This is a discussion on Do i have a male and female roach? within the Food, Feeders, Live, Frozen, Culturing, etc forums, part of the General Topics category; here's the pic do i have a male and female surinam roach?...
If you recall our discussion on this species, P. surinamensis are all female. They are a parthenogenic species, meaning they are all female and undergo asexual reproduction. They do not need a male to be fertilized. Ever adult is a female, and can make babies all by herself.
There was the possibility of this species being P. indicus... in which case you have the option of males and females.
Let me see what I can do about bringing some specimens in the lab tomorrow and using the dissecting microscope to take ventral pictures of male and female cockroaches for several species. I can't make any guarantees because I have a lot of work to do tomorrow on some wasps, but if I can find the time I'll try to snap some ventral shots. In the meantime, I'll try my best to describe sexing roaches to you.
To identify female cockroaches from males, there are a couple of strategies. These do not apply to all cockroaches, however.
1) Look for styli in males. This is the easiest means of identification in some species (not all, to my knowledge). Every species, both male and female, should have two cerci on their abdomen used as a means of sensation, behaving much like a pair of antennae on their rear end. These often jet out to the side somewhat, but are positioned on one of the last abdominal segments. In a nutshell, you will see two little projections on the cockroach's butt. These will be in every cockroach, male and female...the cerci.
Styli are tiny projections that only MALES have, and these are oriented in-between the cerci. Bare with me here, I know this is a lot of information to follow without pictures. In a nutshell, if you see 2 little antennae like projections on the abdomen, you likely have a female. If you see 4 (2 larger cerci located on the outsides, and the male's 2 styli located inbetween these) then you have a male.
However, this is not true for all cockroaches to my knowledge. If you are uncertain about this, or there seems to be no clear styli in this species, we'll move on to step #2
2) Look at the last abdominal sternite (last segment on the underside of the body closest to the rear-end). This method can actually be used to positively ID sex of late-instar Blaptica dubia and other roaches before they reach adulthood.
If you flip your cockroaches over and look at them from the underside (ventral side) so that you can see their "belly" you can determine the sex. Notice that there are segments on the underside of the abdomen.... the very LAST segment, closest to the cockroach's 'butt', is what is called the abdominal sternite.
FEMALES will have a very large last ventral sternite.
MALES will have a very small ventral sternite.
This is going to take some practice - look at at many as possible and try to examine the differences. If you see no notable differences between any of the roaches, you likely have all female P. surinamensis. If you can see styli, or better yet, differences in the size of that last segment on the underside of the cockroach's abdomen, you know you have males and females and you are dealing with P. indicus.
Here's a quick drawing I found for reference with a google search:
I have no idea what you are talking about with the stick-looking thing by the way... lol
I'll see what I can do about getting real pictures from the dissecting microscope tomorrow. If I am unable, I won't be able to for at least a week. There are surely pictures online that you can use for reference as well if you search images for 'male and female cockroaches' or something of the like.
EDIT: If you can get pictures of the underside of your cockroaches (decent pictures), I can sex them for you as well. Adults only.
Something else I noticed is that one of your adults clearly has longer wings than the other two. This is sometimes a type of sexual dimorphism seen in species as well that can potentially let you determine the gender.
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