Or build Counter Espionage Centers on each planet. Personally i nevr have a problem with enemy spies so i don't evr build those. I find that i cn out produce my enemies ith spies so thy never have enough to send my way. Or they just don't think I'm worth looking at.   

I own 80% of the galaxy. I have a military rating of 340, a economy rating of 180, atech rating of 324.

No one is even close to me, everyone else is weak in all areas.

I have 3 options:

1. Elimiante the spies.
2. Eliminate all 3 remaining races.
3. Find who sent the spies and eliminate them.

I really want to know how I can find out who sent the spies. I only have 3 races I need to eliminate before I have a conquest victory. If someone sent the spies, I'll just eliminate them. It'll be a quick victory.

I have hundreds of planets I own, so It would be a bit bothersome to spend 50 hours out spying all the spies on my planets.

The thing is, at the moment I personally don't care if someone is spying on me. My military might is 3 times the power of all the 3 major remaining races combined.

I want them to stop or, I just want a good excuse to declare war on someone.

Remember, I'm a saintly race, so I must have a good excuse to eliminate

Honestly, I like being a saintly race, I don't really want to go and eliminate everyone without a good reason. I want to find who sent the spies and eliminate them.

Since you own 80% of the galaxy you will get a saintly influence victory. Like Burress said, you can not find out who sent the spies. And at the stage of the game you are at, trying to prevent spies will not be worth it.

You didn'y say what game you were playing. If its DA or TA you may want to at least eliminat the enemy spy so you get back the function of what ever tile the spy is on. Besides, doing so may make the AI try to get a new py mking it waste money it probably cant afford to lose.

Its easier to go to the Domestic Screen and then Espionage and eliminate them that way. Just double click on the enemy spy for whatever building and POOF, he's gone. Provided of course you have some spies too.

Thanks for the confirmation on that. What about if they surrender to someone else? That happens to me as often as them surrending to me, and far more often than I can eliminate them completely before surrendering.