Odd question: I'm in charge of sealing all the little cracks and such in our new construction before we insulate and put up drywall. I've been using spray foam for the most part. My question is, do you worry about the seams where the OSB on the walls meet. We're talking about 1/4" little slits where you can see light. I know there is siding on the outside, then insulation and drywall. I just don't want flies sneaking in (we have flies in our current house, and they drive me nuts!) Foam just doesn't seem practical for these seams. I've contemplated caulking or even just running a strip of duct tape over the area of seam.

Suggestions? What do professionals do?

You want to seal anything that air can move through.

And don't forget the holes in the top plates where wires or pipes go through.

For a whole house I would get a foam gun and separate foam. Much better control and lower cost in volumne.

There are many different brands and sources. Here is one.

http://www.energyfederation.org/consumer/default.php/cPath/21_28_1268

Great Stuff also comes in that formation, call Great Stuff Pro.

Duct tape has a short life. The adhesive dries out and it falls off. Should not be used on ducts either. Or anything else that is not temporary.

EFI also distributes a number of sealing products.

http://www.energyfederation.org/consumer/default.php/cPath/21

you should be using some sort of housewrap on the outside of the osb. Once the housewrap is on you can tape the seams of the housewrap with the approved tape.