Fig. 5: Dasypogon diadema, beginning of an oviposition [video recorded]

The behaviour of the females changed distinctly before and during the oviposition. They became more active, frequently flew up for short distances, and ran over the sandy soil between the vegetation. Their wings were spread and vibrated frequently, abdominal pumping was also sometimes observed. The females trailed their ovipositor across the ground and frequently stuck them into the soil. As soon as a female found a suitable place, she rapidly moved the ovipositor around, curled her abdomen under herself, and pushed the blunt ovipositor down into the soil (Fig. 5).
The ovipositor was normally sunk to the full depth of the abdominal length less the first and second segments. As the abdomen was pushed so deep that the wing tips touched the ground, the wings were spread. The tip of ovipositor therefore reached a depth of 10-13 mm at which time the female stiffened for 5 - 10 sec., with spread wings and legs. At this she vibrated her abdomen and withdrew it.
Finally she smoothed the surface with her ovipositor and flew away, often to select another site for further egg deposition. In the meantime (2 min. on average) she sometimes excreted a milky and yellowish liquid. After the female had repeated her oviposition several times, she rested for a longer period of time.
The oviposition of a female which had copulated two days before was recorded in the laboratory. The results are summarised in the following table:

Table I. shows that D. diadema deposited her eggs (or "cocoons", see next paragraph) at regular time intervals, which were interrupted by longer periods and that the frequency of ovipositions decreased over a period of days. Field observations were also made, but it was impossible to follow the females for a long period of time.
Oviposition was observed between 11 a.m. and 7:20 p.m. in Darmstadt. Eggs were usually deposited in shaded areas, both in the field and in the laboratory.