In one study, california researchers looked at ways that growers may more efficiently use their sticky cards. Sticky cards were placed 8 to 16 inches above the crop and researchers changed the cards once or twice a week. Western flower thrips, greenhouse whiteflies, leaf miner adults, and winged aphids were caught an the cards. Whitefly catch tended to be uniform, but more aphids and thrips were caught on the bottom half of the cards. There was more variation in trap catch along the length compared to the width of the card.
Growers can then greatly reduce the time spent counting insects and reduce their monitoring costs.
Larger cards tend to catch a greater diversity of insects than smaller cards, and trap catches tend to increase with size. Thrips Light blue cards are more effective in trapping WFT and may be used over thrips-sensitive plants such as roses or African violets. Yellow cards are more effective for general pest monitoring, and adult thrips may be easier to see on a yellow card compared to a blue card. Use a handlens to distinguish adult thrips from grains of peatmoss and other debris. WFT adults are narrow, 0.04 to 0.08 inches long, with 2 pairs of fringed wings that are held parallel over their body.