After you have harvested honey or determined that you will not be harvesting honey – it is now time (July) to treat your bees for Varroa mites. If you have not yet obtained your treatments you need to order them right away.
For what it is worth I personally plan to use Apiguard at this time of year – because it is hot, and Apivar works better in hot weather while some other treatments become harmful at high temps. But any of these will work if used correctly.
One word of caution – Stinky treatments like Apiguard, and Mite-away-quick-strips produce smelly fumes. Hives need proper amounts of ventilation and must have a strong enough population to fan and ventilate the hives. Not enough ventilation or not enough bees to fan can result in absconding (apiguard) or queen death (Miteaway) – an interuption in brood production or some brood death is not unusual or cause for alarm.