  White dwarf WD 1145+017 is orbited by several clouds of dust, possibly
emanating from actively disintegrating bodies. These dust clouds reveal
themselves through deep, broad, and evolving transits in the star's light
curve. Here, we report two epochs of multi-wavelength photometric observations
of WD 1145+017, including several filters in the optical, K$_\mathrm{s}$ and
4.5 $\mu$m bands in 2016 and 2017. The observed transit depths are different at
these wavelengths. However, after correcting for excess dust emission at
K$_\mathrm{s}$ and 4.5 $\mu$m, we find the transit depths for the white dwarf
itself are the same at all wavelengths, at least to within the observational
uncertainties of $\sim$5%-10%. From this surprising result, and under the
assumption of low optical depth dust clouds, we conclude that there is a
deficit of small particles (with radii $s \lesssim$ 1.5 $\mu$m) in the
transiting material. We propose a model wherein only large particles can
survive the high equilibrium temperature environment corresponding to 4.5 hr
orbital periods around WD 1145+017, while small particles sublimate rapidly. In
addition, we evaluate dust models that are permitted by our measurements of
infrared emission.
