Magnitude differences between IRAC 1 and W1 plotted against the magnitude differences between IRAC 2 and W2 for the 248 protostars detected in all four bands. Labeled sources, above and to the right of the blue lines, satisfy the outburst thresholds for both wavelengths. The encircled protostar, HOPS 223, satisfies the outburst thresholds at all three wavelengths.