Repellers

A repeller is a device or substance designed to deter unwanted animals or pests by emitting a deterrent stimulus or by creating an inhospitable environment. They are used in households, agriculture, and public health to reduce damage or nuisance without killing pests.

Chemical repellents work by applying volatile or contact-active compounds that pests find aversive or odorous. Examples include insect repellents for humans (DEET, picaridin, IR3535), plant-based repellents such as citronella, and treated fabrics. In agriculture, crop repellents may be used on seeds or plants to deter insects; some are based on bitter-tasting compounds or odors.

Physical and visual repellents include barriers (nets, fencing) and deterrent devices such as reflective tapes, decoy predators, motion-activated lights, sprinklers, and noise- or light-emitting devices. These work by creating an environment pests find unsafe or confusing.

Ultrasonic and electrical repellents claim to deter rodents, insects, or other animals by high-frequency sound or electric fields. Scientific evidence for sustained efficacy is mixed; effects may be temporary, context-dependent, and can affect non-target species.

Pheromone-based and biological repellents use chemical signals to disrupt mating or behavior or introduce competing odors. These tools are often used as components of integrated pest management.

Limitations: repellents typically provide temporary relief, and effectiveness varies by species and environment; proper use, timing, and combination with other strategies improve results. Safety and environmental considerations also apply.