2017 January 1

 

   Jeremy Tatum writes:  It is a long time since I have seen a firebrat in my suite, but one turned up this morning.  There is a problem.  Is this the Common Firebrat Thermobia domestica, or the Grey Firebrat Ctenolepisma longicaudata?  I showed both species in the 2014 November 1 posting.  Typically C. longicaudata is uniformly grey, whereas T. domestica is very well marked.  The specimen shown below looked uniformly grey at a casual glance with the unaided eye, but the photograph shows some patterning.  It seems to be not sufficiently uniformly grey for  C. longicaudata, but not well enough marked for T. domestica.  One needs some structural feature apart from colour to distinguish between the two.  I suspect the following criterion might work:  Abdomen shorter than thorax =  T. domestica.  Abdomen longer than thorax = C. longicaudata.  If that is a reliable criterion, then I’d call the specimen below C. longicaudata.

 

  Another small problem is that C. longicaudata is often called the “Grey Silverfish” – although it is much more similar in appearance to the Common Firebrat than to a Silverfish.  Both of the firebrats like warm places.  The Silverfish Lepisma saccharina likes cool places, and is easily distinguished from the firebrat by its short cerci.  I have never seen a Silverfish in my apartment building.

 

Grey Firebrat Ctenolepisma longicaudata (Thy.: Lepismatidae))   Jeremy Tatum