Abstract: A bottletop plug device for trapping flying insects. The bottletop plug device is a reversibly attachable accessory that converts a consumer-supplied narrow-neck bottle into a trap for flying insects. The plug device has a generally tapered body that includes a lower body segment and bottom tip insertable into a baited bottle, a middle body segment having a stack of resilient protruding circumferential ribs sealable against an inside wall of a bottle neck, and an upper body segment having a wide mouth entrance to an internal passageway or chamber that runs down the length of the body and through the bottom tip. At the bottom of the channel, a narrow “insect sized” orifice allows insects to have essentially one-way ingress into the bottle.