Greetings I don't know if this is the right place to post this because I'm not certain how it is classified or if it can come under many headings. So please move this if it is better suited elsewhere. I watched a video on pbs.org a few years ago and since I am just now writing here about it, you would be correct in concluding it had a powerful impact on me, creating many questions. The video was confined mostly to the insect world but it is my understanding similar events occur in slightly higher animals. What I am referring to is the complete, or what appears to be complete, reprogramming of a living thing to cease working in it's own behalf or for that of it's offspring when it has been injected by some neurologically active compound usually accompanied by the eggs of the injecting invader. Often the change in behavior is very profound and extremely specific such as building a nest that could not possibly be utilized by it's own offspring but is exactly what the invader's offspring requires. The change is far more specific and profound than pictures or videos I have seen for example of spiders and the webs they weave when exposed to various drugs. My question is how is it possible, by what mechanism have compounds evolved that are so specific as to cause such complex and detrimental behavior in the host? I apologize for not being able to link the original video. I can no longer find it. I'm hoping someone else here finds this as fascinating as I do and can point to some printed material or other videos of this nature as well as give some insight into this amazing process.