none Effectiveness of using insect parasites to suppress or eliminate stored-product insect populations may be reduced by capture of up to 100% of parasites in warehouse light traps. In this study, the attractiveness of blacklight traps to Bracon hebetor was compared in rooms with combinations of host-rearing medium and parasite hosts, for varying photoperiods. Presence of host larvae (Cadra cautella) in the rearing medium caused a significant decrease in blacklight trap capture of female parasites, but had no significant effect on capture of males. Presence of host-rearing medium alone and the room's lighting conditions (constant light, no light, or a 12:12, light:dark, photoperiod) had no significant effect on parasite capture. Significantly more B. hebetor adults were caught in blacklight than suction only traps, indicating that true attraction rather than random capture occurred.