Every new nucleus colony, package, swarm or second-hand hive box can carry pests and diseases invisibly — American and European foulbrood spores, chalkbrood, nosema, tracheal and varroa mites, or wax moth eggs can all hitch a ride on frames, comb and woodware. Good apiary hygiene keeps anything new physically separated from the established hive row until it has been watched and, where needed, treated.
Many national bee inspectorates recommend a minimum of roughly 3 miles (5km) of true isolation for colonies of unknown health status, and treat any second-hand equipment of unknown origin as contaminated until proven otherwise — scorching or irradiating it before it ever touches a live colony.
A new nucleus colony and a pile of second-hand equipment sit on an isolated quarantine stand, separated from the main apiary by a boundary line, while an inspection-progress ring and a drifting-bee count show how distance, time and treatment cut disease-transfer risk.
Contamination risk falls as isolation distance and days under observation increase and as stronger equipment decontamination is applied — but rises sharply if the new colony shows disease symptoms, regardless of the other precautions.
Drag the colony farther from the main hives to reduce drifting-bee crossings, wind the days-in-quarantine slider toward the 21-day brood cycle, pick an equipment treatment, and toggle whether the colony looks healthy or symptomatic to see the risk score respond.
Because worker brood takes about 21 days to emerge, many diseases only become visible on comb after a full brood cycle — which is why inspectors treat anything shorter than three weeks of observation as inconclusive.