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Determining the Galactic distribution and numbers of massive stars, such asWolf-Rayet stars (WRs), is hampered by intervening Galactic or localcircumstellar dust obscuration. In order to probe such regions of the Galaxy wecan use infrared observations, which provide a means for finding such hiddenpopulations through the dust. The availability of both 2MASS andSpitzer/GLIMPSE large-scale survey data provides infrared colours from 1.25 to8$\mu$m for a large fraction of the inner Galactic plane. In 2005 we initiateda pilot study of the combined set of infrared colours for two GLIMPSE fieldsand showed that WRs typically occupy a sparsely populated region of the colourspace. We followed up 42 of our WR candidates spectroscopically in thenear-infrared, and with limited additional observations of some of thesecandidates in the optical. Six new WRs, four late-type WN and two late-type WCstars, were discovered as a result. Of the remaining $\sim$86% of the sample,five appear to be O-type stars. 21 stars are likely of type Be, and 10 starsappear to be of late-type, or possibly young stellar objects, which have"contaminated" the infrared color space. The survey is generally unbiasedtowards clusters or field stars, and the new WRs found are in both the fieldand in and around the RCW 49 region (including cluster Westerlund 2). In thiswork, and in our other recent work, we show that the infrared broad-bandcolours to be the most efficient means of identifying (particularly,dust-obscured) candidate massive stars, notably WRs.

Galactic Evolved Massive Stars Discovered by Their Infrared Emission