Food theft is a common foraging strategy in birds, and many arthropods steal prey trapped by orb-weaving spiders. Some fireflies (Coleoptera: Lampyridae) within the North American genus Photuris Dejean (Coleoptera: Lampyridae) are specialist predators which actively hunt for and sequester chemical defenses (lucibufagins) from other fireflies. Here we present the first description of kleptoparasitic behavior by female Photuris fireflies, which we have observed stealing wrapped fireflies of the genus Photinus Laporte from spider webs. Photuris females thus appear capable of three distinct foraging strategies: hawking, aggressive flash mimicry, and kleptoparasitism. We discuss some factors that might have favored the evolution of kleptoparasitism by this specialist predator.