flies & yellow jackets

["LindaK" <jazena@kelp.net>]

Does anyone know if yellow jackets, (wasps which are carnivorous) eat fly
larvae?  Year before last I put up all kinds of yellow jacket traps all
around my one acre, and lots of fly traps also, but had lots of both insects
all summer long anyway.
    Last year I put up a couple of fly traps (the kinds with the attractant
in water) but didn't get around to putting up any yellow jacket traps, and I
didn't have near the fly problem as the year before. And while I had lots of
yellow jackets they never bothered me.  (And honestly, I don't know if they
bothered the horses).  I realize there could be many variables to cause this
condition, but was wondering if maybe the fly larvae, or the flies
themselves, were kept in check naturally by the yellow jackets???
    I know this isn't exactly endurance related, but all of us have to deal
with flies.
Thanks for any info.
Lindak
Perris, CA