Gromphadorina portentosa

I found myself with a few spare moments this weekend, so I decided to finally put together a white box and see what I could do with it.  And what better subject for a white box maiden voyage than Gromphadorina portentosa, the Madagascan hissing cockroach.  Grotesquely beautiful, it also presents a challenging subject for flash-based macrophotography because of its hard, shiny exoskeleton that produces strong specular highlights with all but the most highly diffuse of light sources.  It was also the only live subject I had on hand at the moment, other than a few larval noctuids – not nearly as impressive as these behemoths!  There were some early glitches – the enormous size of these insects made for long working distances, with the result that my box was almost too small!  However, placing the subjects at the back of the box allowed the camera lens and flash units to sneak just inside the front drape, and the closer shots went more smoothly.  I’m quite happy with the results – at least as a first attempt, and I think the method shows even more promise for some preserved specimen photographs that I am planning.

The males, of course, have “horns” on the pronotum, but one thing I had never noticed before is the well-developed lip at its anterior edge.  This is certainly an adaptation to the “shoving” matches that males engage in with each other frequently.  This face-on shot shows him for the formidible opponent that he is!

Sexual dimorphism is fairly evident in this species, as least compared to your average cockroach.  Like most insects, females tend to be a little larger, especially when they are gravid as the one below appears to be.  In my colony I note that they also tend to be more uniformly dark in color than the males, although that is not quite so evident with this particular female.

The big difference is, of course, the weakly developed pronotal protuberances.  Females don’t engage in the shoving matches that males do, so there is no need for the heavily armed pronotum.  Nevertheless, small pronotal humps are still found in the adult females.  Note also the lack of a well-developed lip on the anterior edge of the female pronotum.

Photo Details: Canon 100mm macro lens on Canon 50D, ISO 100, 1/200 sec, f/8-11, indirect MT-24EX flash in white box.

Copyright © Ted C. MacRae 2010

Add to FacebookAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to TwitterAdd to TechnoratiAdd to Yahoo BuzzAdd to Newsvine

Email to a friend