All stages of the mite may be found in older bees. The highest number of mites per bee is attained in bees 11-12 days old, and the mite population declines in bees more than 21 days old. Mated female mites leave the breathing tubes where they developed and climb to the tip of a body hair. As bees come in contact with one another, the mites attach themselves to the hairs of a passing bee and enter the tracheae through the thoracic spiracles. If the mite does not locate a new host within 24 hours, it will die.
Mites leave the tracheae after the death of the bee.
Drifting bees between hives and swarms from infested colonies are ways that the mite can be spread within the apiary and between apiaries. Host Susceptibility to the Mite Large variations in susceptibility to infestation among U. S. bee stocks have been found. Worker bees become rapidly less susceptible to infestation as they age, and bees more than 9 days old rarely become infested. Queen honey bees also exhibit a rapid decline in susceptibility to mite infestation with increasing age. Heavy mite infestations are most likely after seasons of poor honey yields and in situations when brood rearing is suppressed during the summer.