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Yellow and blue sticky traps

Yellow and blue sticky traps are coloured-glue cards or sheets used in integrated pest management for monitoring and mass trapping of flying insect pests. The colour spectrum of each trap selectively attracts different pest groups, allowing growers to track population dynamics in real time and to physically remove a fraction of the adult flying population.

Principle

Flying insects respond to specific wavelengths of reflected light when seeking host plants or flowers. Bright yellow approximates the spectral signature of fresh foliage and attracts whitefly, aphids, leafhoppers, fungus gnats and some thrips. Bright blue is closer to the spectrum reflected by certain flowers and is highly selective for flower thrips (Frankliniella and Thrips genera). Adhesive on the trap surface immobilises insects on contact. Counts over time index population pressure and complement plant inspection.

Implementation

UC IPM recommends deploying sticky traps just above the crop canopy in both greenhouse and open-field settings. Indian extension recommends approximately 20-25 sheets per acre for monitoring deployments. Traps are inspected weekly with adhered insects identified and counted; sheets are replaced when full or when adhesive degrades. Mass-trapping deployments use higher densities. Traps serve as both a monitoring tool — to time interventions against economic threshold levels — and a physical removal mechanism.

Adoption context

Yellow sticky traps are widely used in vegetable, cotton, chilli and floriculture IPM packages disseminated by ICAR-NCIPM, state agriculture departments and KVKs. Blue traps are concentrated in protected-cultivation polyhouses growing thrips-sensitive crops (capsicum, rose, gerbera) and in open-field chilli for Thrips parvispinus monitoring.

Limitations

The traps capture non-target beneficial insects (pollinators, parasitoids and predators) alongside pests, partially offsetting their pest-management value. Adhesive degrades in heat, rain and dust, reducing effectiveness within days in some agro-climates. Trap counts must be interpreted with awareness of weather and crop stage; raw catch numbers are not directly comparable to economic threshold levels without local calibration.

See also Pheromone Traps, Solar Light Traps, Ipm Vegetables and Ipm Chilli Spray Schedule.

References

  1. Monitoring with Sticky Traps. UC Statewide IPM Program.
  2. Sticky Trap Monitoring of Insect Pests. UC Agriculture and Natural Resources.