These are images of a female Thread-waisted Wasp called a Black and Yellow Mud Dauber
, Sceliphron caementarium
. I noticed that many of the images of this species on the BugGuige are not sexed and that most of them appear to be females.
Here is a link to this wasp's short video: (3.5min. duration) ♀ Black & Yellow Mud Dauber - Sceliphron caementarium
Any images involving burrow interactions, mud-building construction or predation are probably going to be female wasps. From the clearer images of the mating pairs or even the threesome-sexual interactions, you can see a bit of the dimorphism of this species. Petiole colors and overall wasp sizes are always somewhat variable between locations and also in any one location.
Here are three ways to sex these wasps and there may be more methods. This requires clear images of the abdominal area. All numbers are approximations, based on my limited skills. By default, the female wasps will generally have larger abdomens, but they can also be larger wasps in overall size, which may add to some confusion. The dimorphic differences are subtle and very hard to determine, without accurate measurements or direct comparisons.
1) - average abdomen length (male's = 0.65 to 0.85 times the length of female's)
2a) - abdomen (A) to petiole (B) length ratio (A/B) - (male = 0.6 to 1.3, female = 1.5 to 1.9)
2b) - In the case of the wasp pictured above, this ratio is approximately: A/B = 1.78
3) - abdominal segment number and segment width (lateral or dorsal view) - (male = 7 short tergites, female = 6 long tergites)