Ranch on June 2, 2014.   
Greater anglewing, Microcentrum rhombifolium
California timema, Timema californicum

Kaufman Field Guide to Insects of North America, Eric R. Eaton & Kenn Kaufman, Houghton Mifflin Company, 2007.

Bug Guide website Genus Timema page

Law, Jennifer H and Bernard J. Crespi, The evolution of geographic parthenogenesis in Timema walking-sticks, Molecular Ecology (2002) 11, 1471-1489.


  1. A fine post. Timema faces often remind me of Oecanthus tree crickets, which are weirdos too, that don't do instars but grow continuously.

  2. It was great meeting you at the Conference today. I have a feeling that with my four year old's propensity for bringing bugs for me to look at, I'll be looking at this more than once.......

  3. Thanks Neera. I was thinking about your intrepid son on the way home. I recommend any of the books in the Eyewitness Books series , or Spiders in Your Neighborhood , or any of the small Golden Book series about nature.


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