There is evidence that T. calvus is attracted to the pheromone of the male (I have captured female T. calvus using Podisus maculiventris pheromone in traps)and mounts the female when she arrives. This behavior ensures she will be at the oviposition site of the female P. maculiventris. I have also observed the female P. maculiventris attempt to dislodge the T. calvus female with no success. In the lab I have exposed P. maculiventris eggs to T. calvus females and they were able to parasitze the eggs without the phoretic behavior (but that is in the lab). This is the only host T. calvus uses so I guess this evolved as the "lazy way" to the egg mass.

When you noticed the host attempt to dislodge the female physically without success, did she (the host) then try any other methods (such as delaying her own oviposition, emiting any chemical substances, etc.) to try to delay/prevent the wasp female from ovipositing? If not, this might give the wasp a comparative advantage in the short-term (this "lazy way" as you call it). In exclusive host/parasitoid relationships over the long-term, we might expect to see an evolving relationship where both species tend to ensure the survival of each other because of their mutual dependence.

I did notice that some times the female would spread her eggs in a trail instead of the usual mass or raft. The following papers will probably interest you and provide more information than I can. "Reproductive Biology and Behavior of Telenomus calvus (Hymenoptera: Scelionidae), a Phoretic Egg Parasitoid of Podisus maculiventris (Hemiptera: Pentatomidae), D.B. Orr, J.S. Russin, and D.J. Boethal, (don't know the publication date).", and "Influence of Host Pheremone on Egg Parasitism by Scelionid Wasps: Comparison of Phoretic and Nonphoretic Parasitoids, R. Bruni, J. Sant'Ana, J. R. Aldrich, and F. Bin, Oct 1999."