Deleting Vectors that Point to the Same Objects

Hello, I hope everybody had a good New Year.

I have a class that looks like the following:

class Foo {
public:
        Foo();
        ~Foo() {} // Destructor is defined.
....
private:
        std::vector<Bar*> _list1;
        std::vector<Bar*> _list2;
....
};

As my program runs, _list1 and _list2 are populated as follows:
Bar* bar = new Bar();
_list1.push_back(bar);
_list2.push_back(bar);

In general, _list2 is a subset of _list1, so it isn't redundant.

My question is, what do I need to put in the destructor of Foo to
correctly delete these vectors? When Foo is deleted, I want all the
Bars contained in the two vectors to be deleted as well.

As I understand it, because I didn't initialize the vectors with the
new keyword, they are automatically deleted along with Foo (hence the
empty destructor). However, the destructor for std::vector
automatically calls the destructor of all of its elements. Let's say
_list1 is deleted first, this means _list2 is full of dangling
pointers, and deleting _list2 in the same fashion would be bad.

Thanks for your help,
Michael