We work with breeders who produce VSH (varroa sensitive hygiene) queens who are hybrids of Carniolan/Italian. The breeder queens originally came from Glenn Apiaries who worked with USDA scientists in developing Varroa Sensitive Hygiene, a naturally occurring trait in honey bees that causes the worker bees to detect, uncap and remove varroa mite infested brood. Our queens are the successful daughters of these breeder queens who are sensitized to our Colorado environment. Varroa sensitivity does not mean hives will be immune to varroa!! You must test your hives several times a year for varroa counts!