Distinguishing adult G. Portentosa large nymphs from adults

B

Brandon's Bugs

First Instar
Is there any one trait that can be used to distinguish adults from late instars in G. Portentosa? I have found a very small male (maybe a sneaker male) with small horns mating with female, I would have thought he was a juvenile if I had not seen him mating.

 
Thanks, but it is my experience that the color pattern method does not always hold true for nymphs that are one or two molts away from adulthood. I have watched roaches with no white spots or bands go through a molt.

 
I had this problem when I was sorting and counting adults in a new colony the Zoo received (104 adults, whew!). A lot of the adults were small and relatively narrow-bodied, and it was really tough to distinguish them from the subadults sometimes!

The characteristics I looked at were:

- coloration (not perfect, but in all the lighter color forms the adults' background color and black spots are distinct from the darker nymphs).

- pronotum thickness, shape, and rough/dimpled texture... nymphs tend to have flatter, smoother pronota.

- hissing (of course, not all of them wanted to do that).

- thickness and hairiness of antennae in adult males.

 
If I have a roach and I'm not sure if it's an adult, the first thing I do is check the ventral abdominal structures and coloration. Immature hissers particularly do not have the adult "color scheme" on their belly, and the segmentation of an adult female has a much more complex, 3-dimensional appearance to it. I will get some comparison pictures later today.

 
Subadult male G. portentosa:

jgWPsyN.jpg


Adult male G. portentosa:

OstwieD.jpg


Subadult female G. portentosa:

XESxFh6.jpg


Adult female G. portentosa:

Wsvm6cK.jpg


 
Thanks Zephyr, that is very helpful. It looks like everything starts to open up like a flower blooming. Now I will be able to pull out those tiny adult males in my colony.

 
You must log in or register to reply here.
Back
Top