  We describe a search for infra-red excess emission from dusty circumstellar
material around 180,000 stars observed by the Kepler and WISE missions. This
study is motivated by i) the potential to find bright warm disks around planet
host stars, ii) a need to characterise the distribution of rare warm disks, and
iii) the possible identification of candidates for discovering transiting dust
concentrations. We find about 8,000 stars that have excess emission, mostly at
12um. The positions of these stars correlate with the 100um background level so
most of the flux measurements associated with these excesses are spurious. We
identify 271 stars with plausible excesses by making a 5MJy/sr cut in the IRAS
100um emission. The number counts of these excesses, at both 12 and 22um, have
the same distribution as extra-Galactic number counts. Thus, although some
excesses may be circumstellar, most can be explained as chance alignments with
background galaxies. The one exception is a 22um excess associated with a
relatively nearby A-type star that we were able to confirm because the disk
occurrence rate is independent of stellar distance. Despite our low detection
rate, these results place valuable upper limits on the distribution of large
mid-infrared excesses; e.g. fewer than 1:1000 stars have 12um excesses (F_
obs/F_star) larger than a factor of five. In contrast to previous studies, we
find no evidence for disks around 1790 stars with candidate planets (we
attribute one significant 12um excess to a background galaxy), and no evidence
that the disk distribution around planet hosts is different to the bulk
population. Higher resolution imaging of stars with excesses is the best way to
rule out galaxy confusion and identify more reliable disk candidates among
Kepler stars. A similar survey to ours that focusses on nearby stars would be
well suited to finding the distribution of rare warm disks.
