Varroa Sensitive Hygiene is a fascinating genetic trait that allows worker bees to detect female mites that are reproducing beneath a capped cell. It's likely the bees detect reproductive mites by smell. The worker bees uncap and remove a large percentage of pupae which were infested with reproductive mites, and throw them outside the hive. The female mite must then find another cell to occupy, and start over. The life cycle of the mite is disrupted by these natural resistance mechanisms as opposed to using chemical miticide applications. It's not that VSH bees have no mites, but they naturally keep the mite population in check and very often well below a treatment threshold. We have been using instrumentally inseminated VSH breeding stock for years to solidify the gene in our breeding population. Our original VSH breeder queens were supplied by Tom Glenn. We have also added Pol Line Hygienic Italians to our stock in addition to VSH. After Tom retired we purchased II'd VSH queens from VP Queens. These traits are the foundation of our mite resistant honeybees. In addition to mite resistance, the VSH bees are highly hygienic and are highly resistant to many brood issues including American Foulbrood.