They really do not need to be fed. You can feed it occassionally if you want but it's not needed.

I agree with tommyr,
bugs are not neccesary for it's lifecycle but it helps the plant grow.
Since nepenthes are tropical they don't need a dormancy.
Your nepenthes could go it's whole life without catching a single bug.
The only benefits to catching bugs is a little growth spurt.
In winter just don't feed your plant, it doesnt need bugs.
- Adrian

Yellowing leaves can be caused by too much sun, too much or too little water, or by too little nitrogen.

As far as feeding goes, most carnivorous plants can go a long time, some basically forever, without catching anything as Tommyr and Carnivorousplants indicated. Insects do enhance their growth and health, especially with Nepenthes since they tend to be specifically geared towards catching and digesting insects quickly. They have been noted as being capable of digesting insects in less than half the time of other carnivorous plants. Insects are active all the time in the tropics so Nepenthes will catch them all times of the year. You can go without feeding the plant in the winter, but it will not hurt to do so if you want to. I do as I simply do not like to manually fertilize the plant with orchid fertilizers all the time (which is what a lot of people use in leu of insects in winter). You can use any type of insect, spider, or worm; maggots, flies, bloodworms, crickets, fruit flies, moths and so forth are all just fertilizer for the plants. Just make sure the prey is small enough to be submerged in the digestive fluid. If you do manually feed the plant, do so every couple of weeks by adding one small prey item to one healthy pitcher. You will occasionally see a spider, roach, cricket, ant, or stray fly caught in the plant even in winter as those critters often try to overwinter indoors or hatch out inside where you do not notice them.

Mine doesn't get fed in winter. They go outside in the spring. They catch enough during the growing season anyway outdoors.

This is just a shot in the dark, but what about those freeze dried bloodworms used to feed fish. If there aren't additional additives, it might be a cheap and easy way to feed your plants.

I use frozen bloodworms. I like them because they have soft bodies so my neps get way more out of a small amount of bloodworms than they would with crickets. I do notice when I feed them they do get a growth spurt. If you are going to feed your neps, I would bloodworms. Only feed them once or twice a month.

Thanks for the replies everyone, lots of good information there. I don't use any kind of foliar spray so it sounds like the occasional meal would be a good idea. Since the bloodworms seem to work well for others, I think I'll pick some up and give them a try.
-Don

A yellow leaf could also be a very old leaf, whose time is up. And occasional cricket would be fine.

Do Nepenthes suffer negative effects from getting more than one or two bugs per month? I would think that, being tropical as they are, they would naturally get scads of bugs.

Antechron,

No it will not harm the plant to get more than one insect per two weeks. As you surmised, a Nepenthes outdoors in the tropics would catch dozens of insects each week. The thing is, too many insects captured can rot and stink and potentially shorten the life of the pitcher, but will not harm the plant overall. Best bet is just feed the plant every once in a while and let it catch what it will othewise.

no need to feed.they should naturally attract insects, in fact, its bad to OVER FEED. that makes the plant pitchers wither up. believe me. i know.

Some people also apply a few pellets (variable types) of Osmocote.