We present 24 \mu m and 70 \mu m MIPS ( Multiband Imaging Photometer for Spitzer ) observations of 70 A through M-type dwarfs with estimated ages from 8 Myr to 1.1 Gyr , as part of a Spitzer guaranteed time program , including a re-analysis of some previously published source photometry .
Our sample is selected from stars with common youth indicators such as lithium abundance , X-ray activity , chromospheric activity , and rapid rotation .
We compare our MIPS observations to empirically derived K _ { s } - [ 24 ] colors as a function of the stellar effective temperature to identify 24 \mu m and 70 \mu m excesses .
We place constraints or upper limits on dust temperatures and fractional infrared luminosities with a simple blackbody dust model .

We confirm the previously published 70 \mu m excesses for HD 92945 , HD 112429 , and AU Mic , and provide updated flux density measurements for these sources .
We present the discovery of 70 \mu m excesses for five stars : HD 7590 , HD 10008 , HD 59967 , HD 73350 , and HD 135599 .
HD 135599 is also a known Spitzer IRS ( Infra-Red Spectrograph ) excess source , and we confirm the excess at 24 \mu m. We also present the detection of 24 \mu m excesses for ten stars : HD 10008 , GJ 3400A , HD 73350 , HD 112429 , HD 123998 , HD 175742 , AT Mic , BO Mic , HD 358623 and Gl 907.1 .
We find that large 70 \mu m excesses are less common around stars with effective temperatures of less than 5000 K ( 3.7 ^ { +7.6 } _ { -1.1 } % ) than around stars with effective temperatures between 5000 K and 6000 K ( 21.4 ^ { +9.5 } _ { -5.7 } % ) , despite the cooler stars having a younger median age in our sample ( 12 Myr vs. 340 Myr ) .
We find that the previously reported excess for TWA 13A at 70 \mu m is due to a nearby background galaxy , and the previously reported excess for HD 177724 is due to saturation of the near-infrared photometry used to predict the mid-infrared stellar flux contribution .

In the Appendix , we present an updated analysis of dust grain removal time-scales due to grain-grain collisions and radiation pressure , Poynting-Robertson drag , stellar wind drag and planet-dust dynamical interaction .
We find that drag forces can be important for disk dynamics relative to grain-grain collisions for L _ { IR } /L _ { * } < 10 ^ { -4 } , and that stellar wind drag is more important than P-R drag for K and M dwarfs , and possibly for young ( < 1 Gyr ) G dwarfs as well .