Cyhalothrin (Clocythrin, Lambda-cyhalothrin, (RS)-α-Cyano-3-phenoxybenzyl-(Z)-(1RS,3RS)-(2-chloro-3,3,3-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylate, CAS#68085-85-8) is an organic compound that is used as a pesticide. It is a pyrethroid, a class of man-made insecticides that mimic the structure and insecticidal properties of the naturally-occurring insecticide pyrethrum which comes from the flowers of chrysanthemums. Synthetic pyrethroids, like lambda-cyhalothrin, are often preferred as an active ingredient in insecticides because they remain effective for longer periods of time. It is a colorless solid, although samples can appear beige, with a mild odor. It has a low water solubility and is nonvolatile. It is used to control insects in cotton crops.

Lambda-cyhalothrin is a mixture of isomers of cyhalothrin. In the USA, 'Triazicide' and 'Hot Shot' are used in the Home Landsape and Garden markets. Home Depot carries a brand of the Lambda-cyhalothrin insecticide under the brand name Real Kill and Spectracide Bug Off. Terro also makes an outdoor ant and other insect prevention treatment similar to Home Defense using this ingredient. Sygenta held the patent for Lambda-cyhalothrin. This patent expired in most major markets in 2003. Lambda cyhalothrin may be marketed as Charge, Excaliber, Grenade, Hallmark, Icon, Karate, Matador, OMS 0321, PP321, Saber, Samurai , and Sentinel. Gamma-cyhalothrin is a single stereoisomer of the pyrethroid insecticide cyhalothrin, and as such shares physical, chemical, and biological properties with both cyhalothrin and lambda-cyhalothrin, which are mixtures of 4 and 2 isomers respectively. Gamma-cyhalothrin is the most insecticidally active isomer of cyhalothrin/lambda-cyhalothrin, and thus the technical gamma-cyhalothrin product may be considered a refined form of cyhalothrin/lambda-cyhalothrin in that it has been purified by removal of less active and inactive isomers. Thus, similar levels of insecticidal efficacy for gamma-cyhalothrin can be obtained with significantly reduced application rates as compared with either cyhalothrin or lambda-cyhalothrin. The tolerance under 40 CFR 180.438 currently identifies lambda-cyhalothrin as a 1:1 mixture of two isomers and their epimers, one of which is the gamma isomer. The gamma isomer is present at 42% in this mixture. By contrast in the proposed tolerance expression the gamma isomer is present at 98% in the mixture. Home Depot carries a brand of the Gamma-cyhalothrin insecticide under the brand name Spectracide Triazacide.

Cyhalothrin has wide-spectrum and quick killing action , higher efficacy and longer duration of effectiveness than Permethrin, stable to light. Especially it has killing action to insect spawns, and ideal for control and prevention of insects which are resistant to organic phosphorous pesticide. Its effectiveness lasts for four weeks in prevention of flies. It is also used in control of livestorle pests, infection pests, flies and storage pests.