Yes, to date, the Governor has not authorized arrest powers. They are to work with the Border Patrol, not independent teams.
http://governor.state.tx.us/news/press-release/20025/
“Texas put out the call and you have answered. Your mission is clear - to be a visible presence to deter criminal activity - and contribute additional eyes and ears to assist law enforcement and Border Patrol agents along the border,” Gov. Perry said. “At stake are the lives of innocent people along both sides of the border, and the safety and well-being of communities across the state, and our nation, placed in jeopardy by the criminal activities of transnational gangs and drug cartels.”
You don't understand … it's not an issue to be solved with police power, it is an issue to be solved with the power of the sword.
The lowball estimates of how many illegal aliens are present in the US are 7 million, the higher are 20 million and I've heard one at 35 million.
The Total US population is approximately 314 million. So this yields the following:
If it's the first one it's quite worrisome, if it's one of the other two then an invasion.7/314 ≈ 2.2% 20/314 ≈ 6.4% 35/314 ≈ 11.1%