Much of my understanding about how to cook and care for the the "little pigs" has been won through trial and error. There just isn't an operating manuel. As you might recall, I started "field dressing" my porcini a couple years ago in an effort to keep them clean and to combat the bugs that are as boletivoracious as us. Boletus rex-veris, in contrast to B. edulis, does much of its growing underground, so it can be quite a dirty mushroom. Dirt and duff-covered mushrooms piled together in a basket or bucket will share their dirt like STDs, making for a difficult cleaning proposition at home, particularly with the pores under the cap. Wherever I happen to find them, I clean them up and check for insect infestations, taking precautions to cover up the scene of the capture when I'm finished.
And don't be fooled. Bolete fly larvae can riddle a mushroom with their hungry tunneling in the time that it takes to drive your haul home from the mountains. As they warm up, the larvae become more active. Unless you crank your air conditioner, the temperature in your car will cause the bugs to stir. This isn't too much of a problem provided you don't dilly-dally along the way—and you get the mushrooms in the refrigerator asap.
I've been paying close attention to a recent batch. A few mushrooms that got field dressed and looked absolutely spotless before the drive home ended up having some noticeable tunneling within three hours of picking. Others that still looked perfect got sliced in half again (i.e. quartered) in my kitchen. This revealed minor bug activity that required immediate action. Finally, even mushrooms that passed with flying colors required checking after a day or two in the fridge, and some of these showed minor infestation. The point is, if you want to pick and eat porcini and not cook up a panful of maggots, you need to be vigilant.
The bolete below has the appearance of a #1 button. It was firm and didn't show any signs of infestation when I trimmed the stem. I decided to keep it whole. After a week in the fridge, this is what it looked like. Look closely and you'll see that the worms attacked via the cap, not the stem. If I had cut the mushroom in half when I picked it, I might have been able to isolate the infestation and save it.
If this is all too much for some folks, who don't even want to think about extra protein in their food...well, mushroom hunting probably isn't your cup of beef.
P.S. If you're in British Columbia, I'd like to know whether you find B. rex-veris, and if so, how far north.