溴氰菊酯(Deltamethrin)是一种农用杀虫药，中国大陆通称「敌杀死」或保棉丹、克敌等，对害虫的毒效可达DDT的100倍，大量用于棉花种植业，也有稀释版本用于家用。对塑料制品有腐蚀性，不能装于塑料容器。

初产物呈白色斜方针状晶体，熔点101~102℃，沸点300℃。常温下几乎不溶于水，只溶于多种有机溶剂。对翅目系害虫有剧毒性，介壳虫、盲蝽象等也有大规模消灭效果，人体皮肤接触可引起刺激症状，出现红疹，重度中毒者可出现肌束震颤和抽搐致死，误服者饮适量温水催吐，就医用葛根素治疗。

农用者需注意对鱼类和蜜蜂有剧毒，但已经对DDT抗药的昆虫对敌杀死也会抗药。对螨蚧类的防效甚低，并不适用。棉花、茶树系农作物效果佳，茄果类、蔬菜、芦笋、水稻、烟草、小麦、玉米等也可使用，香蕉、李子等效果稍差但也可用。在气温低时效果较好最好于冬天施放，不可与碱性物质混用，以免降低药效，叶菜类收获前15天禁用。

Deltamethrin is a pyrethroid ester insecticide.

Deltamethrin products are among the most popular and widely used insecticides in the world and have become very popular with pest control operators and individuals in the United States. This material is a member of one of the safest classes of pesticides: synthetic pyrethroids. This pesticide is highly toxic to aquatic life, particularly fish, and therefore must be used with extreme caution around water. Although generally considered safe to use around humans, it is still neurotoxic to humans. Deltamethrin is able to pass from a woman's skin through her blood and into her breast milk.