I recommend and use Eaton-Dikeman 915. Insects washed out onto the filter paper can then be examined under a scope. Alternatively, one can wash the trays out onto white paper towels with a detergent solution, then examine under a stereoscope for insects. Again, I have found that wheat germ is an easier food lure to use and is more attractive to the larvae. I advise against using the oil attractants.
Adults are much more mobile than larvae.
Also, the adults are easier to catch if present. Pay special attention to trapped larvae. The trapping of one larvae has about 50-100 times the significance of trapping a single adult. For Trogoderma in general, if one larvae is trapped, be alarmed. If two or more are trapped, or if one location produces consecutive larval catches, this indicates a potential major problem.