How often should I feed my Venus flytrap?

This depends upon the plant. You can put a bug in any trap leaf that is open. Once a trap captures a bug, it requires about a week to digest it. Then it will reopen and be ready for a new bug. This means that if you have a large plant with about seven traps, on the average one trap will reopen per day, ready for a feeding. This is a lot of work.

On the other hand, you do not have to feed a trap right away just because it opens. Traps can go for weeks without being fed. I have grown plants for more than a year at a time without feeding them. They grow fine, just more slowly.

I usually feed my plants about four times each year. Each plant gets about three bugs per feeding. Twelve bugs per plant doesn't seem like much, but I have about 30 plants in my terraria, so that comes to about 360 bugs. That's a lot of time spent chanting Poe in my living room, when I could be off teasing my neighbor's cat.

Source: http://www.sarracenia.com/faq.html