  The incidence of dusty debris disks around low- and intermediate-mass stars
has been investigated numerous times in order to understand the early stages of
planet formation. Most notably, the IRAS mission observed the entire sky at
mid- and far-IR wavelengths, identifying the first debris disk systems, but was
unable to detect a statistically significant sample of warm debris disks due to
its limited sensitivity at 12 microns. Using Tycho-2 Spectral Catalog stars
previously shown to exhibit 8 micron mid-infrared circumstellar excesses
confirmed at 24 microns in the Spitzer GLIMPSE survey, we investigate the
frequency of mid-IR excesses among intermediate-mass (2--4 solar mass) stars in
a complete volume-limited sample. Our study of 338 stars is four times larger
than a complete sample of 12 micron sources from the IRAS Point Source Catalog.
We find that 0.3+-0.3% of intermediate-mass stars exhibit a signature of a
possible terrestrial-temperature debris disks at wavelengths of 8 microns and
greater. We also find that 1.2+-0.6% of intermediate-mass stars exhibit
evidence for circumstellar disks undergoing inner disk clearing, i.e.,
candidate transition disk systems. Using stellar lifetimes and the frequency of
transition and primordial disks within a given spectral type, we find that
pre-main-sequence disks around intermediate-mass stars dissipate in 5+-2 Myr,
consistent with other studies.
