I refuse to believe that there are no bugs to be had in North Carolina. However, you can bug bugs, live or dead, or feed with an appropriate organic dilute fertilizer directly into the pitcher.

You don't have to feed them at all actually. They get enough during the year anyway. Bugs are like desert to them.

Don't worry about it.

It is according to what genus of pitcher plant you have.

Sarracenias, Darlingtonias, Cephalotus, and Heliamphora all can do without insects for long lengths of time with no ill effects. In general, such plants do grow larger and healthier when they do get a shot of nutrients on occasion.

Nepenthes tend to do better when they acquire insects as well, however; to a much greater degree then other carnivorous plants. A Nepenthes that does not get enough insects might stop pitchering, for instance, due to lack of nitrogen.

As stated before by Brendan of Bonsai, you can always rest assured that there will be at least the odd gnat or fruitfly in your house even in winter if we are talking about a Nepenthes. The North American species will not catch anything over winter and should be dormant by now.

You can use foliar feeds in very dilute strength, down to 1/4 to even 1/10 of regular feeding applications, on Nepenthes every month to every two weeks at most, but the best to use would be Orchid blood meal fertilizer from what I have read. I have never fertilized my Nepenthes and really do not worry overmuch about insects for it over winter. I just make sure it gets a good dose in late fall, a couple large insects, just to tide it over for three months. They do not need much nitrogen to grow properly anyways.

Like Tommyr stated, insects would be about like vitamins for carnivorous plants, not necessary in the long run, but helpful in moderation.