We have spoken with the manufacturer and they have stated the Dynatrap Indoor / Outdoor Insect Twist to Close Trap (DT1050) can be used during the day and should work for yellow jackets and most flies that are attrached to the Co2 that it emits.
Flying insects around the Dynatrap Indoor/Outdoor (DT1050) are attracted to the unit by UV light and CO2 that is generated by the photo-catalysis between the UV lamps and special TiO2 coating. The fan then pulls the insects into the screened base, trapping them until they dehydrate and die.